,transcriber's ,notes ,texts printed in italics and bold face in the source document have been transcribed between underscores and equal signs respectively4 ,small capitals have been transcribed as ,,all ,,capitals4 ,more ,transcriber's ,notes may be found at the end of this text4 ,vacuum ,cleaning ,systems ,a ,treatise on the ,principles and ,practice of ,mechanical ,cleaning ,,by ,m4 ,s4 ,,cooley1 ,m4 ,e4 ,,mechanical ,,engineer ,,in ,,office ,,of ,,the ,,supervising ,,architect1 ,,treasury ,,department1 ,,washington1 ,d4 ,c4 ,,first ,,edition ,new ,york3 ,,heating ,,and ,,ventilating ,,magazine ,,company1 #aabc ,broadway ,copyright1 #aiac1 ,,by ,,heating ,,and ,,ventilating ,,magazine ,,co4 ,,contents4 ,,chapter ,i4 ,,history ,,of ,,mechanical ,,cleaning4 ,,page ,early ,attempts #c ,limitations of the ,carpet ,sweeper #d ,compressed ,air ,cleaners #e ,vacuum ,produced by ,compressed ,air #g ,compressed ,air ,supplemented by ,vacuum #g ,piston ,pump the ,first ,satisfactory ,vacuum ,producer #i ,systems ,using ,vacuum ,only #aa ,renovator with ,inrush ,slot #ac ,steam ,aspirators ,used as ,vacuum ,producers #ad ,piston ,pump ,used ,without ,separators #ae ,first ,portable ,vacuum ,cleaner #ae ,first ,use of ,stationary ,multi-,stage ,turbine ,blowers #af ,separators ,emptying to ,sewer by ,air ,pressure #ah ,machines ,using ,root ,blowers as ,vacuum ,producers #ah ,,chapter ,,ii4 ,,requirements ,,of ,,an ,,ideal ,,vacuum ,,cleaning ,,system4 ,necessity and ,proper ,location of ,stationary ,parts #bd ,,chapter ,,iii4 ,,the ,,carpet ,,renovator4 ,four ,important ,parts of ,vacuum ,cleaning ,system #be ,the ,straight ,vacuum ,tool #bf ,renovator with ,auxiliary ,slot ,open to ,atmosphere #bg ,renovator with ,two ,cleaning ,slots #cj ,renovator with ,inrush ,slots on ,each ,side #cj ,tests on ,dirty ,carpets #cj ,type ,a ,renovator ,most ,efficient on ,dirty ,carpets #cf ,tests of ,carpets 8,artificially0 ,soiled #cf ,effort ,necessary to ,operate ,various ,type of ,renovators #ea ,relative ,damage to ,carpets with ,various ,type of ,renovators #eb ,,chapter ,,iv4 ,,other ,,renovators4 ,different ,form of ,renovator ,necessary to ,clean ,walls1 ,ceilings and ,similar ,flat ,surfaces #fj ,upholstery ,renovators ,disastrous to ,surfaces ,cleaned #fd ,attempts to ,overcome ,destructive ,tendency of ,straight-,slot ,upholstery ,renovator #fd ,upholstery ,renovators ,most ,serviceable ,clothing ,cleaners #fe ,special ,renovators for ,cleaning ,stairs #ff ,renovation of ,furs #ff ,renovation of ,pillows #ff ,,chapter ,v4 ,,stems ,,and ,,handles4 ,use of ,drawn ,steel ,tubing for ,stems of ,cleaning ,tools #gj ,drawn ,aluminum ,tubing for ,long ,stems #ga ,swivel ,joints ,between ,renovator and ,stem #gb ,wear on ,hose ,near ,stem #gd ,methods of ,overcoming ,wear of ,hose #gd ,valves to ,cut ,off ,suction #gh ,,chapter ,,vi4 ,,hose4 ,early ,types ,made of ,canvas-,wound ,rubber ,tubing #hj ,standard ,weight ,adopted #hj ,first ,type ,produced ,especially for ,use in ,vacuum ,cleaning ,work #ha ,first ,attempt to ,produce ,light-,weight ,hose #ha ,other ,types #hb ,hose ,couplings #hb ,hose ,friction #hd ,effect of ,hose ,friction #hh ,most ,economical ,hose ,size for ,carpet and ,floor ,renovators #ic ,conditions for ,plant of ,small ,power #ig ,limit of ,length for ,hose #ii ,,chapter ,,vii4 ,,pipe ,,and ,,fittings4 ,hose ,inlets #ajj ,pipe ,friction #ajg ,determination of ,proper ,size ,pipe #ajg ,determination of ,number of ,sweepers to be ,operated #aac ,determination of ,number of ,risers to be ,installed #aae ,size of ,risers #aae ,illustration of ,effect of ,long ,lines of ,piping #abj ,,chapter ,,viii4 ,,separators4 ,classification of ,separators #abg ,primary ,separators #abg ,secondary ,separators #acj ,complete ,separators #acd ,total ,wet ,separator #ach ,,chapter ,,ix4 ,,vacuum ,,producers4 ,types of ,vacuum ,producers #adb ,displacement ,type #adb ,centrifugal ,type #adb ,power ,required to ,produce ,vacuum #adb ,reciprocating ,pumps #adc ,rotary ,pumps #adh ,centrifugal ,exhausters #aef ,steam ,aspirators #afb ,,chapter ,x4 ,,control4 ,first ,type of ,controller #aff ,second ,form of ,control #afh ,appliances for ,varying ,speed of ,motor-,driven ,vacuum ,pump #aga ,,chapter ,,xi4 ,,scrubbing ,,systems4 ,first ,real ,mechanical ,scrubbing ,device #agf ,combining ,scrubbing with ,dry ,cleaning #agg ,ideal ,separator for ,use with a ,combined ,cleaning and ,scrubbing ,system #agh ,,chapter ,,xii4 ,,selection ,,of ,,cleaning ,,plant4 ,renovators #agi ,hose #ahb ,pipe ,lines #ahb ,separators #ahb ,vacuum ,producers #ahc ,control #ahc ,selection of ,appliances for ,four ,classes of ,work #ahd ,,class #a4--,plant for ,residence or ,small ,office or ,departmental ,building1 to be ,not ,more than ,one-,sweeper ,capacity4 ,,class #b4--,large ,office or ,departmental ,building ,where ,carpet ,cleaning is ,important and ,pipe ,lines are of ,reasonable ,length4 ,,class #c4--,large ,building or ,group of ,buildings ,where ,carpet ,cleaning is ,important and ,long ,lines of ,piping are ,necessary4 ,,class #d4--,large or ,small ,plant ,where ,carpet ,cleaning is ,not an ,important ,function of the ,cleaning ,system4 ,,chapter ,,xiii4 ,,tests4 ,early ,methods of ,testing #ahg ,most ,rational ,system of ,testing #ahi ,use of ,vacometer #aij ,proper ,orifice to be ,used with ,each ,class of ,plant #aia ,,chapter ,,xiv4 ,,specifications4 ,award of ,contracts on ,evaluation ,basis #aic ,determination ,basis of ,evaluation #aic ,specification for ,class #a1 ,plant for ,residence or ,small ,office ,building of ,one-,sweeper ,capacity #aid ,specification for ,class #b1 ,plant for ,large ,office ,building ,having ,pipe ,lines of ,moderate ,length #bjd ,specification for ,class #c1 ,large ,installation1 with ,unusually ,long ,pipe ,lines #bji ,specification for ,class #d1 ,large or ,small ,plant ,where ,carpet ,cleaning is of ,secondary ,importance #bae ,specification for ,class #e1 ,to ,give ,widest ,competition #bah ,,chapter ,,xv4 ,,portable ,,vacuum ,,cleaners4 ,power ,required #bbh ,weight of ,efficient ,portable ,cleaners #bbh ,limit of ,power ,consumption ,when ,attached to ,lighting ,system #bbi ,disadvantage of ,having ,dust ,bag at ,outlet of ,fan #bcj ,portables ,equipped with ,mechanically-,operated ,brushes #bca ,portables ,exhausting ,air ,inside of ,building #bca ,,tables4 ,,page #a4 ,cleaning ,tests of ,dirty ,carpets #cd #b4 ,cleaning ,tests of ,carpets ,filled with ,quicksand #ch #c4 ,cleaning ,tests ,using #a oz4 of ,sand per ,square ,yard of ,carpet #dj #d4 ,comparison of ,tests ,made by ,mr4 ,reeve and by the ,author #dh #e4 ,effort ,necessary to ,operate ,cleaning ,tools #ea #f4 ,vacuum ,required at ,hose ,cock to ,operate ,type ,a ,renovators ,attached to ,varying ,lengths of ,different-,sized ,hose #hi #g4 ,air ,quantities and ,vacuum at ,renovator with #a-;in4 ,hose and #aj in4 ,vacuum at ,hose ,cock #ij #h4 ,air ,quantities and ,vacuum at ,renovator with #a-;in4 ,hose and #f in4 ,vacuum at ,hose ,cock #ij #i4 ,vacuum ,required at ,hose ,cock to ,operate ,type ,c ,renovators with ,various ,lengths of ,three ,sizes of ,hose #ia #aj4 ,air ,quantities ,through ,floor ,brush with ,various ,sizes and ,lengths of ,hose1 ,operated on ,same ,system with ,type ,a ,renovators #ib #aa4 ,horse ,power ,required at ,hose ,cock to ,operate ,bare ,floor ,brushes on ,same ,system with ,type ,a ,renovators #ic #ab4 ,free ,air ,passing ,brush ,type of ,bare ,floor ,renovator ,operated on ,same ,system with ,type ,c ,carpet ,renovators #id #ac4 ,horse ,power at ,hose ,cock with ,brush ,type of ,bare ,floor ,renovator ,operated on ,same ,system with ,type ,c ,carpet ,renovators #id #ad4 ,cubic ,feet of ,free ,air ,passing the ,felt-,covered ,floor ,renovator ,operated on ,same ,system with ,type ,a ,renovators #if #ae4 ,horse ,power ,required at ,hose ,cock to ,operate ,felt-,covered ,floor ,renovators ,operated on ,same ,system with ,type ,a ,renovators #if #af4 ,vacuum at ,hose ,cock with #b in4 ,vacuum at ,type ,a ,renovator #ig #ag4 ,air ,quantities when ,bristle ,bare ,floor ,renovators are ,used in ,conjunction with ,type ,a ,carpet ,renovators at #b in4 ,mercury #ih #ah4 ,pipe ,sizes ,required1 as ,determined by ,air ,passing ,renovators #aji #ai4 ,friction ,loss in ,pipe ,lines1 with ,carpet ,renovators in ,use ,exclusively #aji #bj4 ,pressure ,losses from ,inlet to ,separator in ,system for ,cleaning ,railroad ,cars #aba ,,illustrations4 ,,fig4 ,,page4 #a4 ,early ,type of ,mechanical ,cleaning ,nozzle ,using ,compressed ,air #f #b4 ,another ,type of ,compressed ,air ,cleaning ,nozzle1 ,supplemented with ,vacuum ,pipe #h #c4 ,separators ,used ,with ,combined ,compressed ,air and ,vacuum ,machines #i #d4 ,piston ,type of ,vacuum ,pump1 ,mounted ,tandem ,with ,air ,compressor #i #e4 ,mr4 ,kenney's ,first ,renovators ,vacuum ,alone ,being ,used as ,cleaning ,agent #aj #f4 ,air ,compressors ,arranged for ,operation as ,vacuum ,pumps #aa #g4 ,separators ,installed by ,mr4 ,kenney in ,frick ,building #ab #h4 ,vacuum ,renovator ,with ,inrush ,slot1 ,introduced by the ,sanitary ,devices ,manufacturing ,company #ac #i4 ,first ,portable ,vacuum ,cleaner1 ,constructed by ,dr4 ,william ,noe1 of ,san ,francisco1 in #aije #af #aj4 ,late ,type of ,spencer ,vacuum ,cleaning ,machine1 ,operated by ,multi-,stage ,turbine ,blowers #ag #aa4 ,type ,a1 the ,straight ,vacuum ,tool #bf #ab4 ,type ,b1 with ,wide ,slot and ,wide ,bearing ,surface #bf #ac4 ,type ,c1 with ,auxiliary ,slot1 ,open to ,atmosphere #bh #ad4 ,type ,d1 with ,two ,cleaning ,slots #bh #ae4 ,type ,e1 with ,inrush ,slot on ,each ,side of ,vacuum ,slot #ca #af4 ,type ,f1 an ,exaggerated ,form of ,type ,b #ca #ag4 ,tests of ,three ,renovators on ,dirty ,carpets #ce #ah4 ,cleaning ,tests of ,carpets ,filled with ,quicksand #ci #ai4 ,cleaning ,tests ,using #a oz4 of ,sand ,per ,square ,yard of ,carpet #da #bj4 ,three ,series of ,tests with ,kenney ,type ,a ,renovators #de #ba4 ,tests by ,mr4 ,reeve1 ,using ,type ,c ,renovator #df #bb4 ,tests by ,mr4 ,reeve1 ,using ,type ,d ,renovator #dg #bc4 ,tests ,showing ,efficiency of ,different ,types of ,renovators at ,different ,degrees of ,vacuum #ej #bd4 ,early ,type of ,bare ,floor ,renovator #ee #be4 ,later ,type of ,bare ,floor ,renovator #ee #bf4 ,another ,type of ,bare ,floor ,renovator #ef #bg4 ,bare ,floor ,renovator with ,felt ,cleaning ,surface #eg #bh4 ,bare ,floor ,renovator with ,unusual ,form of ,slot #eh #bi4 ,bare ,floor ,renovator with ,hard ,felt or ,composition ,rubber ,strips #eh #cj4 ,bare ,floor ,renovator with ,rounded ,wearing ,surface #ei #cj;a4 ,the ,tuec ,school ,tool #fb #ca4 ,round ,bristle ,brush for ,carved or ,other ,relief ,work #fb #cb4 ,rubber-,tipped ,corner ,cleaner for ,use on ,carved or ,other ,relief ,work #fb #cc4 ,early ,type of ,upholstery ,renovator #fc #cd4 ,upholstery ,renovator with ,narrow ,slots to ,prevent ,damage to ,furniture #fd #ce4 ,another ,type of ,upholstery ,renovator with ,short ,slots #fe #cf4 ,hand ,brush ,type of ,renovator #fe #cg4 ,form of ,swivel ,joint ,connecting ,stem to ,renovator #gb #ch4 ,swivel ,joint ,arranged to ,prevent ,dust ,lodging ,between the ,wearing ,surfaces #gc #ci4 ,swivel ,joint in ,use #gd #dj4 ,another ,use of ,swivel ,joint1 ,showing ,possibilities of this ,form #ge #da4 ,operator ,cleaning ,trim of ,door with ,swivel ,joint #gf #db4 ,swivel ,joint1 with ,screwed ,union #gf #dc4 ,swivel ,joint ,having ,ball ,bearings #gf #dd4 ,action of ,ball-,bearing ,swivel ,joint #gg #de4 ,illustration of ,defects of ,plug ,cocks #gh #df4 ,bayonet ,type of ,hose ,coupling1 ,introduced by the ,american ,air ,cleaning ,company #hb #dg4 ,all ,rubber ,hose ,coupling ,used by the ,spencer ,turbine ,cleaner ,company #hc #dh4 ,chart for ,determining ,hose ,friction #hf #di4 ,effect of ,increase of ,velocity on the ,friction ,loss #hh #ej4 ,another ,test ,showing ,friction ,loss ,due to ,velocity #hi #ea4 ,inlet ,cock to ,prevent ,air ,leakage when ,not in ,use #aja #eb4 ,type of ,automatic ,self-,closing ,inlet ,cock #ajb #ec4 8,smooth ,bore0 ,pipe ,coupling #ajc #ed4 ,joint ,made of ,standard ,pipe ,flanges #ajd #ee4 ,standard ,durham ,recessed ,drainage ,fittings ,generally ,used in ,vacuum ,cleaning ,installations #aje #ef4 ,friction ,loss in ,pipe ,lines #ajf #eg-fj4 ,diagrams ,showing ,operation of ,brush and ,carpet ,renovators ,under ,different ,conditions #aaj #fa4 ,typical ,floor ,plan of ,office ,building ,illustrating ,number of ,sweepers ,required #aad #fb4 ,plan of ,layout for ,office ,building ,showing ,best ,location 7at d7 for ,vacuum ,producer #aah #fc4 ,vacuum ,cleaning ,layout for a ,passenger ,car ,storage ,yard #abb #fd4 ,arrangement of ,piping ,recommended as ,best for ,passenger ,car ,storage ,yard #abc #fe4 ,good ,location for ,dust ,separator ,where ,large ,areas ,are ,served by ,one ,cleaning ,system #abe #ff4 ,location of ,separators at ,centers of ,groups of ,risers for ,large ,systems #abf #fg4 ,early ,type of ,primary ,separator1 ,used by ,vacuum ,cleaner ,company #abh #fh4 ,primary ,separator ,used by the ,sanitary ,devices ,manufacturing ,company #abh #fi4 ,primary ,separator ,used by the ,general ,compressed ,air and ,vacuum ,cleaning ,company #abi #gj4 ,primary ,separator ,made by the ,blaisdell ,engineering ,co4 #abi #ga4 ,secondary ,separator ,used by the ,vacuum ,cleaner ,company #aca #gb4 ,secondary ,separator ,used by the ,general ,compressed ,air and ,vacuum ,cleaning ,company #aca #gc4 ,secondary ,separator ,used by the ,sanitary ,devices ,manufacturing ,company #acb #gd4 ,type of ,dry ,separator ,used as ,secondary ,separator #acd #ge4 ,form of ,complete ,separator ,used by the ,vacuum ,cleaner ,company #ace #gf4 ,complete ,separator ,brought ,out by the ,electric ,renovator ,manufacturing ,company #acf #gg4 ,complete ,separator ,made by the ,american ,radiator ,company #acg #gg;a4 ,interior ,construction of ,dunn ,vacuum ,cleaning ,machine #adj #gh4 ,power ,consumption and ,efficiency of ,air ,compressor ,used as a ,vacuum ,pump #adc #gi4 ,modification of ,reciprocating ,pump ,made by the ,sanitary ,devices ,manufacturing ,company #add #hj4 ,power ,consumption and ,efficiency of ,modified ,reciprocating ,pump #ade #ha and #hb4 ,indicator ,cards for ,clayton and ,modified ,pumps #adf #hc4 ,one of the ,pumps ,installed in ,connection with the ,vacuum ,cleaning ,system in the ,new ,york ,post ,office1 the ,largest ,reciprocating ,pump ,used for this ,purpose up to the ,present #adh #hd4 ,interior ,arrangement of the ,garden ,city ,rotary ,pump #adi #he4 ,power ,required to ,operate ,garden ,city ,type of ,rotary ,pump #aej #hf4 ,arrangement of ,double-,impeller ,root ,type ,rotary ,pump for ,vacuum ,cleaning ,work #aea #hg4 ,rotary ,pump ,arranged with ,double-,throw ,switch for ,reversing ,pump #aeb #hh4 ,power ,consumption and ,efficiency of ,root ,type of ,pump #aec #hi4 ,the ,rotrex ,vacuum ,pump1 ,used by the ,vacuum ,engineering ,company #aec #ij4 ,late ,type of ,centrifugal ,exhauster ,made by the ,spencer ,turbine ,cleaner ,company #aed #ia4 ,power and ,efficiency ,curves for the ,spencer ,machine #aee #ib4 ,interior ,arrangement of ,invincible ,machine1 ,manufactured by the ,electric ,renovator ,manufacturing ,company #aef #ic4 ,power ,consumption1 ,vacuum and ,efficiency of ,first ,types of ,invincible ,machine #aeg #id4 ,power ,consumption1 ,vacuum and ,efficiency of ,invincible ,machine ,after ,valve ,was ,fitted to ,discharge #aeh #ie4 ,four-,sweeper ,invincible ,plant ,installed in the ,united ,states ,post ,office at ,los ,angeles1 ,cal4 #aei #if4 ,centrifugal ,pump with ,single ,impeller1 ,manufactured by ,the ,united ,electric ,company #afa #if;a4 ,test of ,centrifugal ,pump with ,single ,impeller #afb #ig4 ,steam ,aspirator ,used by the ,american ,air ,cleaning ,company #afc #ih4 ,steam ,consumption of ,steam ,aspirator #afd #ii4 ,first ,type of ,controller ,introduced by the ,sanitary ,devices ,manufacturing ,company1 known as the 8,unloading ,valve0 #afg #ajj4 ,test of ,controller ,connected to ,suction of #h-,sweeper ,piston ,pump #afh #aja4 ,type of ,controller for ,use on ,pumps ,without ,valves #afi #ajb4 ,regulator for ,motor-,driven ,vacuum ,pump1 ,manufactured by the ,cutler-,hammer ,manufacturing ,company #agj #ajc4 ,inspirator ,type ,vacuum ,contactor1 ,used to ,control ,pilot ,motor of ,cutler-,hammer ,controller #aga #ajd4 ,vacometer for ,use in ,testing ,vacuum ,cleaning ,systems #aij ,,preface4 ,the contents of this work are compiled from the observations of the author through the seven years during which he has been engaged in the preparation of specifications for1 and the testing of1 complete plants installed in the buildings under the control of the ,treasury ,department4 ,during this time it has become necessary to alter no less than five times the stock form of specifications for stationary vacuum cleaning plants which were adopted by the ,government1 with the intent of obtaining the widest competition possible with efficient and economical operation1 in order to keep pace with the variation and improvement in the apparatus manufactured4 ,as each new type of system has come on the market a personal investigation at the factory1 together with tests1 has been made4 ,an exhaustive test of carpet renovators was also conducted1 using one of the ,government plants4 ,in addition the vacometers recommended for use in capacity tests were carefully calibrated1 using the machine at the ,department of ,agriculture4 ,the writer wishes to acknowledge the aid received from the various manufacturers in furnishing illustrations and data on their machines1 to ,messrs4 ,ewing ,ewing and ,prof4 ,sidney ,a4 ,reeve for data on tests made by ,prof4 ,reeve and used in defending the ,kenney basic patent4 ,in analyzing the results of his tests and observations1 the writer has endeavored to put his own conclusions into concrete form for the use of the consulting engineer and has not entered into the problems to be encountered in the design and manufacture of the various forms of apparatus4 ,,chapter ,i4 ,,history ,,of ,,mechanical ,,cleaning4 ,early ,attempts4--,whenever machinery has been introduced to assist or replace manual labor1 the earlier attempts have been in imitating the tools formerly used by man4 ,as the earliest mechanically-propelled carriages were mechanical walking machines1 the earliest steamboats mechanical rowing machines1 and the earliest flying machines mechanical birds1 so were the earliest mechanical cleaners in the form of mechanical brooms4 ,these mechanical brooms were introduced about #ahhj and took the form of the well-known street sweeper1 with a large circular brush mounted on a four-wheeled cart and rotated by means of gearing driven from the wheels1 the propelling power being the horses which drew the machine4 ,this machine at once made itself unpopular with the residents of the streets cleaned on account of its great activity in stirring up dust1 because the streets were swept dry4 ,this trouble was later overcome to a considerable extent by sprinkling the streets before sweeping1 but only at a sacrifice in efficiency of cleaning1 especially where such uneven surfaces as cobble or medina stone blocks formed the surface of the roadway4 ,various attachments were added to reduce this dust nuisance1 but none has apparently been successful1 as we see these machines in their original form in use today4 ,almost simultaneously with the introduction of the street sweeper came its counterpart1 the carpet sweeper1 with a similar but smaller brush1 enclosed in a wood and metal case1 the brush being driven by friction from the wheels supporting the box and the power for operation being derived from the person who pushed the machine along the floor4 ,this machine has not been modified to any great extent during the thirty odd years of its existence4 ,it is today in practically its original form1 and is doing no better work than when first introduced4 ,this form of mechanical cleaner occupied the field of household cleaning for nearly twenty years without a rival1 during which time it won its way into the hearts and hands of many housekeepers in this and other countries4 ,limitations of the ,carpet ,sweeper4--,this device1 with its light brush and equally light pressure on the surface cleaned and its limited capacity for carrying the material picked up1 has never been a thorough cleaner in any sense of the word1 and has been and is now used only to take up that portion of the usual litter and light dust which is located directly on the surface1 and is1 therefore1 most annoying to the housekeeper1 owing to its being visible to the eye4 ,because of its generous proportions1 made necessary to accommodate the material picked up1 and its centrally-pivoted handle1 made necessary by its mechanical construction1 it is impossible to operate it under low furniture4 ,like the lawn mower1 it must be in motion in order to operate its revolving brush1 on which its cleaning action is dependent4 ,it is impossible to make use of same in corners1 along walls1 or close to heavy furniture1 its use being limited to a literal slicking up of those portions of the carpet in the most conspicuous portions of the apartment4 ,in spite of these serious defects it came into1 and is still in1 nearly universal use1 even in households equipped with the latest approved types of mechanical cleaners4 ,its use on bare floors has never been even a moderate success and in no case has it superseded the broom and dust pan of our grandmothers4 ,compressed ,air ,cleaners4--,compressed air has been in use for many years in foundries and machine shops1 for cleaning castings and producing certain finishes on metal4 ,with the introduction of modern electrical machinery it was rapidly adapted to the cleaning of windings and other inaccessible parts of this machinery4 ,its first use in cleaning buildings was undoubtedly in the form of an open jet for dislodging dust from carvings and relief work1 for which purpose it is very efficient as a remover of the dust from the parts to be cleaned and also as a distributor of this same dust over the widest possible area for subsequent removal by other means4 ,it has a draw-back in that the expansion of air both cools the same and reduces its ability to retain moisture1 resulting in the deposit of moisture on the surfaces cleaned4 ,about #ahih1 attempts to overcome the objections to the open air jet and to produce a commercially successful compressed air carpet cleaner were undertaken almost simultaneously by two companies1 the ,american ,air ,cleaning ,company1 of ,milwaukee1 operating under the ,christensen patents1 and the ,general ,compressed ,air ,cleaning ,company1 of ,st4 ,louis1 operating under the ,thurman patents4 ,the renovator used by the ,american ,air ,cleaning ,company consisted of a heavy metal frame1 about #ah in4 long and #ab in4 wide1 having mounted on its longer axis a wedge-like nozzle extending the entire length of the frame1 with a very narrow slit1 in4 wide1 extending the entire length of its lower edge4 ,this nozzle was pivoted and so connected to the operating handle1 by which the renovator was moved over the floor1 that when the renovator was alternately pushed and pulled over the surface to be cleaned1 the slot was always inclined in the direction in which the renovator was being moved4 ,the top of the renovator was closed by a canvas bag1 smaller at the neck than in its center1 which was supported by a wire hook4 ,air was introduced into the nozzle1 at a pressure of from #de to #ee lbs4 per square inch1 and issued from the slot in a thin sheet which impinged on the carpet at an angle4 ,the frame was held close to the carpet by its weight1 preventing the escape of the air under its lower edge4 ,the air striking the carpet at an angle was deflected up into the bag1 inflating same like a miniature balloon4 ,the dust loosened from the carpet by the impact of the air was carried up into the bag where it lodged1 the air escaping through the fabric of the canvas into the apartment4 ,the renovator used by the ,general ,compressed ,air ,cleaning ,company differed from the above-described renovator in that it contained two nozzles1 with slots inclined at fixed angles to the carpet4 ,a pair of hand-operated valves were provided in the handle to introduce air into the nozzle which was inclined in the direction in which the renovator was moving2 otherwise the renovator was identical with that used by the ,milwaukee company4 ,these renovators were generally supplied with air from a portable unit1 consisting of an air compressor1 driven by a gasoline engine mounted with the necessary gasoline and air storage tanks on a small truck4 ,one of these machines was in use in ,washington last year1 but its use at that time was very limited and it is not to be seen this year4 ,these trucks were drawn up in front of the building to be cleaned and a large-size hose1 usually #a in4 in diameter1 was carried into the house and attached to an auxiliary tank from which -in4 diameter hose lines were carried to two or more renovators4 ,a few buildings were equipped with air compressors and pipe lines1 with outlets throughout the building for use with this type of renovator1 among which was the ,hotel ,astor in ,new ,york ,city4 ,these renovators1 the construction of which is shown diagrammatically in ,fig4 #a1 required approximately #ce cu4 ft4 of free air per minute at a pressure of from #de to #ee lbs4 per square inch and were usually driven by a #ae ,h4 ,p4 engine4 ,illustration3 ,,fig4 #a4 ,,early ,,type ,,of ,,mechanical ,,cleaning ,,nozzle ,,using ,,compressed ,,air4 ,the renovators were very heavy to carry about1 although their operation with the air pressure under them was not difficult4 ,however1 their operation was complicated1 requiring skilled operators4 ,owing to their generous proportions it was impossible to clean around furniture1 making its removal from the apartment necessary1 and limiting their use to the cleaning of carpets at the time of general house cleaning4 ,the cooling effect of the expansion of the air in the nozzle often caused condensation of moisture on the carpets when the relative humidity was high4 ,they were also at a disadvantage in that all the heavy dust collected in the canvas bag had to be carried from the apartment by hand4 ,owing to the constant agitation of the dust in the bag by the entering air currents1 much of the finer particles of dust and all the disease germs liberated by the renovator were blown through the bag back into the apartment4 ,they were not1 therefore1 by any means sanitary devices4 ,vacuum ,produced by ,compressed ,air4--,the ,general ,compressed ,air ,cleaning ,company also introduced another form of renovator for use with their compressed air plants4 ,this was composed of an ejector operated by compressed air1 with a short hose attached to a carpet renovator of the straight narrow-slot type1 such as was used later in vacuum cleaning systems4 ,the outlet from this ejector was connected by another short hose to a metal box containing a canvas bag1 woven backwards and forwards over metal frames to give a large surface for the passage of air4 ,the dust picked up by the suction of the ejector was carried with the air into the box and there separated from the air1 which escaped through the canvas into the apartment4 ,this form of renovator overcame some of the objections to the former type in that there was no condensation of moisture on the carpets1 and it was possible to operate the renovator under and around furniture1 and even on portieres and other hangings4 ,however1 the apparatus was rendered inefficient by the resistance of the bag1 causing a back pressure on the injector which greatly reduced its air-drawing capacity4 ,compressed ,air ,supplemented by ,vacuum4--,shortly after these two companies began operation1 the ,sanitary ,devices ,manufacturing ,company1 of ,san ,francisco1 introduced a new system of mechanical cleaning under the ,lotz patents4 ,this system used a renovator having a compressed air nozzle terminating in a narrow slot1 similar to the nozzles of the ,american and ,thurman systems1 but differing from them in that the slot was fixed vertically1 pointing downward4 ,this nozzle was surrounded by an annular chamber having an opening at the bottom of considerable width4 ,the whole formed a renovator about #ad in4 long and not over #b in4 wide at its base4 ,in addition to the compressed air connection to its nozzle1 a second hose1 #a in4 in diameter1 was connected to the annular space surrounding the nozzle and led to a vacuum pump by which the air liberated through the nozzle1 together with the dust which was liberated from the carpet1 was carried from the apartment4 ,the construction of this renovator is shown diagrammatically in ,fig4 #b4 ,illustration3 ,,fig4 #b4 ,,another ,,type ,,of ,,compressed ,,air ,,cleaning ,,nozzle1 ,,supplemented ,,with ,,vacuum ,,pipe4 ,as dust-laden air was not suitable to be carried through the pump used as a vacuum producer1 separators had to be provided to remove the dust from this air before it reached the pump4 ,the separators used consisted of two cylindrical tanks4 ,the air was introduced into the first tank in such a way that a whirling motion was imparted to it1 thus separating the heavier particles of dust by centrifugal force4 ,the second tank contained water which was brought into intimate contact with the air by means of an atomizer located in the pipe connection between the two tanks1 thus washing the air in a manner somewhat similar to the familiar air washers used in connection with mechanical ventilating systems4 ,the air and spray then entered the second tank1 above the water line1 where the entrained water separated on the reduction of velocity and fell back into the water below1 to be recirculated through the atomizer4 ,the air passed on out of the top of the tank to the pump4 ,an illustration of these separators is shown in ,fig4 #c4 ,illustration3 ,,fig4 #c4 ,,separators ,,used ,,with ,,combined ,,compressed ,,air ,,and ,,vacuum ,,machines4 ,illustration3 ,,fig4 #d4 ,,piston ,,type ,,of ,,vacuum ,,pump1 ,,mounted ,,tandem ,,with ,,air ,,compressor4 ,piston ,pump the ,first ,satisfactory ,vacuum ,producer4--,various types of apparatus were tried as vacuum producers1 including an air ejector1 such as was used with the ,thurman renovator1 and found to be ineffective due to its inability to overcome the back-pressure necessary to discharge the air through the hose1 which was placed on its outlet4 ,a rotary pump was next tried1 but1 owing to the selection of an inefficient type1 this was abandoned and1 finally1 a piston-type vacuum pump1 with very light poppet valves and mounted tandem with the air compressor1 was adapted and remained in use with this system until straight vacuum was adopted1 when the air compression cylinder was omitted4 ,this pump is illustrated in ,fig4 #d4 ,illustration3 ,,fig4 #e4 ,,mr4 ,,kenney',s ,,first ,,renovator1 ,,vacuum ,,alone ,,being ,,used ,,as ,,cleaning ,,agent4 ,in this system we see the first sanitary device to be introduced into the field of mechanical cleaning1 as the dust and germ-laden air were removed entirely from the apartment and purified before being discharged into the outside atmosphere4 ,the foulness of the water in the separators clearly showed the amount of impurities removed from the air4 ,these machines were mounted on wagons1 similar to their forerunners1 and were also installed in many buildings as stationary plants1 among which were the old ,palace ,hotel and the branch ,mint1 in ,san ,francisco1 and the old ,fifth ,avenue ,hotel1 in ,new ,york ,city4 ,systems ,using ,vacuum ,only4--,in #aijb ,david ,t4 ,kenney1 of ,new ,york1 installed the first mechanical cleaning system in which vacuum alone was used as the cleaning agent4 ,mr4 ,kenney used a renovator with a slot about #ab in4 long and in4 wide1 attached to a metal tube which served as a handle1 and to a -in4 diameter hose and larger pipe line leading to separators and vacuum pump4 ,mr4 ,kenney's first renovator is illustrated in ,fig4 #e4 ,illustration3 ,,fig4 #f4 ,,air ,,compressors ,,arranged ,,for ,,operation ,,as ,,vacuum ,,pumps4 ,mr4 ,kenney used as vacuum pumps commercial air compressors1 the first of which was installed in the ,frick ,building in #aijb and is illustrated in ,fig4 #f4 ,later he adapted the ,clayton air compressor1 with mechanically-operated induction and poppet eduction valves on larger sizes1 and single mechanically-operated induction and eduction valves on the smaller sizes4 ,the separators used by ,mr4 ,kenney differed from those used by the ,sanitary ,devices ,manufacturing ,company in that they contained several interior partitions1 screens1 and baffles1 and the air was drawn directly through the body of water in the wet separator4 ,the relative merits of these types of separators will be discussed in a later chapter4 ,illustration3 ,,fig4 #g4 ,,separators ,,installed ,,by ,,mr4 ,,kenney ,,in ,,frick ,,building4 ,the separators installed by ,mr4 ,kenney in the ,frick ,building1 and which are practically the same as were used by him as long as he manufactured vacuum cleaning apparatus1 are illustrated in ,fig4 #g4 ,after his application had been in the patent office for about six years he was granted a fundamental patent on a vacuum cleaning system4 ,renovator with ,inrush ,slot4--,the ,sanitary ,devices ,manufacturing ,company then produced a carpet renovator using vacuum only as a cleaning agent4 ,this cleaner has a wider cleaning slot than the cleaners usually furnished by ,mr4 ,kenney1 about in4 wide1 with a supplemental slot or vacuum breaker opening out of the top of the renovator and separated from the cleaning slot by a narrow partition extending nearly to the carpet1 as illustrated in ,fig4 #h4 ,the relative merits of these types of renovators will be discussed in a later chapter4 ,illustration3 ,,fig4 #h4 ,,vacuum ,,renovator ,,with ,,inrush ,,slot1 ,,introduced ,,by ,,the ,,sanitary ,,devices ,,manufacturing ,,co4 ,shortly after the introduction of vacuum cleaning by ,mr4 ,kenney and the ,sanitary ,devices ,manufacturing ,company1 the ,american ,air ,cleaning ,company published an interesting little booklet entitled1 8,compressed ,air ,versus ,vacuum10 which set forth in great detail the so-called advantages of compressed air over vacuum as a medium of mechanical carpet cleaning1 and1 apparently1 proved that vacuum cleaners were much less efficient than cleaners operated by compressed air4 ,a year or two later the ,american ,air ,cleaning ,company evidently had a change of heart and began to manufacture these same 8inefficient0 vacuum cleaners4 ,their previous treatise on vacuum cleaning1 which apparently was not copyrighted1 was republished by both the ,sanitary ,devices ,manufacturing ,company and by the ,vacuum ,cleaner ,company1 which had acquired ,mr4 ,kenney's patents1 and freely distributed4 ,thus this little work of the ,milwaukee company1 instead of injuring their competitors1 was turned into good advertising for them and required a lot of explanation from the ,milwaukee company4 ,steam ,aspirators ,used as ,vacuum ,producers4--,the ,american ,air ,cleaning ,company used a steam aspirator as its vacuum producer and1 unlike its predecessor1 the air-operated ejector1 it made good and has also been used to a limited extent by the ,sanitary ,devices ,manufacturing ,company4 ,it is now marketed by the ,richmond ,radiator ,company1 and its merits will be discussed in a later chapter4 ,the ,american ,air ,cleaner ,company also used as a vacuum producer the single-impeller type of rotary pump1 made by the ,garden ,city ,engineering ,company1 which was also later adopted1 to a limited extent1 by the ,vacuum ,cleaner ,company4 ,this will be discussed further on4 ,the renovator used by this company was a single-slot type1 with -in4 by #aj-;in4 cleaning slot4 ,these systems at once became notable on account of the small size of the vacuum producers used1 the low degree of vacuum carried1 and the vigorous campaign of advertising which was conducted4 ,several firms soon began to market vacuum cleaning systems almost identical with that of ,mr4 ,kenney1 among which were the ,blaisdell ,machinery ,company1 ,the ,baldwin ,engineering ,company1 and ,the ,general ,compressed ,air and ,vacuum ,machinery ,company1 the latter being the original ,thurman company4 ,the ,vacuum ,cleaner ,company then began a series of infringement suits against nearly every manufacturer of vacuum cleaning systems4 ,in nearly every case the suit has resulted in the offending company paying license fees to the ,vacuum ,cleaner ,company1 and this concern has now abandoned the manufacture of vacuum cleaners and has become a licensing company4 ,at this writing nearly twenty firms are paying license fees to the ,vacuum ,cleaner ,company and there is one suit now in the courts4 ,piston ,pump ,used ,without ,separators4--,a vacuum cleaning system of somewhat different design was produced by two former employees of the ,vacuum ,cleaner ,company1 ,mr4 ,dunn1 the once well-known 8,farmer ,dunn0 of the weather bureau1 afterward salesman for the ,vacuum ,cleaner ,company1 and ,mr4 ,locke1 at one time this firm's engineer4 ,this company was first known as the ,vacuum ,cleaning ,company1 and1 shortly afterward1 as the ,dunn-,locke ,vacuum ,cleaning ,company4 ,no separators were used with this system1 but the dust-laden air was led from the pipe lines directly into a chamber on the pump1 known as the 8saturation chamber10 and there mingled with a stream of water converting the dust into a thin mud4 ,the air1 water and mud then passed through the pump1 the muddy water was discharged into the sewer1 and the air into the atmosphere4 ,the vacuum producer used was a piston pump without suction valves4 ,with this system it was possible to handle water in almost unlimited quantities and with this feature a system of mechanical scrubbing was attempted for which great claims were made1 none of which1 however1 were realized in a commercial way4 ,these gentlemen sold their patents to the ,e4 ,h4 ,wheeler ,company1 which attempted to market the system in its original form4 ,it was found1 however1 that the piston pump was not adapted to the handling of grit which was picked up by the renovators1 and a rotary pump1 with single impeller and a follower was substituted4 ,this system is now marketed by the ,vacuum ,engineering ,company1 of ,new ,york1 and is known as the ,rotrex system4 ,mr4 ,dunn again entered the field of vacuum cleaning and began marketing his machine a short time ago with a new form of automatic separator discharging to sewer4 ,first ,portable ,vacuum ,cleaner4--,about #aije1 ,dr4 ,william ,noe1 of ,san ,francisco1 constructed the first portable vacuum cleaner4 ,this machine contained a mechanically-driven rotary brush1 similar to the brushes used in the familiar carpet sweeper1 for loosening the dust from the carpet4 ,this dust was sucked up by a two-stage turbine fan and discharged into a dust bag1 mounted on the handle1 similar to the bags on the compressed air cleaners4 ,the whole machine was mounted on wheels and provided with a small direct-connected motor4 ,this machine is illustrated in ,fig4 #i and is the original form of the well-known ,invincible renovator manufactured by the ,electric ,renovator ,company1 of ,pittsburgh4 ,this company now produces a complete line of stationary and portable vacuum cleaners1 all of which use multi-stage turbines4 ,the sale of the product of this company1 until recently1 was controlled by the ,united ,states ,radiator ,corporation4 ,illustration3 ,,fig4 #i4 ,,first ,,portable ,,vacuum ,,cleaner1 ,,constructed ,,by ,,dr4 ,,william ,,noe1 ,,of ,,san ,,francisco1 ,,in #aije4 ,first ,use of ,stationary ,multi-,stage ,turbine ,blowers4--,about #aije ,mr4 ,ira ,spencer1 president and engineer of the ,organ ,power ,company1 which manufactured a multi-stage turbine blower for organs1 known as the 8,orgoblow10 organized the ,spencer ,turbine ,cleaner ,company and marketed a vacuum cleaning system1 using a modification of the 8,orgoblow0 as a vacuum producer4 ,these machines were first constructed with sheet metal casings and had sheet steel fans1 with wings riveted on and mounted on horizontal shafts4 ,the separators were sheet metal receptacles with screens for catching litter4 ,light-weight hose1 #b in4 in diameter1 was used to connect the renovators to #d-;in4 sheet metal pipe lines4 ,a variety of renovators was produced for use with this system4 ,carpet renovators having cleaning slots varying from #aj in4 by in4 to #bj in4 by in4 were used1 and a very complete line of swivel joints for connecting the renovators and the hose to the handles was developed4 ,this system was operated at #e in4 vacuum1 which was much lower than that used by any other system1 #ae in4 being standard at that time1 and a much larger volume of air was exhausted under certain conditions than was possible with any of the then existing systems4 ,owing to the large volume of air exhausted and to the large size of the renovators1 hose and pipe lines1 larger articles could be picked up than was possible with any of the existing systems4 ,a great deal of weight was attached to this condition by the manufacturers1 a favorite stunt being to pick up nails1 washers1 waste1 small pieces of paper and even pea coal from a floor and finally to pick up a quantity of flour which had first been carefully arranged for the demonstration4 ,illustration3 ,,fig4 #aj4 ,,late ,,type ,,of ,,spencer ,,vacuum ,,cleaning ,,machine1 ,,operated ,,by ,,multi-,,stage ,,turbine ,,blower4 ,this invasion of the vacuum cleaning field was considered by the established manufacturers as a freak and the apparatus was christened 8the tin machine40 ,whenever it was installed in competition with other forms of cleaning systems1 the daily question asked by its competitors was1 8,has the tin machine fallen apart80 ,however1 the tin machine did not fall apart1 but held its own with the other systems1 even in its crude and inefficient state4 ,finding that the construction he had adopted was too flimsy and subject to abnormal leakage1 ,mr4 ,spencer developed a new form of machine1 using cast-iron casing and welded fan wheels and adopted standard pipe and fittings4 ,he also brought out a line of sheet metal tools and on the whole perfected a satisfactory cleaning system4 ,one of his machines of a later type is illustrated in ,fig4 #aj4 ,separators ,emptying to ,sewer by ,air ,pressure4--,a new form of vacuum cleaning system was introduced by ,mr4 ,moorhead1 of ,san ,francisco1 who used an inrush type of renovator having an inlet for air on each side of the cleaning slot4 ,the separator used with this system was a wet separator and contained a screen cleaned by a rotary brush into which all the dust contained in the air lodged4 ,the pump used with this system was generally of the piston type1 fitted with a single rotary valve1 so connected to the valve stem that it could be rotated thereon and the machine changed from a vacuum pump to an air compressor in order that the contents of the separators might be discharged into the sewer by air pressure when it was desired to empty same4 ,this system was marketed by the ,sanitary ,dust ,removal ,company1 of ,san ,francisco1 and1 later1 was taken over by the ,american ,rotary ,valve ,company1 of ,chicago1 which is now marketing same4 ,it eliminates the manual handling of the dust at any stage of its removal1 a feature which is made much of by its manufacturers1 but one which is likely to cause some trouble for the sewerage system if care is not exercised4 ,machines ,using ,root ,blowers as ,vacuum ,producers4--,the use of a ,root type of rotary pump as a vacuum producer was first undertaken by the ,foster and ,glidden ,engineering ,company1 of ,buffalo1 which marketed the ,acme system about #aijg1 the same company having previously built a similar system for the removal of grain from steam barges4 ,the other features of this system did not differ materially from those already on the market4 ,being familiar with the various uses to which this type of vacuum pump had been adapted1 the principal one being the operation of pneumatic tube systems1 the author suggested the use of this type of vacuum producer about two years previous to its introduction and was advised by one manufacturer that such a type of pump was not suitable for vacuum cleaning4 ,the fallacy of this statement will be brought out in detail in a later chapter4 ,the type of vacuum producer just described has been adopted in many makes of vacuum cleaners1 including the ,hope1 ,connellsville1 ,arco1 and1 lately1 in the ,american ,rotary ,valve ,company's smaller systems4 ,during the past four years a score or more of new stationary vacuum cleaning systems have been introduced1 among which are the ,palm1 a modification of the ,dunn-,locke system2 the ,tuec1 a turbine cleaner2 the ,water ,witch1 which uses a water-operated turbine as a vacuum producer1 and the ,hydraulic1 with water-operated ejector4 ,at the same time a hundred or more portable vacuum cleaners have been marketed4 ,these are of almost every conceivable type and form and are operated by hand1 electricity1 and water power4 ,among them will be found machines which are good1 bad and indifferent1 the efficiency and economy of which will be discussed in a later chapter4 ,this nearly universal invasion of the vacuum cleaner field by anybody and everybody looking for a good selling article1 establishes the fact that the vacuum cleaner is not a fad or fancy1 but has become almost a household necessity and has led large corporations to take it up as a branch of their business4 ,first1 the ,sanitary ,devices ,manufacturing ,company and the ,vacuum ,cleaner ,company1 the pioneers in the field1 after a legal battle of years1 consolidated with a view of driving their competitors from the field as infringers of the patents controlled by the two organizations4 ,the result of this was the licensing of other companies4 ,in an attempt to control the sale of their type of apparatus notice was served on all users of other types of vacuum cleaners that they were liable to prosecution for using infringing apparatus4 ,later1 the ,mc,crum-,howell ,company1 a manufacturer of heating boilers and radiators1 secured control of the products of the ,american ,air ,cleaning ,company and the ,vacuum ,cleaner ,company and sold these machines to the trade for installation by the plumbers and steam fitters4 ,the ,mc,crum-,howell ,company has been succeeded by the ,richmond ,radiator ,company1 which is handling these vacuum cleaning machines4 ,shortly afterwards1 the ,united ,states ,radiator ,corporation secured control of the ,invincible and the ,connellsville systems1 and1 lastly1 the ,american ,radiator ,company secured the ,wand system4 ,thus we see that vacuum cleaning seems to be virtually in the control of the manufacturers of heating apparatus1 who are also among the largest corporations in this country and well able to control the future of this business to their liking4 ,as to the future of vacuum cleaning the author considers that it is at present1 like the automobile1 at the height of its career1 and also1 like the automobile1 that it is a useful appliance to mankind and that it has its proper place as a part of the mechanical equipment of our modern buildings4 ,as to the type of vacuum cleaner of the future1 the author believes that these appliances will become standardized1 just as all other useful appliances have been1 and that the form that it will then take will be a survival of the fittest4 ,what that form may resemble the reader may more readily judge when he has completed the reading of this book4 ,,chapter ,,ii4 ,,requirements ,,of ,,an ,,ideal ,,vacuum ,,cleaning ,,system4 ,before a comparison of the relative merits of any line of appliances1 used for any one purpose1 can be intelligently made1 one must have either some form of that apparatus which we consider as a standard for comparison that we may rate all others as inferior or superior thereto1 or else an ideal of a perfect system must be assumed1 and the measures with which each of the various appliances approaches the requirements of the ideal will establish their relative merits4 ,the author has elected to use the latter method in comparing the various systems of vacuum cleaning1 and it is necessary1 therefore1 to first determine what are the requirements we shall impose on the ideal system4 ,an ideal vacuum cleaning system would be one which1 when installed in any building1 will displace all appliances used for dry cleaning in the semi-annual renovating or house cleaning1 the weekly cleaning or ,friday sweeping and the daily supplemental cleaning4 ,if our system be truly an ideal one1 the premises should never become so dirty as to require any semi-annual cleaning at all1 and1 if the daily cleaning be anyway thorough1 there need be no weekly cleaning4 ,this latter condition may be governed by the will of the housekeeper or janitor4 ,the compressed air cleaners first introduced were intended for use only at the semi-annual cleaning and they were in reality carpet renovators1 which were assumed as imparting to the carpets all the beneficial results that could be obtained by taking them up and sending them to a carpet-cleaning establishment1 with the advantage over this latter method1 that the labor of removal and replacement of the carpets was rendered unnecessary1 but with the disadvantage that all the germ-laden air1 used as a means of cleaning the carpets1 was blown back into the apartment1 leaving the germs in their former abode4 ,this disadvantage1 however1 is partly offset by the fact that while the majority of the germs in one's own carpet are blown out at the carpet cleaners1 a mixed company of germs from your neighbors' and others' carpets1 which may be in the tumbling barrel at the same time with your own1 are returned to you with your carpet4 ,neither of these conditions is ideal and we will expect our ideal cleaner to completely remove from the premises1 not only the dust and dirt1 but also the germ-laden air which is used as a means of conveying this dirt4 ,for replacing the weekly and the daily cleaning1 these earlier renovators were not suitable1 as in order to use same the furniture must all be removed from the apartment4 ,to accomplish this daily and weekly cleaning1 the ideal vacuum cleaner must replace the broom and dust pan1 and their inseparable companion1 the duster1 and must also supersede that time-honored mechanical cleaner1 the carpet sweeper4 ,the reader will doubtless consider that in making this statement the author is asking the vacuum cleaner to perform much more than it is usually called on to do4 ,however1 we are now discussing an ideal system1 and the above requirements are not absolutely beyond what can be accomplished by some of the cleaning systems now on the market4 ,to accomplish this requirement the ideal cleaner must pick up everything likely to be found on the floor which cannot be readily picked up by hand4 ,the character of this material will vary greatly according to the uses of the apartment cleaned4 ,in residences and offices1 where carpets or rugs are in use1 cigar stumps and matches are usually deposited in cuspidors and small pieces of paper in waste baskets1 consequently there should be nothing but dust to be removed from a residence and1 perhaps1 mud and sand from the shoes of the many visitors1 in addition to the dust in an office4 ,however1 there are special conditions likely to be met in many cases2 sewing rooms will be littered with basting threads and scraps of cloth2 department stores1 with a great quantity of pins2 banking rooms with bands and large-sized bank pins2 all of which increase the requirements of the ideal system4 ,a cleaner which is perfectly adapted to one sort of apartment will be entirely unsuited for another1 and the ideal cleaner will be one which can be readily adapted to all conditions likely to be met in the building in which it is installed4 ,the ideal cleaner must be able to accomplish the above stated requirements without the necessity of moving heavy pieces of furniture out of or about the apartment2 that is1 it must be capable of being efficiently operated under beds1 tables and chairs1 around the legs of other heavy furniture1 behind bookcases1 pianos1 cabinets1 etc41 over curtains1 draperies and hangings1 over walls1 behind pictures and over mouldings and carved ornaments1 all without injury to any of the furniture or fittings of the apartment1 and with the least expenditure of energy by the operator4 ,these conditions should be met with the fewest possible number of cleaning appliances1 none of which should be provided with small attachments liable to be lost or misplaced1 and all parts of the system1 which must necessarily be moved about1 either before1 after or during the cleaning operation1 should be of minimum weight and bulk1 but of rugged and lasting construction4 ,the ideal vacuum cleaner should be of such proportions and provided with ample motive power to clean rapidly and effectively4 ,for use in an office building the cleaner should be able to thoroughly clean an average-sized office1 including floor1 walls1 furniture and fittings in from #aj to #ae minutes1 and for residence work1 should be of sufficient capacity to clean an apartment1 including floor1 walls1 curtains1 draperies1 pictures and furniture in not exceeding #cj minutes4 ,the ideal system should be so arranged that any apartment in the building can be cleaned with the least possible disturbance and without affecting the use of any other apartment1 excepting perhaps1 the corridors or hallways4 ,in large offices1 drafting rooms and similar apartments1 it may become necessary to clean same while they are occupied2 therefore1 our ideal system must be practically noiseless in operation and must offer the least possible obstruction to the proper use of the room by its regular occupants4 ,necessity and ,proper ,location of ,stationary ,parts4--,to be of sufficient power to do rapid cleaning and in order to remove from the building all dust and germ-laden air1 the cleaning system must necessarily contain some stationary parts4 ,the motive power can generally be confined to these stationary parts1 and must1 in such cases1 be located within the building to be cleaned4 ,therefore1 it should operate with the minimum of noise and vibration4 ,machines located in office or other large buildings1 containing elevators or other complicated apparatus requiring skilled attendance1 which are provided with complicated control and with other attachments1 are not objectionable1 and in such cases simplicity should give way to efficiency1 but unnecessary complications should be avoided4 ,in residences and other small buildings1 where the vacuum cleaner is likely to be the only machinery installed1 the system must be one which requires the minimum attention and must be capable of being started and stopped by any person of average ability1 without the necessity of going to the point where the machine is located4 ,the power consumption of the ideal system should be a minimum to accomplish satisfactory results and should be1 as nearly as possible1 directly proportioned to the amount of cleaning being done4 ,this requirement is most important in hotels1 where some cleaning is likely to be done at all hours1 day and night4 ,in other words1 vacuum must be 8on tap0 and as readily attainable at any point in the building as your water or electric light4 ,in office buildings1 where a schedule of cleaning hours is fixed1 and in residences where cleaning hours are few and the capacity of the plant is rarely more than could be attended to by one operator1 this requirement is not of as great importance4 ,lastly1 our ideal system1 from the standpoint of the purchaser1 must be of such rugged construction1 as will enable it to operate efficiently for1 at least1 ten years and its mechanical details such that it will operate continuously1 without expert attention1 and that the annual expense for repairs during the life of the machine will not exceed #e of the first cost of the system4 ,,chapter ,,iii4 ,,the ,,carpet ,,renovator4 ,in undertaking the comparison of a number of different makes of any appliance1 in order to determine the good and bad points in each1 where the apparatus is composed of a number of separate and distinct parts1 each having its proper function1 which they must perform in order to make the whole apparatus effective1 as in a vacuum cleaning system1 it becomes necessary to isolate temporarily each part and consider its action1 first1 as a unit working under the most favorable conditions1 and1 second1 as a component part of the whole apparatus in order to determine where the weak points in any system occur and what modifications are necessary in the various parts of the apparatus to make some vital part of the whole more effective4 ,it is further necessary to determine what are the vital parts of the system in order that the other parts may be accommodated to the effective action of that part4 ,four ,important ,parts of ,vacuum ,cleaning ,system4--,in analyzing a vacuum cleaning system it naturally divides itself into four parts1 viz43 the cleaning tool or renovator1 the air-conveying system or hose and pipe lines1 the separators or other means of disposal of the material picked up1 and the vacuum producer4 ,the author considers that the renovator is the most important part of the system and that the other parts should be made of such proportions and with such physical characteristics as will produce the proper conditions at the renovator to permit it to perform its functions in the most effective manner4 ,as the vacuum cleaning system must be capable of cleaning surfaces of a widely variable character many forms of renovators are necessary4 ,of the various surfaces cleaned the author considers that carpets and rugs comprise the most important1 as well as the most difficult to clean effectively1 so that the carpet renovator will be considered first4 ,the ,straight ,vacuum ,tool4--,various forms of carpet renovators have been and are in use by manufacturers of vacuum cleaning systems4 ,the first type of renovator to be considered is that having a cleaning slot not over #ab in4 long1 with its edges parallel throughout its length1 and not over in4 wide1 with a face in contact with the carpet not over in4 wide on each side of the slot4 ,this form of renovator is illustrated in ,fig4 #aa and is designated by the writer as ,type ,a4 ,the first of these renovators was introduced by ,mr4 ,kenney and1 as finally adopted by him1 was #ab in4 long1 with -in4 face and with a cleaning slot #aa in4 long and in4 wide4 ,this form of cleaner was termed the 8straight vacuum tool0 and is used today by many manufacturers4 ,slight modifications in its form and dimensions were made in some cases1 as in the one manufactured by the ,american ,air ,cleaning ,company4 ,in the one used in all tests by the writer on type ,a renovators1 the slot was reduced to #aj in4 long and in4 wide and the face of the renovator was slightly rounded at the outer edges1 leaving very little surface in contact with the carpet4 ,illustration3 ,,fig4 #aa4 ,,type ,a1 ,,the ,,straight ,,vacuum ,,tool4 ,illustration3 ,,fig4 #ab4 ,,type ,b1 ,,with ,,wide ,,slot ,,and ,,wide ,,bearing ,,surface4 ,a renovator of this type is easily operated over any carpet even when a considerable degree of vacuum exists within the renovator itself4 ,it has met with favor when used with the piston type of vacuum pump without vacuum control1 as was the case with the earlier systems4 ,however1 when a very high degree of vacuum occurs within the renovator it has a tendency to pull the nap from the pile of the carpet4 ,soon after the introduction of this form of renovator1 some users of same1 particularly in ,san ,francisco1 complained that while the renovator effectively removed the dust from carpets it failed to pick up matches and other small articles and preliminary or subsequent cleaning was necessary in order to remove such litter4 ,to overcome this difficulty ,mr4 ,kenney increased the width of the cleaning slot to nearly in41 with the result that when a high degree of vacuum existed within the renovator1 which often occurred where no vacuum control was used1 it stuck to the carpet1 rendering its operation difficult and1 at the same time1 doing great damage to the carpet4 ,hence1 its use with the piston type of vacuum pumps was abandoned4 ,mr4 ,kenney then modified this wide slot renovator by making the face of same much wider1 thus having more surface in contact with the carpet on each side of the slot1 preventing the renovator from sinking into the nap of the carpet4 ,this type of renovator is illustrated in ,fig4 #ab and has been designated as ,type ,b4 ,while not as destructive to the carpets1 when a high degree of vacuum existed under the same1 it still pushed hard and was not as rapid a cleaner as the narrow-lipped ,type ,a renovator4 ,renovator with ,auxiliary ,slot ,open to ,atmosphere4--,the renovator introduced by the ,sanitary ,devices ,manufacturing ,company differed widely from the former types in that it was provided with an auxiliary slot1 open to the atmosphere through the top of the renovator1 which communicated with the slot open to the vacuum by a space of -in4 under the partition separating the slots4 ,the cleaning slot was made -in4 wide and the face of the renovator was made #b-;in4 wide1 which gave a contact of -in4 in front of the inrush slot and -in4 in the rear of the cleaning slot4 ,this form of renovator is illustrated in ,fig4 #ac and is designated as ,type ,c4 ,the auxiliary slot or vacuum breaker permitted air to enter the cleaning slot even when the renovator was placed on a surface plate1 and1 owing to this feature1 a high degree of vacuum never existed within the renovator4 ,it was always easy to operate and did not damage the carpet4 ,owing to the wide slot1 articles of considerable size could be picked up1 and there was always an abundance of air passing through the renovator to produce a velocity in the hose and pipe lines sufficient to carry any heavy articles picked up4 ,the vacuum producer1 control apparatus and the proportions of the hose and piping used at that time made the degree of vacuum in the renovator a function of the quantity of air passing1 with wide limits of variation under existing conditions1 and this form of renovator is practically the only one which will do effective cleaning1 including the picking up of litter1 without undue wear on carpets1 when used with a system having the above-stated characteristics4 ,this renovator1 however is not without its faults4 ,owing to the wide surface in contact with the carpet1 a considerable degree of vacuum is necessary in order that any air shall enter the renovator under the faces of same and1 as the air entering the inrush slot prevents the formation of such vacuum within the renovator1 very little air enters the renovator between its face and the carpet4 ,when the renovator is operated on a carpet having a glue-sized back1 no air enters through the carpet1 therefore all air entering the renovator must come through the inrush slot and under the partition separating same from the cleaning slot4 ,under these conditions only one side of the vacuum slot is effective and this effective side is raised above the surface of the carpet4 ,illustration3 ,,fig4 #ac4 ,,type ,c1 ,,with ,,auxiliary ,,slot1 ,,open ,,to ,,atmosphere4 ,illustration3 ,,fig4 #ad4 ,,type ,d1 ,,with ,,two ,,cleaning ,,slots4 ,when operated on an ingrain or other loose-fabric carpet1 much air enters through the fabric of the carpet1 due to the wide cleaning and inrush slots1 in addition to the quantity of air entering through the inrush slot1 making this renovator1 when operating under these conditions1 use an unnecessary amount of air4 ,apparently1 this renovator has been designed to prevent the formation of any great degree of vacuum under same and such a design has resulted in a greater volume of air at a lower vacuum passing through than through renovators of other types4 ,this property of the renovator raises the question whether the quantity of air or the degree of vacuum in the renovator is most essential for the removal of dirt from carpets4 ,tests made by ,mr4 ,s4 ,a4 ,reeve1 consulting engineer for the ,vacuum ,cleaner ,company1 with this type of renovator1 with the inrush open and repeated with the inrush closed1 disclose the fact that it does more effective cleaning with its inrush closed1 while the volume of air passing is considerably less with the inrush closed4 ,the degree of vacuum was greater1 which tends to indicate that the vacuum within the renovator is the most important factor4 ,an extract from the affidavits of ,mr4 ,reeve in one of the numerous patent suits will show his explanation of this phenomenon3 8,if we examine more closely into the actual process whereby such a sweeper succeeds in extracting dust from carpets1 etc41 it will appear that the actual cleaning is effected at the periphery of the slot in the lower surface of the sweeper4 ,it is accomplished chiefly by the development of local changes of air pressure at the lips defining this slot1 incidentally to the movement of the tool over the carpet4 ,these changes cause the air occupying the interstices between the dust particles to expand suddenly1 thus #8raising the dust4' ,to a lesser degree1 the scouring is effected by highly localized air currents of considerable velocity1 engendered where the tool comes in contact with the carpet4 ,these air currents pick up the dust which has already been expanded or raised by pressure change4 ,they will be of higher velocity1 and therefore more effective1 the better the contact of the tool with the carpet4 ,the same is true of the pressure changes4 8,all this action depends for its intensity1 speed and effectiveness1 not on the vacuum existing at the pump or in the separators1 but upon the vacuum prevailing within the sweeper head itself40 ,renovator with ,two ,cleaning ,slots4--,another form of renovator was introduced by the ,blaisdell ,machinery ,company which contained two cleaning slots each -in4 wide and #ab-;in4 long1 separated by a partition -in4 wide in contact with the surface of the carpet1 as indicated in ,fig4 #ad 7,type ,d74 ,while this form of renovator has a greater area of cleaning slot than ,type ,a1 its individual cleaning slots are no wider2 therefore1 it cannot pick up anything larger than can be picked up by ,type ,a4 ,as no air can enter under the partition it can do no more effective work as a dust remover when operated on a carpet with a glue-sized back and its only advantage over a cleaner of ,type ,a is that when operated on a loose-fabric carpet more air can pass through the fabric into the cleaning slot1 thus giving a greater variation in the quantity of air exhausted when operated on carpets of different texture1 a condition which is undesirable when used with a system having characteristics previously described4 ,tests of this type of renovator1 made by ,mr4 ,reeve1 are given later in this chapter4 ,renovator with ,inrush ,slots on ,each ,side4--,another form of renovator1 introduced by ,mr4 ,moorhead1 is illustrated in ,fig4 #ae 7,type ,e74 ,this is a modification of ,type ,a in that an inrush slot is provided on each side of the vacuum slot1 these inrushes being hinged members which form the sides of the cleaning slot4 ,this cleaner has the advantage over ,type ,c renovator in that it can take air from either side1 but in action it takes air from but one side at any time4 ,its inrush will not become entirely clogged1 but its mechanically-moving parts in contact with the dust and lint picked up will easily become inoperative and are as like as not to become caught wide open when the air entering the cleaner will not come into intimate contact with the carpet4 ,in that event1 its cleaning efficiency will be greatly reduced4 ,the author has not had an opportunity to make any comparative tests of this form of renovator4 ,when ,mr4 ,spencer introduced the centrifugal fan as a vacuum producer1 he also brought out a series of carpet renovators of various forms and sizes4 ,one had a cleaning slot -in4 wide and #aj-;in4 long1 another a slot #ae-;in4 long1 -in4 wide at its end1 increasing to -in4 at the center4 ,another had a slot #bj-;in4 long and -in4 wide1 and finally he adopted a tool with a cleaning slot #ae-;in4 long and -in4 wide throughout its length4 ,this is merely the re-entrance into the field of the wide-slot tool first used by ,mr4 ,kenney and its successful operation depends on its use with a vacuum producer of such characteristics and a hose and pipe line of such proportions that practically a constant vacuum is maintained within the renovator1 regardless of the quantity of air passing through the tool4 ,the latest form of this renovator1 as used by ,mr4 ,spencer1 is illustrated in ,fig4 #af4 ,at the time that the writer made tests on renovators of this make1 the majority of the tests were made with a renovator having a cleaning slot #aj-;in4 long and -in4 wide4 ,this renovator is designated as ,type ,f1 while the #ae-;in4 -in4 to -in4 slot is designated as ,type ,f4 ,illustration3 ,,fig4 #ae4 ,,type ,e1 ,,with ,,inrush ,,slot ,,on ,,each ,,side ,,of ,,vacuum ,,slot4 ,illustration3 ,,fig4 #af4 ,,type ,f1 ,,an ,,exaggerated ,,form ,,of ,,type ,b4 ,about seven years ago the ,supervising ,architect of the ,united ,states ,treasury ,department gave consideration to the use of a carpet cleaning test to determine the acceptability of any vacuum cleaning system which might be installed in any of the buildings under his control4 ,the author was instructed to make a series of tests of carpet renovators1 with a view of determining3 7#a7 the feasibility of using a carpet cleaning test to determine the merits of a vacuum cleaning system2 7#b7 to fix the requirements to be incorporated in a specification where the acceptance of the system was dependent on a satisfactory carpet cleaning test1 to be made at the building after the completion of the installation2 7#c7 to determine what requirements1 other than a cleaning test1 would be necessary to obtain a first-class cleaning system4 ,the record of many such tests was shown to the author1 shortly before he began making tests4 ,these purported to have been made by ,prof4 ,miller at the ,massachusetts ,institute of ,technology1 with a pump furnished by the ,sanitary ,devices ,manufacturing ,company1 in which the efficiency of the inrush type of renovator 7,type ,c7 and the straight vacuum renovator 7,type ,a7 was compared4 ,the results of these tests1 as given in a brief resum1 which was distributed by the ,sanitary ,devices ,manufacturing ,co41 indicated that the ,type ,c renovator was the more rapid and efficient cleaner4 ,the author learned that these tests were made by the undergraduate students as a part of the regular laboratory work1 and that later a series of tests was made as the basis of a thesis by ,messrs4 ,paterson and ,phelps in #aijf1 using the above-described apparatus4 ,the following year another series of tests was made by ,mr4 ,stewart ,r4 ,miller1 as the basis of an undergraduate thesis1 in which the efficiencies of the piston pump and inrush sweeper of the ,sanitary ,devices ,manufacturing ,co4 were compared with those of the steam aspirator and straight vacuum renovator of the ,american ,air ,cleaner ,company4 ,a copy of this thesis was furnished the author by the ,sanitary ,devices ,manufacturing ,company shortly after the completion of the tests made by the author4 ,the relative efficiency of the two types of renovators reported by these tests differed widely in each case1 an occurrence which is liable to happen where undergraduate students are engaged in such work4 ,they were1 therefore1 considered as of doubtful reliability4 ,the author could find no record of any tests made by anyone of longer experience and1 indeed1 these were the only tests of which he could find any record4 ,as the author desired to specify a cleaning test which could be readily repeated at the building in which the cleaning system was installed1 which building was likely to be located in any part of the ,united ,states1 no exhaustive laboratory methods were desired or attempted4 ,as the building was likely to be located in a city where no other vacuum cleaning systems were then installed and in a new building in which no dirty carpets were available1 and as it was not desirable to have the contractor furnish the material for the test1 it was considered necessary to use some material in soiling carpets which would be readily obtainable anywhere1 which could be readily brought to a standard1 and which1 when worked into the carpets in a reasonable length of time1 would be as difficult to remove as the dirt found in the average dirty carpet4 ,tests on ,dirty ,carpets4--,as no tests of cleaning an actually dirty carpet were on record1 quicksand having been used in the ,institute of ,technology tests1 it was necessary to first clean some carpets that had been soiled in actual daily service in order to obtain a standard with which to compare the results in removing various substances1 which it was intended to try as a substitute for dirt4 ,a carpet which had been in actual use for a number of years on the floors of the old ,united ,states ,mint building1 in ,philadelphia1 and receiving the ordinary amount of cleaning1 was procured4 ,this was a ,brussels carpet with a glue-sized back1 containing about #bj sq4 yds4 ,it was divided into three approximately equal parts4 ,an indicator was attached to the vacuum pump for taking air measurements1 and it was found that there was considerable leakage of air into the system through the connections to the separators and at other points1 therefore the pump was operated with #bb in4 of vacuum in the separator and a card taken with all outlets closed and the amount of leakage noted4 ,during the tests this degree of vacuum was always maintained in the separators and pipe lines and the vacuum in the renovator was varied throughout the tests by throttling the hose cock4 ,this manner of making tests gave a practically constant leakage which was deducted from the quantities shown by the indicator cards taken with the renovators in operation4 ,as the writer had already made many tests of the efficiency of various types of vacuum pumps as air movers under various degrees of vacuum1 and as the capacity of the pump available was far in excess of that required to operate one renovator1 no attempt to obtain the efficiency of the plant as a unit was made4 ,instead1 the vacuum at the hose cock was adjusted until the degree obtained was what the writer had found to be within the limit obtained in practice4 ,the resulting vacuum at the renovator was then noted4 ,each piece of carpet was cleaned during six periods of one minute each1 using a different vacuum at the tool for each piece of carpet4 ,the carpets were weighed at the beginning of the test and after each one-minute period4 ,at the conclusion of these tests each carpet was cleaned until no change of weight occurred after two minutes' cleaning4 ,they were then considered as being #ajj clean and this standard was made a basis for computing the percentage of dirt removal4 ,a renovator of ,type ,c was used in these tests4 ,shortly afterward a similar test was made on a dirty carpet of #d4f sq4 yds4 area1 using a renovator of ,type ,f4 ,this carpet was also a ,brussels1 with glue-sized back1 which had been in use in the shoe department of a large department store in ,hartford4 ,these carpets contained approximately #b oz4 of dust per square yard1 none of which was visible on the surface1 and they were probably as clean as the average carpet after being gone over with a carpet sweeper or after a light application of a broom4 ,,table #a4 ,,cleaning ,,tests ,,of ,,dirty ,,carpets4 ---------------------------------------- ------------------------- ,type of ,renovator4 ,a ,c ,f ---------------------------------------- ------------------------- ,vacuum in renovator1 in4 ,hg #b #d #a #b #d #c ,air exhausted1 cu4 ft4 per min #af #bg #bd #cg #dd #ei ,material removed1 per cent4 of total1 #a min4 #ej #fj #cg #ci #dg #ce ,material removed1 per cent4 of total1 #b min4 #gb #ha #eb #ei #fc #ee ,material removed1 per cent4 of total1 #c min4 #he #ij #ei #ff #ga #fi ,material removed1 per cent4 of total1 #d min4 #ij #ie #fa #gb #hc #gg ,material removed1 per cent4 of total1 #e min4 #ic #ih #ff #ge #hg #hd ,material removed1 per cent4 of total1 #f min4 #ie #ajj #fg #hb #ij #hi ,h4 ,p4 per ounce dust #j4jcg #j4adg #j4jde #j4aaf #j4bebj4bfa ,ounces dust per minute #a4i #b4j #a4cd #a4fd #a4h #a4gh ,h4 ,p4 at renovator #j4jg #j4bi #j4jf #j4ai #j4de #j4dge ---------------------------------------- ------------------------- ,as the sizes of the carpets used in making the tests were not always the same1 allowance has been made for this variation by using1 in the case of ,type ,f renovator1 instead of the true time1 a calculated time which allows each renovator the same time for cleaning #a sq4 yd4 of carpet4 ,for instance1 in the case of the small carpet cleaned with ,type ,f renovator1 an interval of #fj #d4f #f1 or #df seconds1 was taken as equal to one minute's cleaning of the carpet with types ,a and ,c renovators4 ,such interval is stated and plotted as one minute in the table opposite1 which gives the results of cleaning dirty carpets with the three types of renovators4 ,type ,a ,renovator ,most ,efficient on ,dirty ,carpets4--,the results of the tests of the three types of renovators1 each when it was operated with the highest vacuum under the renovator1 are plotted in ,fig4 #ag in order that a ready comparison may be made4 ,this curve indicates that ,type ,a renovator does more effective cleaning in less time than either of the other two types tested4 ,illustration3 ,,fig4 #ag4 ,,tests ,,of ,,three ,,renovators ,,on ,,dirty ,,carpets4 ,referring to the second line of the table1 which gives the degree of vacuum obtained in the renovator during the tests1 it will be noted that the highest vacuum attained with each type of renovator is practically the same4 ,this degree of vacuum was obtained with the average vacuum at the hose cock1 using #ajj ft4 of hose in each case1 and corresponds to that obtained in the commercial operation of each of the renovators with the vacuum producers ordinarily used1 which was #ae in4 in the case of ,type ,c1 #aj in4 in case of ,type ,a1 and #e in4 in case of ,type ,f1 the hose being the size used by each of the systems as marketed4 ,the third line1 which shows the cubic feet of free air per minute passing the renovator1 indicates that ,type ,a renovator requires much less air at the same degree of vacuum than either of the other types to do better work4 ,from the readings in these two lines the horse power required at the renovator1 to move the air that passes same is obtained with #ajj efficiency adiabatic compression4 ,the results are tabulated in the ninth line of the table4 ,this indicates that ,type ,a renovator does more effective work with about #ej of the power required by either of the other types of renovators4 ,the tenth line gives the rate of cleaning and again shows ,type ,a renovator to be the most rapid cleaner4 ,the eleventh line gives the horse power required at the renovator when in operation1 from which it will be seen that effective cleaning cannot be accomplished with less than ,h4 ,p4 at the renovator4 ,attention is called to the great reduction in power in case of ,type ,a renovator when the vacuum at the tool is reduced from #d in4 to #b in4 and to the small reduction in the efficiency which results from this great reduction in power4 ,this is not the case with the ,type ,c renovator1 where there is a considerable reduction in the already low efficiency with each reduction in the vacuum4 ,this characteristic of ,type ,a renovator is discussed further on in the chapter on hose4 ,tests of ,carpets 8,artificially0 ,soiled4--,having determined the efficiency of the various types of renovators when operated on dirty carpets1 the author then attempted to find some substance easily obtained anywhere which could be used as a substitute for actual dirt1 and which would give approximately equal results with these obtained on dirty carpets4 ,a test of this character was made by the author some time previous to the tests of dirty carpets and was made on a ,wilton velvet rug of about #ab sq4 yds4 area4 ,the material spread on same was ordinary wheat flour1 as used in demonstrations1 #c lbs4 of which were placed on the rug and rubbed in with sticks of wood as well as possible and the rug cleaned for three minutes1 using a ,type ,a renovator attached to the separator with #ej ft4 of #a-;in4 diameter hose4 ,the results were as follows3 ,,vacuum ,,at ,,separator1 ,,per ,,cent4 ,,dirt ,,ins4 ,,mercury4 ,,removed4 #e #ie #aj #ih #ae #ih ,the vacuum at the renovator was not measured at the time of making this test and its amount is not exactly known1 but further tests with this type of renovator under nearly the same conditions gave the following results3 ,,vacuum ,,at ,,hose ,,cock1 ,,vacuum ,,in ,,renovator1 ,,ins4 ,,mercury4 ,,ins4 ,,mercury4 #e #c #aj #f #ae #i and it is probable that the vacuum at the renovator during these tests was approximately the same4 ,comparison of the results of this test1 in which #d sq4 yds4 of carpet were cleaned per minute1 with those of the tests of dirty carpets1 in which only #a sq4 yd4 was cleaned per minute1 indicates that wheat flour is not a suitable substitute for dirt in making a carpet cleaning test4 ,the author1 believing that flour is of sufficient fineness1 but not of sufficient weight1 tried ,portland cement1 which is very heavy and at the same time exceedingly fine1 as a substitute for dirt in soiling carpets4 ,the same carpet that had been cleaned in ,philadelphia was used and #f oz4 of cement was worked into the same4 ,it was then cleaned with a ,type ,c renovator1 with a vacuum of #b in4 hg4 at the renovator and #ie of the cement was removed in two minutes' cleaning1 as against #ei of the dirt in the carpet when received4 ,ordinary dirt1 taken from some flower pots which had been left dry for some time1 was then tried with the same carpet1 using a ,type ,c renovator and #a in4 hg4 ,with this arrangement1 #ga of the dirt was removed in two minutes as against #eb of the dirt in the carpet as received4 ,this dirt was then mixed with water to a thin mud and spread over the carpet and the carpet dried before cleaning4 ,then #aa oz4 of this material was worked into #f sq4 yds4 of carpet and a ,type ,c renovator removed #ajj of this in four minutes' cleaning1 with a vacuum of #b in4 hg4 at the tool as against #gb of the dirt in the carpet as received4 ,the author's ingenuity being about exhausted1 he referred to the test of ,mr4 ,stewart ,r4 ,miller in which quicksand which would pass a #ej-mesh to the inch screen was used1 a long-napped ,brussels carpet being filled with #e oz4 per square yard and cleaned with ,types ,a and ,c renovators4 ,this test indicated that a nearer approach to the results in cleaning dirty carpets was possible with this substance than with any which the author had tried4 ,the author repeated ,mr4 ,miller's test1 using a ,type ,f renovator1 #aj-;in4 -in4 cleaning slot1 and also a ,type ,f renovator1 #ae-;in4 -in4 to -in4 cleaning slot4 ,in duplicating these tests the author was associated with ,mr4 ,e4 ,l4 ,wilson1 a graduate of the ,institute1 who was familiar with the methods used by ,mr4 ,miller4 ,with his assistance1 the conditions of ,mr4 ,miller's tests were almost exactly duplicated4 ,the results of ,mr4 ,miller's and the author's tests are given in the table opposite1 correction being made in the time of cleaning proportional to the size of carpets used1 to allow the same time for cleaning #a sq4 yd4 of carpet by each renovator4 ,,table #b4 ,,cleaning ,,tests ,,of ,,carpets ,,filled ,,with #e ,,oz4 ,,of ,,quicksand ,,per ,,square ,,yard ,,of ,,carpet4 ---------------------------------------- ----------------------- ,type of ,renovator4 ,a ,c ,f ,f ---------------------------------------- ----------------------- ,vacuum in renovator1 in4 hg4 #d #d #c #c ,air exhausted1 cubic feet per minute #bg #dd #ei #ed ,material removed1 per cent4 of total1 #a min4 #fj #ec #ff #ec ,material removed1 per cent4 of total1 #b min4 #ge #fe #hc #ge ,material removed1 per cent4 of total1 #c min4 #hb #gd #id #hf ,material removed1 per cent4 of total1 #d min4 #hg #hb #ajj #id ,material removed1 per cent4 of total1 #e min4 #ib #hg -- #ajj ,material removed1 per cent4 of total1 #f min4 #ie #ic -- -- ,h4 ,p4 per ounce sand #j4jij4achj4jhdj4aji ,ounces sand per minute #c4b #c4a #e4c #d4j ---------------------------------------- ----------------------- ,the results of these tests are shown graphically in ,fig4 #ah4 ,comparison of these curves with the curves of cleaning dirty carpets 7,fig4 #ag71 shows a falling off in the efficiency of cleaning by ,type ,a renovator while there is a gain in the efficiency in cleaning by all of the other types of renovators1 ,type ,c being now nearly as efficient as ,type ,a1 while ,types ,f and ,f renovators are now more efficient than ,type ,a4 ,this result must be due either to the increased quantity of material to be removed1 #e oz4 per square yard in case of the sand as against #b oz4 per square yard in case of the dirt1 or else to the change in the character of the material removed1 the sand having much sharper surfaces than would be encountered in case of dirt which must necessarily be ground under the feet before it reaches the carpet1 or to the longer nap of the carpet4 ,illustration3 ,,fig4 #ah4 ,,cleaning ,,tests ,,of ,,carpets ,,filled ,,with ,,quicksand4 ,in order to determine the effect of the increase in the quantity of material on the results1 the tests were repeated using #a oz4 of sand per square yard of carpet in each case1 omitting the test on ,type ,f renovator4 ,these tests were made on a glue-sized back1 short napped ,brussels carpet1 using as much sand as could readily be worked out of sight in this carpet4 ,the results of tests are given in the following table3 ,,table #c4 ,,cleaning ,,tests ,,using #a ,,ounce ,,of ,,sand ,,per ,,square ,,yard ,,of ,,carpet4 ---------------------------------------- ------------------------- ,type of ,renovator4 ,a ,c ,f ---------------------------------------- ------------------------- ,vacuum in renovator1 in4 hg4 #b #d #a #b #d #c ,air exhausted1 cubic feet per min4 #af #bg #bd #cg #dd #ei ,material removed1 per cent4 of total1 #a min4 #dh #ed #de #dh #ej #ej ,material removed1 per cent4 of total1 #b min4 #gj #hg #fj #fc #fe #gc ,material removed1 per cent4 of total1 #c min4 #ia #ajj #gc #ge #gg #hg ,material removed1 per cent4 of total1 #d min4 #ajj -- #gf #ha #hh #ajj ,material removed1 per cent4 of total1 #e min4 -- -- -- #hh #ig -- ,material removed1 per cent4 of total1 #f min4 -- -- -- #ib #ajb -- ,h4 ,p4 per ounce sand #j4jdg #j4adcj4jf #j4aie #j4ddj4bbc ,ounces sand per minute #a4e #b4j -- #j4ib #a4jbb4aa ---------------------------------------- ------------------------- ,the results of these tests at the higher vacua are shown graphically in ,fig4 #ai4 ,comparison of these curves with those obtained when removing sand from a long napped carpet 7,fig4 #ah71 shows3 ,first1 a marked increase in the efficiency of ,type ,a renovator1 this being slightly better than obtained when cleaning a dirty carpet4 ,second1 practically no change in the efficiency of ,type ,c renovator4 ,third1 a small decrease in the efficiency of ,type ,f renovator1 which still shows a much higher efficiency than when cleaning dirty carpets4 ,in order to determine how much1 if any1 of these changes in the behavior of the renovators was due to the increase in the quantity of material to be removed1 the horizontal line1 representing #a oz4 of sand remaining in the long-napped carpet1 was drawn on ,fig4 #ah and1 using this as a base line1 it will be seen that ,type ,a renovator removes this remaining material in three minutes1 the same time as was required to remove the same amount from the short-napped carpet4 ,however1 the first #d oz4 of sand have been removed from the long-napped carpet in three minutes1 or at a rate #d times as fast as the last #a oz4 was removed4 ,this indicates that the narrow slot renovator is capable of handling more material than is likely to be encountered in any dirty carpet and that the apparent decrease in the efficiency of this renovator is not due to the increased quantity of material to be removed4 ,illustration3 ,,fig4 #ai4 ,,cleaning ,,tests ,,using #a ,,oz4 ,,of ,,sand ,,per ,,square ,,yard ,,of ,,carpet4 ,it will be noted that the ,type ,c renovator removed the last #a oz4 per square yard from the long-napped carpet in the same time that was required by ,type ,a renovator1 while it needed nearly twice as long to remove this amount of material from the short-napped carpet 7,fig4 #ai74 ,this renovator1 however1 was slower in removing the first #d oz4 per square yard4 ,type ,f renovator removed the last #a oz4 per square yard from the long-napped carpet in two minutes1 while it required twice this time to remove the same amount from the short-napped carpet4 ,this renovator also removed the first #d oz4 per square yard from the long-napped carpet in two minutes1 while it required three minutes for ,type ,a and #c- minutes for ,type ,c renovators to remove the same quantity4 ,it is1 therefore1 evident that sand is removed more rapidly from a long than from a short-napped carpet when a wide slot renovator is used4 ,the same time is required to remove small quantities of sand from a long or short-napped carpet with a narrow slot4 ,this phenomenon is probably due to the sand being held in the carpets by the adhesion of its sharp edges to the sides of the nap1 this being more pronounced in the case of the long-napped carpet where it is easier to work the material out of sight without grinding it into intimate contact with the pile of the carpet4 ,when the wide-slot renovator passes over the carpet1 the carpet is arched up into the slot and the upper ends of the nap separated4 ,the longer the nap or the wider the slot1 the greater will be this separation4 ,with the long-napped carpet this separation will at once release the sand1 while1 in case of the short nap1 there is less separation and also more adhesion of the sand to the pile of the carpet1 due to the harder grinding necessary to work the material out of sight4 ,therefore1 the wider the cleaning slot used1 the faster the sand will be removed1 as is evident by comparison of the tests of ,types ,f and ,f renovators on the long-napped carpet4 ,with the narrow slot renovator the arching of the carpet under the cleaning slot is negligible and no advantage is gained when using this type of renovator to remove sand from a long-napped carpet4 ,it is also possible that the nap of the carpet may be longer than the width of the cleaning slot1 in which case the nap will not snap back to a vertical position when it is under the cleaning slot1 but will be pressed down and will impair the action of the renovator4 ,the author considers that the width of the slot should always be greater than the length of the nap of the carpet in order to do effective cleaning4 ,shortly after making the above-described tests1 the author had occasion to make somewhat similar tests1 using a sand-filled carpet1 in an attempt to try out a proposed carpet cleaning test intended to be used as a standard for use in specifications for a vacuum cleaning system4 ,when a ,wilton carpet was used1 it was found that neither ,type ,a or ,c renovator would fulfill the test requirements1 which were within the results obtained in tests already described4 ,unfortunately a ,type ,f renovator was not available1 but the author is of the opinion that it would have done better4 ,the test was then repeated1 using a ,brussels carpet and the test requirement was easily met4 ,this discovery led the author to make further tests of carpets of different makes1 filled with sand and cleaned under the same conditions which yielded far from uniform or satisfactory results1 and the use of a cleaning test1 where artificially-soiled carpets are used1 was abandoned4 ,the author is of the opinion that no substance artificially applied to a carpet1 other than regular sweepings1 will give anything like the same results as will be obtained in actual cleaning4 ,sand seems to be the only substance which can be worked into the carpet that is nearly as difficult to remove as the actual dirt found in carpets1 and1 in many cases1 this material gives results that are misleading and unfair to some types of renovators4 ,no test which uses a carpet artificially soiled with artificially prepared dirt is considered to be of any value in determining the relative efficiency of various types of carpet renovators4 ,a series of tests was made by ,mr4 ,sidney ,a4 ,reeve consulting engineer1 of ,new ,york ,city1 in ,october1 #aiaj1 at the works of the ,vacuum ,cleaner ,company1 ,plainfield1 ,n4 ,j41 in which the conditions were such as would give much more uniform results than were possible in the tests made by the author4 ,in making these tests the renovator was held firmly clamped in any desired position in a wooden carriage rolling upon a straight wooden track4 ,the portion of the carriage supporting the sweeper is attached to the remainder of the carriage by hinges1 so that the sweeper is free to seek its own contact with the carpet4 ,the carriage was given a reciprocating motion by its attachment to a large bell crank1 which in turn received its motion from the factory shafting4 ,the construction of the bell crank was such that the driving power could be readily thrown in and out of gear at any time4 ,the carpet was stretched tightly upon a platen which was fitted for movement across the line of motion of the sweeper1 along straight guides suitably attached to the floor4 ,the ends of the carpet were first wedged tightly in clamps and the clamps wedged apart so as to stretch the carpet4 ,the tests consisted in first weighing the carpet1 then stretching it upon the platen1 then sprinkling thereon a suitable and known weight of dirt taken from the separators of the company's machines1 from which the lint and coarse1 fibrous material had been sifted and which was thoroughly trodden into the fibres of the carpet1 whereupon the sweeper was set in motion for a given number of strokes4 ,in nearly all cases the tests were repeated upon the same piece of carpet1 with the same charge of dirt1 by repeatedly placing the carpet in the frame and giving it a further and more extended cleaning4 ,all tests were corroborated by repetition before being admitted to the records4 ,every effort was made to have the tests approach the conditions occurring in actual practice1 as nearly as possible1 and still keep them definite and measurable4 ,the carpet used was a ,wilton1 of the standard width of #bg in4 and something over a yard long1 and the sweeper was given a stroke of #cd in4 at the rate of #dj strokes per minute4 ,the sweepers were attached to a #f-;ft4 tubular handle1 -in4 inside diameter1 and connected to the separator by #ej ft4 of #a-;in4 diameter hose4 ,before making any tests1 the piston pump used in the experiments was calibrated by pumping through a rotary meter and the amount of air moved per revolution for each degree of vacuum from open inlet to closed system was carefully determined4 ,in making the tests of various renovators1 each renovator was allowed to pass the same amount of air as the others tested in comparison therewith and the vacuum at the renovator and at the separator was allowed to be what was necessary to pass this known amount of air through the renovators4 ,this method is widely different from that used by the author where the degree of vacuum at the renovator head was determined and used as a limiting factor1 the quantity of air being allowed to vary as necessary to produce this vacuum4 ,the results of three series of tests are given in ,fig4 #bj1 which shows those obtained with ,kenney ,type ,a renovators1 having a face #ab in4 in4 and a cleaning slot #aa in4 in4 ,curve ,a was made with the angle of the handle such as would give as near as possible a perfect contact of the sweeper with the carpet4 ,curve ,b was made with the sweeper handle canted #e below the proper angle4 ,curve ,c was made with the sweeper handle raised approximately #ae above the proper angle4 ,the ordinates represented the amount of dust in the carpet in #djths of a pound1 also reduced by the author to ounces1 and the abscissae the number of strokes made by the sweeper4 ,illustration3 ,,fig4 #bj4 ,,three ,,series ,,of ,,tests ,,with ,,kenney ,,type ,a ,,renovators4 ,curves ,b and ,c show the loss in efficiency which occurs when the renovator is canted from its proper position on the carpet4 ,this falling off in efficiency will necessarily be greater the wider the face of the renovator1 as is shown in further tests by ,mr4 ,reeve1 using a ,type ,c renovator1 which tests also show that this renovator gives a slightly higher efficiency when operated with the inrush slot stopped1 as is shown in ,fig4 #ba4 ,in this curve the ordinates represent the per cent4 of normal dirt1 i4 e41 the amount likely to be found in a dirty carpet1 remaining in the carpet at any stage of the cleaning1 and the abscissae the number of strokes that have been made by the sweeper4 ,heavy solid lines represent the results with the inrush open and dotted lines the results with the inrush stopped4 ,the figures on the curve represent the degree to which the handle has been varied from the position giving the best results in cleaning4 ,illustration3 ,,fig4 #ba4 ,,tests ,,by ,,mr4 ,,reeve1 ,,using ,,type ,c ,,renovator4 ,fig4 #bb shows the results of tests by ,mr4 ,reeve using a renovator of ,type ,d1 having a double cleaning slot1 and indicate that this type of cleaner is not as efficient as ,type ,a and is affected more by the canting of the handle from the best angle for cleaning4 ,the above mentioned tests are published through the courtesy of ,messrs4 ,ewing and ,ewing1 attorneys for the ,vacuum ,clean ,cleaner ,company4 ,since the method of making these tests is entirely different from that used by the author1 a comparison of the results1 with any assurance that the same conditions existed in both cases1 is impossible4 ,it occurred to the author that a comparison of the results of the tests by ,mr4 ,reeve1 using a carpet artificially filled with actual dirt taken from carpets1 with the tests made by the author on carpets naturally soiled1 would tend to show if equal results could be obtained by a vacuum cleaner by artificially soiling a carpet with dirt taken from another carpet1 and in cleaning a carpet naturally soiled4 ,illustration3 ,,fig4 #bb4 ,,tests ,,by ,,mr4 ,,reeve1 ,,using ,,type ,d ,,renovator4 ,the author has reduced these results to the same units of time per square yard of carpet cleaned as in the test on the ,philadelphia carpet with the small-sized ,type ,a renovator 7#aa-;in4 -in4 face and #aj-;in4 -in4 cleaning slot74 ,the carpet used by the author contained #f sq4 yds4 and was held in cleaning by a weight at each corner1 while the carpet used by ,mr4 ,reeve was yd4 wide and cleaned for approximately one yard of its length1 the relative size being #a to #h4 ,the time of cleaning was #f min4 in the author's test which would correspond to -min4 cleaning in ,mr4 ,reeve's test1 or #cj strokes of the sweeper4 ,the total dust in the carpet in ,mr4 ,reeve's test was lbs41 or #b4ff oz4 per square yard1 and his test is compared with the author's test with the carpet containing #b oz4 per square yard4 ,calculation of the per cent4 of total dirt removed in each #e strokes of the sweeper in ,mr4 ,reeve's test1 and a comparison of the per cent4 of dirt removed in each one minute's test by the author are given below3 ,,table #d4 ,,comparison ,,of ,,tests ,,made ,,by ,,mr4 ,,reeve ,,and ,,by ,,the ,,author4 ---------------------------------------- ------------------ ,,mr4 ,,reeve',s ,,test4 ,,author',s ,,test4 ---------------------------------------- ------------------ ,material removed1 ,material removed1 ,strokes4 per cent4 of total4,minutes4 per cent4 of total4 ---------------------------------------- ------------------ #e #fb #a #fj #aj #hj #b #ha #ae #hi #c #ij #bj #id #d #ie #be #ig #e #ih #cj #ii #f #ajj ---------------------------------------- ------------------ ,the above comparison was made using curve ,a1 ,fig4 #bj1 with the sweeper at its best angle with the floor4 ,the close agreement of the two tests indicates that a carpet artificially soiled with dirt actually removed from another carpet by a vacuum cleaner is as difficult to remove as dirt which has been worked into a carpet by ordinary daily use4 ,this condition does not result when any other substance is used to artificially soil the carpet1 as will readily be seen by reference to the tests of carpets filled with sand and other substances which have been described in this chapter4 ,a comparative test of three different renovators was recently made by the author4 ,renovator ,no4 #a had a cleaning slot #ad in4 long by in4 wide1 the edges of the slot being a segment of a circle having a -in4 radius4 ,this form of cleaning surface allows very small area of contact with the surface cleaned and permits the admission of large air volumes1 about #ef cu4 ft41 with #b-;in4 vacuum4 ,it is practically a ,type ,f renovator1 similar to that used in the tests at ,hartford4 ,renovator ,no4 #b had a cleaning slot #i in4 long and in4 wide1 the face of the renovator being approximately in4 wide and practically a plain surface1 a typical ,type ,b renovator4 ,renovator ,no4 #c had a cleaning slot #g in4 long and in4 wide1 the face of the renovator being in4 wide and the edges slightly rounded1 a typical ,type ,a renovator4 ,the carpet used was a ,colonial velvet rug with -in4 nap1 closely woven1 containing #f sq4 yds4 ,this rug was filled with #ab oz4 of dirt taken from separators of cleaning machines1 from which the lint and litter had been screened4 ,this was rubbed into the carpet until no dirt was visible on the surface1 the surface being then lightly swept with a brush and weighed4 ,in cleaning this carpet the renovator was passed once over the entire surface at the rate of about #gj ft4 per minute4 ,this required six strokes and #ej seconds for ,no4 #a cleaner1 nine strokes and #gg seconds for ,no4 #b cleaner1 and #ab strokes and #ajj seconds for ,no4 #c cleaner4 ,the carpet was then weighed1 spread down and gone over three times1 weighed1 spread down and gone over four times4 ,this operation was repeated until the carpet came within oz4 of its weight when received4 ,each of the three renovators was operated with a vacuum of #b in4 at the renovator4 ,the results of these tests are illustrated by curves #a;,a1 #b;,a and #c;,a in ,fig4 #bc4 ,this shows that to remove #ie of the dirt the renovator had to be passed over the carpet #bj times for ,no4 #a renovator1 #ae times for ,no4 #b renovator and #h times for ,no4 #c renovator4 ,similar tests were then made with each of the renovators1 with a vacuum of #d4e in4 of mercury at the renovator4 ,the results are shown by curves #a;,b1 #b;,b and #c;,b 7,fig4 #bc7 ,these show that to remove #ie of the dirt the renovator had to be passed over the carpet #aa times with ,no4 #a renovator1 #f times with ,no4 #b1 and #d times with ,no4 #c4 ,these tests are all on the same carpet1 with the same quantity of the same dirt and with the renovators moved at the same speed in each case4 ,the comparison of the results should give a fair indication of the efficiency of the different types of renovators at different degrees of vacuum within the renovator and1 therefore1 form the most conclusive proof of the statements relative to the efficiency of renovators as given in this chapter4 ,all cleaning tests that the author has observed indicate that the higher the vacuum within the renovator the more rapid and effective the cleaning1 and that the efficiency of the renovator is fully as high with a small as with a large volume of air passing through the renovator and with the same degree of vacuum within same4 ,therefore1 the most effective and economical renovator should be that which gives the highest vacuum with the least air passing4 ,illustration3 ,,fig4 #bc4 ,,tests ,,showing ,,efficiency ,,of ,,different ,,types ,,of ,,renovators ,,at ,,different ,,degrees ,,of ,,vacuum4 ,if the degree of vacuum within the renovator be carried to an abnormally high degree1 there will be a tendency for the renovator to cling so close to the carpet that its operation will be difficult and the wear on the carpet rapid4 ,the production of this high vacuum1 with a larger quantity of air exhausted1 will result in the expenditure of power at the renovator in excess of the gain in efficiency and speed of cleaning4 ,it is evident that the wider the cleaning slot1 the greater will be the tendency of the renovator to stick to the carpet with a high vacuum within the same4 ,the author has experienced no difficulty in operating the #aj-;in4 renovator1 with -in4 cleaning slot1 with a vacuum as high as #i in4 of mercury1 but wider-slot renovators always push hard when any high degree of vacuum exists within them4 ,effort ,necessary to ,operate ,various ,types of ,renovators4--,the author made a series of tests to determine the effort necessary to operate the various types of renovators under different conditions4 ,in making these tests the renovator was attached to a spring balance and pulled along the floor1 the pull required to move the renovator being observed by the reading of the balance4 ,three types of renovators were used in this test3 ,type ,a1 having a cleaning slot in4 wide and #ab in4 long2 ,type ,c1 having a cleaning slot in4 wide and #ab in4 long1 with an auxiliary inrush slot in-wide and #ab in4 long2 ,type ,f1 having a cleaning slot in4 wide and #aj in4 long4 ,the results were as follows3 ,,table #e4 ,,effort ,,necessary ,,to ,,operate ,,cleaning ,,tools4 ---------------------------------------- ------------------- ,vacuum at ,type of ,renovator1 ,pull1 ,air1 cu4 ft4 ,kind of ,carpet4 ,renovator4 ,in4 ,hg4 ,pounds4 per min4 ---------------------------------------- ------------------- ,brussels1 short ,a #h #bj #bg ,napped1 close back ,c #f #ag #ca ,f #c #aa #ei ,axminster1 long nap ,f #c #ad #ei ,velvet1 with glue ,a #h #ah #bh ,sized back ,c #f #ag #ca ,velvet1 without glue ,a #c #ae #dj ,sized back ,c #a #ab #de ,linoleum ,a #ac #bc #ab ,c #a #aj #dj ---------------------------------------- ----------------- ,it may be noted that1 when operating on the ,brussels and the glue-sized velvet1 the pull required to move all types of renovators bears a direct ratio to the degree of vacuum under the renovator1 and that the quantity of air exhausted is the same for each renovator on either carpet1 but different for each type of renovator4 ,it is evident that1 in this case1 very little air enters the renovator by passing up through the carpet1 and hence the action of the inrush slot on ,type ,c renovator is noticeable only to a slight degree4 ,when operating on velvet carpet1 without glue-sized back1 the inrush slot1 in conjunction with the greater quantity of air coming through the carpet1 has caused the passage of a large quantity of air1 while the vacuum maintained at the renovator is greatly reduced over that which was maintained under ,type ,a renovator when the same quantity of air was passing4 ,in this case1 nearly all of the air entering ,type ,a renovator came from the under side of the carpet4 ,the effect on the efficiency of cleaning with ,type ,c renovator under these conditions can readily be imagined1 by reference to former tests1 as being greatly reduced over that of ,type ,a when passing the same quantity of air4 ,with linoleum1 the action of the inrush slot of the ,type ,c renovator has again greatly reduced the vacuum under the renovator1 although the quantity of air is much in excess of that passing ,type ,a renovator4 ,the difference in the behavior of the renovators on different makes of carpet is seen to be due largely to the difference in the quantity of air which passes up through the carpet into the renovator4 ,it is evident that1 with the same degree of vacuum within the renovator1 all types are equally easy to push and that1 if the vacuum within the renovator becomes higher than is necessary to produce good cleaning results1 unnecessary effort will be required to operate the renovator4 ,relative ,damage to ,carpets with ,various ,types of ,renovators4--,a few tests have been made by the author to determine the relative damage to carpets with the various types of renovators in use and it is found that1 when the edges of the renovators are made exceedingly sharp1 considerable nap is pulled out4 ,however1 if the edges are made slightly rounding and not too narrow1 no undue wear will occur with any of the types of renovators described1 provided the vacuum in the renovator is not permitted to become greater than #e in4 of mercury4 ,the author considers that for best results the vacuum should not be less than #c in4 of mercury at the renovator and that at least #b in4 is necessary to do even fair work1 while1 to permit easy operation and prevent undue wear on the carpets1 it should not be higher than #e in4 ,before deciding which type of renovator will be most economical to use in any case the character of the cleaning to be done must be considered4 ,of the various types of renovators considered in this chapter1 ,type ,c can be dismissed at once1 as it is neither as effective a dust remover as ,types ,a or ,f nor will it remove litter any more effectively than ,type ,f4 ,tests of ,type ,d renovator do not show as good results as a dust remover as ,type ,a1 nor will it remove litter any more effectively4 ,type ,e renovator is a modification of ,type ,c and is not likely to be any better4 ,the selection1 therefore1 lies between ,type ,a and ,type ,f renovators1 the former being by far the best dust remover1 while the latter will pick up a limited amount of small litter1 such as matches1 cigar and cigarette stumps1 and small bits of paper4 ,where large quantities of these articles are likely to be encountered1 it is more important that the renovator should be capable of picking them up1 but1 unfortunately1 when these articles are met with1 there are also likely to be much larger articles present that cannot be picked up by any but a specially-designed renovator1 and other means must be employed to remove them4 ,in residences1 private offices and nearly every place where carpets or rugs are likely to be used1 waste baskets and cuspidors are provided and the articles mentioned are deposited in them rather than on the floor4 ,thus1 the renovator will be required to remove dust1 cigar ashes and sand or mud only1 all of which can be readily removed with a ,type ,a renovator with less expenditure of power than with a ,type ,f renovator4 ,public places1 such as ante-rooms1 reception rooms and other offices to which the general public is admitted in great numbers and which are sometimes carpeted1 are likely to contain articles which can be picked up by ,type ,f renovator and not by ,type ,a4 ,for cleaning such places1 a ,type ,f renovator is necessary1 although it requires considerably more power1 but the author sees no reason why this type of renovator should be used to the exclusion of ,type ,a1 even in buildings containing rooms of this character4 ,if the building also contains several rooms where litter will not be encountered1 the author would recommend that both types of renovators be used1 each in its proper place1 and thereby cause a considerable saving of power in cleaning rooms where no litter is encountered4 ,for residence work there is little need of providing carpet renovators capable of picking up litter and1 also1 there will be very little bare floor cleaning to be done1 which requires larger volumes of air4 ,a smaller capacity exhausting plant1 therefore1 can be installed1 if the ,type ,a renovator is adopted4 ,in large office buildings where all cleaning is done after office hours1 where the building is provided with its own power plant1 and where speed of cleaning and ability to clean all apartments with the fewest tools to be carried by the cleaners is desired1 it appears to be better to use only ,type ,f renovators for all carpet work1 as the extra power required will not be of vital importance4 ,summing up the matter1 the author believes that both ,type ,a and ,f renovators have their uses in their proper places but that ,type ,a has the widest field of usefulness1 yet it need not invade the field of the other4 ,he also believes that this fact will be realized by manufacturers in the near future1 when the two types of renovators will work together side by side for the general good of the manufacturers and the users4 ,,chapter ,,iv4 ,,other ,,renovators4 ,the renovator which is next in importance to the carpet renovator is that used for cleaning bare floors4 ,the earliest form of this renovator was the oscillating floor type introduced by ,mr4 ,kenney4 ,this was a modification of the narrow-slot carpet renovator introduced by him4 ,the body of same was curved and supported on two small wheels or rollers1 with the intention of bringing the cleaning slot close to the surface cleaned without its touching same1 as indicated in ,fig4 #bd4 ,illustration3 ,,fig4 #bd4 ,,early ,,type ,,of ,,bare ,,floor ,,renovator4 ,illustration3 ,,fig4 #be4 ,,later ,,type ,,of ,,bare ,,floor ,,renovator4 ,this form of renovator was found to be impracticable for the reason that any change in the angle with which the stem or tube connecting the body of the renovator with the handle in relation to the surface cleaned tended to make its action ineffective4 ,if the angle were made less the distance between the cleaning slot and the floor was increased1 allowing the air to enter the cleaning slot without coming in contact with the surface to be cleaned1 or1 if the angle were made greater1 it would cause the face of the renovator to strike and damage the surface of the floor4 ,the wheels or rollers on which this renovator was mounted1 being so small1 were subject to rapid wear both on their faces and in their bearings1 and when these wheels were slightly worn the renovator was practically useless4 ,on account of the above defects this form of renovator was abandoned shortly after its introduction4 ,the next form of renovator to be tried was a modification of the ordinary soft bristle brush1 such as had been in general use for cleaning hard wood floors4 ,the bristles were arranged around the edges of the cleaning slot1 in the body1 which was shaped similar to the slot in the carpet renovator4 ,rubber or leather curtains or skirting1 extending nearly to the ends of the bristles1 was placed inside of these bristles in order to cause the air in entering the body of the renovator to come into intimate contact with the surface to be cleaned4 ,the general form of this type is shown in ,fig4 #be4 ,illustration3 ,,fig4 #bf4 ,,another ,,type ,,of ,,bare ,,floor ,,renovator4 ,this form of renovator1 while more efficient than the oscillating floor type1 still had its faults in that it had a tendency to push the dirt along the floor in front of it1 much the same as the floor brush from which it was copied was designed to do4 ,also1 there was too much tendency for the air to pass into the body of the renovator without coming into intimate contact with the surface to be cleaned4 ,while this type of floor renovator or a slight modification thereof is still in use by several manufacturers today1 it never has and never will be an effective bare floor cleaner4 ,a modification of this type of bare floor renovator1 in which the bristles have been shortened and made thicker1 the skirting or flaps placed on the outside and the stem provided with a swivel joint1 is shown in ,fig4 #bf4 ,such an arrangement is an improvement over the former type as1 owing to its wider and shorter mass of bristles1 there is less tendency for the air to pass into the body of the renovator without coming into intimate contact with the surface cleaned4 ,it is still prone to push its dirt before it and is far from being a perfect bare floor cleaner4 ,illustration3 ,,fig4 #bg4 ,,bare ,,floor ,,renovator ,,with ,,felt ,,cleaning ,,surface4 ,the next modification in the bare floor renovator was the abandoning of the bristle brush in favor of a cleaning surface composed of felt as shown in ,fig4 #bg4 ,in this form of renovator the air entering the body of the same must pass either between the felt and the surface cleaned or through the felt itself1 and this air quantity is small4 ,since this renovator has a wider cleaning slot than the ,type ,a carpet renovator1 and1 as it is used with the same vacuum producer1 hose and pipe lines1 a considerable degree of vacuum will be produced under same1 especially when operated on polished floors1 where the conditions are nearly the same as we observed with ,type ,a carpet renovator operated on linoleum4 ,with the wider slot1 the effort to move these renovators becomes too great for easy operation4 ,this trouble can be overcome by using a soft grade of felt which permits sufficient air to pass through its open pores to reduce the vacuum under same and permit easy operation4 ,unfortunately1 this felt is subject to rapid wear when operated on surfaces as hard as floors and its use has been abandoned in favor of a harder felt4 ,openings are left in the felt to permit the passage of sufficient air to reduce the vacuum in the renovator to working limits4 ,these slots have taken many forms4 ,in one form the felt was placed in alternate ,x and diamond shapes1 glued to the face with small open spaces between them1 as illustrated in ,fig4 #bh4 ,however1 as these small pieces must be held in place by glue1 they are easily broken loose and the efficiency of the renovator impaired4 ,illustration3 ,,fig4 #bh4 ,,bare ,,floor ,,renovator ,,with ,,unusual ,,form ,,of ,,slot4 ,another method1 which has now become standard1 is to open the ends of the renovator sufficiently to permit easy operation4 ,this method produces high velocities at these end openings which are very effective in cleaning close to walls and in corners1 where large quantities of dust always lodge and are removed with difficulty without these open slots4 ,the wear on these felt faced renovators was found to be so rapid that hard felt or composition rubber strips1 placed so that the wear comes on the edges of the same1 have been substituted4 ,the felt or rubber was screwed on to the outside of a metal shell and projected sufficiently below the face of the metal to permit considerable wearing off of same before the surface of the metal came in contact with the surface cleaned4 ,when this occurs1 the felt strips can readily be replaced with new ones4 ,the ends are left open about in4 to form an inrush for the entering air4 ,such a type is shown in ,fig4 #bi4 ,illustration3 ,,fig4 #bi4 ,,bare ,,floor ,,renovator ,,with ,,hard ,,felt ,,or ,,composition ,,rubber ,,strips4 ,this renovator1 in either of the above-described forms1 is a great improvement over the bristle brush in that the air passing into the body of the renovator must come into intimate contact with the surfaces cleaned1 but it still has the disadvantage of tending to push the dirt before it4 ,a modification of the above-described renovators has been introduced1 in which the wearing surface of the renovator1 which is covered with felt1 is rounded as shown in ,fig4 #cj4 ,with this form of bare floor renovator1 the air passing into same is not only brought into intimate contact with the surface cleaned but the dust is also crowded under the curved surface of the renovator as the same is pushed over the floor and thus brought directly into the path of the air current4 ,illustration3 ,,fig4 #cj4 ,,bare ,,floor ,,renovator ,,with ,,rounded ,,wearing ,,surface4 ,the last named type is by far the most effective for cleaning either polished or unpolished floors4 ,it must be provided1 however1 with inrush slots in order to prevent its sticking and preventing easy operation4 ,when operated with hose pipe and a vacuum producer necessary to produce #b in4 of vacuum in ,type ,a carpet renovators1 at least #cj cu4 ft4 of air must be permitted to pass the renovator4 ,when operated with systems adapted to produce #d in4 of vacuum in ,type ,a carpet renovators1 at least #gj cu4 ft4 of air must pass the renovator in order to permit easy operation4 ,this increase in the air quantity without change in the degree of vacuum in the case of these renovators1 is not without increase in efficiency1 as in the case of the carpet renovators1 because large quantities of dust and also small litter are met with much more frequently on bare floors than on carpets4 ,with the increase in the volume of air passing1 it is possible to pick up much heavier articles than with the smaller quantity4 ,it is also possible to pull dust out of deep cracks or from surfaces which are not in contact with the renovator face1 such as the spaces between the slats of floors of trolley cars4 ,this would not be possible with the small air quantity4 ,the use of the larger quantity of air prohibits the use of small-sized hose and pipe and1 therefore1 larger articles can be conveyed through them4 ,where a large amount of bare floor must be rapidly cleaned the use of the larger air quantity is recommended4 ,illustration3 ,,fig4 #cj;a4 ,,the ,,tuec ,,school ,,tool4 ,a renovator 7,fig4 #cj;a7 of unusual interest has recently been developed by ,the ,united ,electric ,company1 known as the ,tuec school tool4 ,this is a bare floor tool open at both ends4 ,it is made telescopic and is mounted on three wheels fitted with spring-actuated guide rails which are adjustable to the exact distance between the legs of school desks4 ,a turbine motor1 operated by the air passing through the renovator1 is arranged to drive two of the wheels by means of worm gear and clutch4 ,in operation the tool is placed opposite the front of a row of desks4 ,the clutch engaged on the turbine propels the tool through the space between the desk legs to the rear of the room4 ,when the tool strikes the wall at the rear of the room1 the clutch is disengaged and it is pulled back by drawing in the hose4 ,the spring-actuated guides cause the cleaning slot to lengthen when passing between the desk legs thereby cleaning these spaces4 ,the tool is then sent up the aisle1 the wheels being set so that it hugs the left side of the aisle when going up and the right side when pulled back4 ,the use of this form of tool should result in considerable saving of time in cleaning school rooms4 ,unfortunately1 it cannot be operated where pedestal stools are used4 ,for use in cleaning walls1 ceilings1 and other flat surfaces of similar character1 the bristle brush is practically the only form of renovator used4 ,rubber skirting cannot be used on these brushes as it is too harsh for the easily-marred surfaces encountered by this renovator1 and cotton flannel or a very soft grade of felt takes the place thereof4 ,this change in the material used for skirting results in a greater short-circuiting of the air into the cleaner without coming into intimate contact with the surface cleaned than occurs when used with rubber or hard felt on bare floors4 ,as the material to be removed from surfaces of this character is very light dust1 which has simply settled on the surface and is not ground in1 it is very easy to dislodge4 ,when a bristle brush1 with a small volume of air passing through same1 is used to remove this material1 a greater portion thereof is pushed off the projections and other points of lodgment and falls to the floor from whence it must be removed by a second operation1 using a floor renovator4 ,in fact1 the use of an ordinary bristle brush1 followed by the use of a floor renovator1 will give almost as good results as the use of a bristle wall brush with a small quantity of air passing4 ,however1 with a large quantity of air passing into the renovator1 this light surface dust will all be picked up by the rapidly-moving air current and effective cleaning can be accomplished without the renovator coming into direct contact with the surface to be cleaned4 ,the author considers that a different form of renovator is necessary to effectively clean walls1 ceilings and similar flat surfaces1 with a small quantity of air passing and would recommend the use of some form of renovator having a cleaning face composed of cotton flannel or some other soft substance which could be moved over the surface cleaned1 in intimate contact therewith and without damage thereto4 ,with the soft1 open fibre of the substance necessary to be used as a working surface1 sufficient air would enter the renovator without resorting to the use of inrush slots or openings and much better results would be obtained4 ,no such renovator has been designed for this purpose to date1 for what reason the author does not know1 and until some such renovator is produced a large volume of air will be necessary for cleaning this kind of surfaces4 ,illustration3 ,,fig4 #ca4 ,,round ,,bristle ,,brush ,,for ,,carved ,,or ,,other ,,relief ,,work4 ,an illustration of this defect in the wall brush was brought to the author's attention recently in watching a gang of laborers cleaning the walls in the ,u4 ,s4 ,treasury ,building4 ,they had at their disposal a portable cleaner of the most efficient type1 but in lieu of using the wall brush provided with same1 they were rubbing off the walls with a cloth mop which had been soaked in oil1 then air-dried1 known as the 8dustless duster40 ,this was mounted on the end of a pole4 ,the workmen frequently cleaned this duster with the vacuum cleaner hose without any renovator attached thereto4 ,this cleaner1 with brush in use1 passed approximately #cj cu4 ft4 of free air per minute4 ,it is evident that these laborers had learned by experience that it was practically useless to try to remove dust from the walls by the direct application of the wall brush to surfaces and were undoubtedly accomplishing much better results in the roundabout way they had of necessity adopted4 ,when carved or other relief work is encountered1 the round bristle brush1 with extra long bristles and cotton flannel skirting1 is nearly universally used4 ,this type of renovator is shown in ,fig4 #ca4 ,owing to the irregularity of such surfaces1 intimate contact therewith cannot be obtained and practically no results will be had unless there is a large quantity of air passing through the renovator4 ,when a large quantity of air is available1 nearly as good results in cleaning this character of surface can be obtained by the use of the straight rubber-tipped corner cleaner1 with a round opening about in4 in diameter1 as illustrated in ,fig4 #cb4 ,a very high velocity will be obtained through this renovator which will pull the dust out of inaccessible places4 ,this form of cleaner is also very effective for cleaning the corners of rooms1 where the floor and walls intersect1 veritable dust catchers that they are1 the cleaning of which is fully as important as it is difficult4 ,pigeon holes and other small compartments in safes1 desks and similar furniture can be easily cleaned with this little renovator by simply introducing it into the front of such compartment4 ,illustration3 ,,fig4 #cb4 ,,rubber-,,tipped ,,corner ,,cleaner ,,for ,,use ,,on ,,carved ,,or ,,other ,,relief ,,work4 ,illustration3 ,,fig4 #cc4 ,,early ,,type ,,of ,,upholstery ,,renovator4 ,to be effective1 this renovator must pass approximately #ee cu4 ft4 of air per minute and will require a vacuum within the renovator of approximately #c in4 of mercury4 ,where only a small quantity of air is available1 the author considers that it is better to make use of compressed air to blow the dust out of relief work1 pigeon holes1 and other inaccessible places and subsequently pick this dust up with other forms of renovators after it has found lodgment at more accessible points4 ,the cleaner which has met with the most disastrous results to the surfaces cleaned is the furniture or upholstery renovator4 ,this has nearly always taken the form of a small carpet renovator4 ,the type of upholstery renovator used for many years by the ,sanitary ,devices ,manufacturing ,company is illustrated in ,fig4 #cc4 ,this renovator had an inrush slot in the center1 separated from a cleaning slot on each side by a partition extending to within in4 of the working face of the renovator4 ,it had the hose connected into one end which was extended to form a handle4 ,with this cleaning tool it was considered impossible to obtain a high vacuum within the renovator1 as the inrush slots were supposed to act as vacuum breakers4 ,however1 as the surface of the upholstery is not firmly attached to the furniture it could be drawn up into the cleaner1 closing the space under the partitions and permitting a high vacuum to be obtained4 ,this caused the renovator to stick1 but1 owing to the narrow slot on each side of the inrush1 the fabric was not caught4 ,other manufacturers used a renovator with a single slot1 in some cases as wide as in41 and instances are on record where the coverings of the furniture have been drawn up through the cleaning slot into the renovator and wedged so tightly that it was necessary to cut the covering from the furniture in order to release the renovator4 ,to overcome this difficulty one manufacturer constructed the renovator in two pieces1 secured together with screws1 so that1 in case the renovator became caught1 it could be taken apart to release the fabric4 ,many manufacturers have attempted to overcome this destructive tendency of the straight-slot upholstery renovator by inserting partitions on the cleaning face of the renovator1 thus dividing the cleaning slot into a number of small slots the area of each not being sufficiently large to permit the drawing in of the fabric4 ,these cleaners have followed two general forms1 one having narrow slots running lengthwise of the cleaner1 as illustrated in ,fig4 #cd4 ,this form reduces the destructive tendency to a great extent1 but does not entirely prevent drawing the fabric into the renovator4 ,if the partitions across the renovator be continuous1 as indicated by the sketch1 there will be a portion of the renovator which will not do any cleaning4 ,another form uses short slots1 sufficiently inclined for the top of one slot to overlap the bottom of its neighbor1 as shown in ,fig4 #ce4 ,this form of renovator is effective throughout its entire length and the small area of each slot makes it practically impossible to draw the fabric into the cleaning slot4 ,it is considered by the author to be superior to the former type1 especially when cleaning lace curtains or silk hangings or any other very light fabric4 ,illustration3 ,,fig4 #cd4 ,,upholstery ,,renovator ,,with ,,narrow ,,slots ,,to ,,prevent ,,damage ,,to ,,furniture4 ,however1 if the exhauster be of such characteristics and the hose and pipe lines be so proportioned that there is practically a constant vacuum in the renovator1 regardless of the quantity of air passing1 and provided this vacuum is not allowed to exceed #e or #f in4 of mercury1 no disastrous effects will be experienced in cleaning light-weight fabrics with a straight-slot renovator having a cleaning slot not over in4 wide4 ,the use of this type1 in connection with a system having the above-described characteristics1 is recommended whenever rapid cleaning is desired4 ,upholstery renovators make the most serviceable clothing cleaners1 while a small type of bristle brush1 not over #d in4 long and not over in4 wide1 makes the most serviceable hat brush4 ,illustration3 ,,fig4 #ce4 ,,another ,,type ,,of ,,upholstery ,,renovator ,,with ,,short ,,slots4 ,an important form of renovator is that used for cleaning between the sections and behind heating radiators4 ,a piece of tubing1 flattened at its outer end1 is by far the most effective device for this purpose4 ,this renovator1 in connection with the hat brush tool1 makes the two best renovators for use in the library1 effective cleaning being possible with not more than #bj cu4 ft4 of air per minute1 but much faster work can be done with larger quantities4 ,illustration3 ,,fig4 #cf4 ,,hand ,,brush ,,type ,,of ,,renovator4 ,another form of renovator sometimes furnished is the small hand brush4 ,this is a bristle brush1 approximately #h in4 long and #b in4 wide1 with the hose connection made into one end of same1 as illustrated in ,fig4 #cf4 ,this renovator is useful for cleaning wooden furniture1 shelves1 tables1 and other horizontal surfaces at about hand height1 but1 owing to the tendency of the air to short circuit in its way to the body of the renovator1 it will not do effective work with small quantities of air4 ,many manufacturers have produced a special renovator for cleaning stairs4 ,this has nearly always taken the form of a bristle brush1 approximately #d in4 square4 ,when renovators are rigidly attached to their stems1 this form of renovator is convenient and almost a necessity4 ,however1 when swivel joints are provided1 the ordinary carpet or bare floor renovators are fully as convenient1 and1 being larger1 are more rapid cleaners1 and the stair renovator is unnecessary4 ,in isolated cases1 where unusual cleaning is necessary1 such as the removal of cork dust from the floors of a cork factory1 picking up telegraph forms from the floors of stock exchanges1 picking up wrapping papers in watch factories1 etc41 special forms of renovators1 with large openings and large capacities for air exhaustion1 become necessary4 ,these appliances have generally taken the form similar to the carpet renovator1 but with much wider slots1 the forward edges of which are raised slightly above the surface of the floor when the renovator is in operation4 ,these renovators1 being of no use for any other purpose than that for which they are specially designed1 and requiring quantities of air in excess of those usually provided for ordinary types of renovators1 may be considered simply as special appliances and do not form a part of the outfit required to be furnished with an ordinary cleaning system4 ,another class of cleaning which requires a special system and special appliances is the renovation of furs4 ,furs must never be brushed1 as it tends to mat the hair and produce an effect opposite to renovation4 ,the only agent suitable for renovating furs is compressed air and the form of renovator best suited for this work is a straight nozzle1 flattened at the end with a slot approximately #d in4 long and not over in4 wide1 from which the air escapes in a thin sheet4 ,when held at such an angle that the air will impinge on the skin under the hair1 a thorough renovation of the fur is possible4 ,for the renovation of pillows a hollow needle1 with small openings along its sides1 supplied with compressed air1 produces the best results4 ,the needle is thrust through the cover into the mass of feathers1 the air tending to loosen up the matted feathers and to leave them in practically the same condition as when the pillow was first filled4 ,as the arrangement of the air removal system1 to permit it being reversed from exhaustion to compression1 complicates the outfit and adds to its first cost1 and as cleaning of this character is required only at rare intervals1 these renovators may also be considered as special and need not be included in the average equipment4 ,the author considers that the renovator equipment for a system in which from #bj to #cj cu4 ft4 of air per minute is exhausted for each renovator in operation1 and which the author classes as a 8small volume0 system1 should contain the following renovators in each 8set0 furnished3 ,one carpet renovator with cleaning slot in4 by #ab in4 long4 ,one bare floor renovator #ab in4 long1 with curved felt-covered face4 ,one wall renovator #ab in4 long1 with cotton flannel and curved face4 ,one upholstery renovator with slot in4 by #d in4 ,one corner cleaner4 ,one radiator cleaner4 ,in addition1 one or more hat brushes should be included with each installation4 ,the renovator equipment for a system in which #gj cu4 ft4 of air per minute is exhausted for each renovator in operation1 which the author classes as a 8large volume0 system1 should contain the following renovators in each 8set0 furnished3 ,one carpet renovator1 with slot in4 by #ae in4 ,one bare floor renovator #ae in4 long1 with curved felt-covered face4 ,one wall brush1 with skirted bristles #ab in4 long and #b in4 wide4 ,one hand brush1 with hose connection at end1 #h in4 long and #b in4 wide4 ,one #d-;in4 round brush for relief work4 ,one upholstery renovator4 ,one corner cleaner4 ,one radiator tool4 ,at least one hat brush with each system4 ,the number of sets of renovators to be furnished should naturally be at least equal to the number of sweepers which the plant will handle1 and in all buildings1 except residences1 there should be one set of renovators for each floor of the building4 ,this will be ample1 except in exceedingly large buildings4 ,the wearing face of any renovator should never be made of soft metal1 such as brass or aluminum1 as the action of the dust passing the face of the renovator1 where the velocity is always the highest in the system1 will roughen these parts and cause undue wear on the surfaces cleaned4 ,stamped steel is undoubtedly the best material for wearing surface and cast-iron ranks next4 ,these are the only materials which should be permitted4 ,,chapter ,v4 ,,stems ,,and ,,handles4 ,having discussed the various forms of renovators in detail1 the next appliance to be taken up is the connection between the renovator and the cleaning hose1 this being the next portion of the apparatus forming a conduit for the dust-laden air on its way from the renovator to the atmosphere on the exhaust side of the vacuum producer4 ,in order that the renovator may be moved about on the surfaces to be cleaned1 a rigid handle must be provided and1 in order that these various surfaces may be reached while the operator remains in a standing position1 it is necessary that this handle be of considerable1 as well as variable1 length4 ,also1 a passage for the dust-laden air must be provided in connection with this handle4 ,these conditions are best met by a metal tube1 which the author terms the stem4 ,these stems have been made of various metals1 that first used being drawn brass1 probably because it is best suited to be nickel plated4 ,on the earlier systems they were almost invariably made of ,no4 #af-;gauge tubing1 -in4 outside diameter1 and were bent at their upper end through an angle of nearly #ace in order that the hose would hang from the stem vertically downward1 when the stem was held at an angle with the floor of #de4 ,the lower ends of these stems were rigidly attached to the renovator in such a manner as to assume the above-mentioned angle with the floor when the renovator was in the proper position for cleaning4 ,in order to bring the curved portion of the stem hand high1 the stem was made approximately #e ft4 long4 ,when operated with ,type ,a carpet renovators1 these curved stems were apparently satisfactory4 ,however1 when they were used in department stores1 and other places where much bare floor cleaning was necessary1 the stems were cut through at the curved portion by the sand blast action of the dust4 ,the cutting of these stems in bare floor work1 while they were satisfactory in carpet cleaning1 indicates that the velocity in the stem1 due to the large volume of air passing the bare floor renovator1 was too great for this soft metal to withstand the impact of the dust on the curved surface4 ,with the systems in use at that time no means were provided to control the vacuum at the vacuum producer and the hose and pipe lines were small1 both of which tended to cause a wide variation in the volume of air exhausted under various conditions1 in the character of surface cleaned1 and in the number of renovators in use4 ,therefore1 the value of this destructive velocity is not readily obtainable4 ,however1 the author considers that1 in extreme cases1 the quantity of air passing through these stems may have been as high as #ee cu4 ft4 per minute4 ,as the inside diameter of the stems was in4 the area was #j4dd sq4 in41 or #j4jjcbh sq4 ft41 and the velocity through the stem was nearly #ag1jjj ft4 per minute4 ,with an average air passage of #dj cu4 ft4 per minute the velocity was #ab1bjj ft4 per minute4 ,referring to tests of carpet renovators1 ,chapter ,,iii1 it will be noted that the maximum volume of air passing through carpet renovators of ,type ,a was #cc cu4 ft4 per minute1 which gives a velocity of #aj1jjj ft4 per minute4 ,apparently1 at this velocity1 the cutting action1 due to the impact of the dust on the curved surfaces1 was not severe4 ,however1 the author considers that the maximum velocity that should be permitted through these stems is #i1jjj ft4 per minute4 ,as the dirt picked up must be lifted almost vertically1 the velocity in the stem must not become too low or dirt will lodge in the stem4 ,experiments made by the author indicate that the minimum velocity should be at least #d1jjj ft4 per minute1 in order to insure a clean stem at all times4 ,shortly after the introduction of vacuum cleaning1 the use of drawn-steel tubing for the manufacture of stems for cleaning tools was standard with one manufacturer and1 lately1 its use has become almost universal1 except in cases where very long stems are necessary1 as on wall brushes when cleaning very high ceilings4 ,for such work1 aluminum stems have been adopted4 ,this harder metal will better withstand the cutting action of the dust and can also be made much thinner and lighter in weight than brass tubing of equal strength4 ,these stems were made from #a in4 outside diameter1 ,no4 #ba gauge tubing1 having an internal area of #j4fh sq4 in41 and the author does not know of any cases where these stems have been cut by the impact of the dust4 ,stems of this metal are recommended by the author for use with all floor renovators and with wall brushes1 except in cases where exceedingly long stems are required1 when those of drawn aluminum tubing are recommended4 ,for use with ,type ,a renovators1 where the minimum air quantity is approximately #bb cu4 ft4 per minute1 the greatest area permissible is #bb ---- #djjj #j4jjee sq4 ft41 or #j4gi sq4 in41 equivalent to #a-;in4 diameter4 ,with a maximum air quantity1 under proper control1 of #ci cu4 ft4 per minute1 the minimum area will be #ci ---- #ijjj #j4jjdcc sq4 ft4 or #j4fbe sq4 in41 equivalent to #j4hi in4 diameter1 so that a #a-;in4 outside diameter stem of ,no4 #ba gauge metal1 having an inside diameter of #j4icb in41 is recommended4 ,for use with a ,type ,f renovator1 with a minimum air quantity of #dd cu4 ft4 per minute1 the maximum area of the stem will be #dd ---- #djjj #j4jaa sq4 ft41 or #a4eh sq4 in41 equivalent to #a4d in4 diameter1 while1 with a maximum air quantity of #gj cu4 ft4 per minute1 the minimum area will be #gj ---- #ijjj #j4jjgg sq4 ft41 or #a4aa sq4 in41 equivalent to #a4ah in4 diameter1 and a #a-;in4 diameter stem of ,no4 #ba gauge metal1 having an inside diameter of #a4ah in4 is recommended4 ,tests of ,mr4 ,s4 ,a4 ,reeve1 which are discussed in ,chapter ,,iii1 indicate that both edges of the cleaning slot on any renovator must be in contact with the surface cleaned in order to do effective cleaning4 ,a renovator which is rigidly connected to its stem can be effectively operated with the stem at but one angle with the surface cleaned1 which makes the cleaning under furniture1 or on wall at various heights above the floor1 impossible4 ,in order to do effective cleaning with any degree of speed and comfort to the operator1 some form of swivel joint between the renovator and its stem is necessary4 ,these swivels have been made in many forms1 one of which consists of two hemispheres connected by a bolt on their axis1 as shown in ,fig4 #cg4 ,this form of swivel is unsuited for use under these conditions1 as lint1 thread and any other small articles picked up will catch on the bolt which lies directly in the path of the dust-laden air current1 and its use should be prohibited in all cases4 ,illustration3 ,,fig4 #cg4 ,,form ,,of ,,swivel ,,joint ,,connecting ,,stem ,,to ,,renovator4 ,another form of swivel1 which is must better than the last mentioned1 is shown in the illustration of the bare floor brush1 ,fig4 #bf1 ,chapter ,,iv1 there being no obstruction in the air passage4 ,however1 these swivels are composed of moving parts which are in contact with the dust-laden air and great care must be taken in their design so that in action dust does not lodge between the wearing surfaces and shortly ruin the swivel4 ,this can be guarded against by making any opening between the parts of the swivel point away from the dust current1 as indicated in ,fig4 #ch1 in which the direction of the air current is indicated by the arrow4 ,a slightly loose fit between the wearing surfaces will permit a small leakage of air through the joint which will tend to remove any dust which may find its way into the joint4 ,however1 it is not considered advisable either to allow very much leakage through the joint1 as it reduces the net efficiency of the system1 or to depend much on the air current through the joint keeping the wearing surfaces clean4 ,the swivel indicated in the illustration of the floor brush does not entirely prevent the dust entering same and it permits the movement of the stem in a vertical plane only4 ,on the other hand1 a swivel consisting of a #de elbow1 rigidly attached to the stem and turning freely on a horizontal spud1 and fastened to the renovator1 as shown in ,fig4 #ch1 allows a motion of the stem either in a vertical plane1 which will cause the renovator to rotate1 and enable the operator to pass same around or back of legs of furniture1 or a semi-rotary motion may be imparted to the stem1 which will permit the renovator to move forward in a straight line while the angle which the stem makes with the floor will constantly decrease4 ,after a little practice the operator can place a renovator equipped with one of these swivels in almost any position without inconvenience4 ,illustrations of the possibilities of this form of swivel are presented in ,figs4 #ci and #dj1 in which an operator is shown cleaning the treads and risers of a stairway without changing her position1 and in ,fig4 #da1 where the operator is cleaning the trim of a door with apparent ease4 ,the author considers that this form of swivel is the only satisfactory joint between the renovator and its stem4 ,it is being rapidly adopted by nearly every manufacturer of vacuum cleaners4 ,illustration3 ,,fig4 #ch4 ,,swivel ,,joint ,,arranged ,,to ,,prevent ,,dust ,,lodging ,,between ,,the ,,wearing ,,surfaces4 ,in operating any renovator it is nearly always drawn backwards and forwards in front of the operator1 across the surface to be cleaned4 ,when the hose is rigidly attached to the upper end of the stem1 it becomes necessary to drag at least a portion of the cleaning hose along with the renovator when it is moved forward1 and to crowd the same back on itself when the renovator is moved backward4 ,this action has a tendency to kink or snarl the hose about itself and makes the operation of the renovator very awkward1 often causing the operator's feet to become entangled in the hose4 ,illustration3 ,,fig4 #ci4 ,,swivel ,,joint ,,in ,,use4 ,this action also brings an undue amount of wear on the hose near the end which is attached to the stem1 as may be readily noted by inspection of hose used with rigidly-attached stems4 ,this will show that the end of the hose is entirely worn through1 while the remainder of the hose is still in serviceable condition4 ,the trouble above stated can be overcome by providing a swivel joint at the point of connection between the hose and the stem4 ,a few attempts to use a joint similar to that first described in connection with the renovator and its stem1 as illustrated in ,fig4 #cg1 have been made1 but without much success1 as the bolt through the air passage catches dirt and there is not sufficient freedom of movement between the portions of the swivel4 ,variations of this form of joint have been made1 one of which is provided with a screwed union to join the two portions1 as shown in ,fig4 #db4 ,this is a much better form than that first described and has been successfully used in connection with heavy #a-;in4 diameter hose4 ,care must be exercised that the direction of the flow of air is always in the direction indicated by the arrows in the sketches1 as a reversal1 if only for a short time1 will ruin the joint1 due to lodgment of dust in the moving parts4 ,illustration3 ,,fig4 #dj4 ,,another ,,use ,,of ,,swivel ,,joint1 ,,showing ,,possibilities ,,of ,,this ,,form4 ,still another variation in this form of swivel has the two main parts made to fit one within the other and a snap ring is placed in a groove in the male portion of the joint1 this groove being deep enough to take the entire thickness of the ring4 ,the two parts are then fitted together and the ring snaps out into a corresponding groove in the female portion of the joint1 uniting the two parts4 ,this joint gives a fairly free movement to the parts thereof1 but has the disadvantage that it cannot be taken apart without breaking one of its parts4 ,illustration3 ,,fig4 #da4 ,,operator ,,cleaning ,,trim ,,of ,,door ,,with ,,swivel ,,joint4 ,illustration3 ,,fig4 #db4 ,,swivel ,,joint1 ,,with ,,screwed ,,union4 ,illustration3 ,,fig4 #dc4 ,,swivel ,,joint ,,having ,,ball ,,bearings4 ,a modification of this form of swivel has been made by the manufacturers of the last-described swivel1 in which semi-circular grooves have been cut1 one on the inside of the female portion and one on the outside of the male portion4 ,steel balls are forced into this groove1 after the parts are assembled1 through an opening provided in the edges of the parts4 ,this opening is closed1 after the balls are in place1 by a small pin1 as shown in ,fig4 #dc4 ,the swivel then becomes a ball-bearing joint1 with a freedom of motion characteristic of such bearings4 ,this joint readily responds to every movement of the stem and keeps the hose hanging vertically downward and always free from kinks4 ,its action is illustrated in ,fig4 #dd1 in which it is being used in connection with a carpet renovator4 ,this joint is considered to be the most efficient on the market4 ,it is protected by a patent controlled by a manufacturer of vacuum cleaners4 ,illustration3 ,,fig4 #dd4 ,,action ,,of ,,ball-,,bearing ,,swivel ,,joint4 ,valves are placed at the upper end of the stems by many manufacturers1 to cut off the suction when carrying the renovators from room to room1 and when it is necessary to stop sweeping to move furniture4 ,these valves have nearly always taken the form of a plug cock with tee or knurled handle4 ,they are useful on large installations1 where vacuum control is either inherent in the exhauster or where some means of vacuum control is provided1 as a considerable saving of power may be obtained by closing same1 as will be explained in a later chapter1 and to overcome the unpleasant hissing noise caused by the inrush of air into the renovator when same is held off the floor4 ,illustration3 ,,fig4 #de4 ,,illustration ,,of ,,defects ,,of ,,plug ,,cocks4 ,when the exhauster has a capacity of but one sweeper and when the cleaning is done at times when the building is unoccupied1 there seems to be little need for this refinement1 which has two defects3 first1 the operators will not close the valves3 second1 when they have been closed they are only partly opened1 as indicated in ,fig4 #de4 ,when this occurs1 the portions of the plug1 which are shown stippled1 are quickly cut away by the sand-blast action of the dust1 making it necessary to open the valve a still smaller amount the next time it is operated1 cutting off still more of the plug until a new plug is necessary in order to make the valve again operative4 ,a few attempts have been made to overcome these defects by making the valves self-closing and having them so constructed that when the operator grasps the handle the valve will be forced wide open1 on the principle of the pistol grip4 ,these valves will1 of course1 close whenever the handle is released1 and it is impossible to grasp the handle in any degree of comfort without throwing the valve wide open4 ,however1 since the valve is closed by a spring1 considerable pressure must be applied to the handle in order to keep it open and it acts similar to the ,sandow dumb bell in producing fatigue of the fingers in a short time2 they have not come into general use4 ,the use of valves in the renovator handle is considered by the author to be an expense not justified by the gain in economy and they are no longer included in specifications prepared by him4 ,,chapter ,,vi4 ,,hose4 ,the more important steps in the evolution of the modern vacuum cleaning system can each be attributed to a change in the design or construction of some one of its component parts1 which1 in their former standard design1 have acted as a limiting factor governing the form and size of other and more important parts of the system4 ,that part of the early systems which played the most important role as a limiting factor was one for whose production the builder of the system had to look to other manufacturers3 namely1 the flexible hose connecting the renovator stem to the rigid pipe lines and vacuum producer4 ,the early builders of vacuum cleaning systems naturally adopted a standard article for use as a flexible conduit2 that is1 the vacuum hose which had been used as suction lines for pumps of various characters4 ,for such use it was not necessary that the hose be moved about to any great extent and1 therefore1 its weight was not an important factor and had been sacrificed to strength to withstand collapse and the rough handling to which suction hose is subject4 ,this standard hose was built up of many layers of canvas wound around a rubber tube or lining4 ,a spiral wire was imbedded between the layers of canvas to prevent collapse and the whole was provided with an outer covering of rubber4 ,generally five to seven layers of canvas were used and the resulting hose was not highly flexible4 ,when used as a flexible conduit in connection with a vacuum cleaning system it became necessary to constantly move the hose back and forth and around the room to be cleaned4 ,it was also necessary to limit the weight of the hose to that which could be easily handled by one person4 ,this led to the adoption of small sizes of the then standard hose1 -in4 diameter being first used1 but soon this was abandoned in favor of #a-;in4 diameter hose weighing nearly #a lb4 per foot of length1 which is the maximum weight that can be conveniently handled by one person4 ,this size hose has become the standard for all systems maintaining a vacuum at the separators of #aj in4 of mercury or more4 ,owing to its lack of flexibility this type of hose is easily kinked and is damaged by the pulling out of such kinks1 causing the tubing or lining to become separated from the canvas and to collapse1 rendering the hose useless4 ,there is also considerable wear at the point of connection to the stems of renovators1 where rigid connections are used4 ,the outside of this hose1 being rubber1 is always liberally covered with soap-stone when it leaves the manufacturer1 and when new hose is dragged about over carpets1 it frequently soils same to a greater degree than they are cleaned by the renovator4 ,when this hose has been in use about twice as long as is necessary to wear off the soap-stone1 its appearance becomes far from handsome and is not considered to be in keeping with the nickel-plated appliances which are furnished with the cleaning tools4 ,to overcome this objection1 an outer braid has been applied generally over the rubber coating1 thus adding further to its already great weight4 ,what was perhaps the first type of hose to be produced especially for use with vacuum cleaning systems was that in which the fabric was woven in layers1 instead of being wrapped spirally around the central tube or lining4 ,steam was introduced into the lining1 vulcanizing the lining and firmly uniting the whole mass4 ,this hose was made #a in4 in diameter1 without any metal re-inforcement1 and was covered with the usual rubber coating and with braid1 when ordered4 ,this hose weighed #ab oz4 per lineal foot and #a-;in4 diameter was still the largest that could be easily handled4 ,the first attempt to produce a light-weight hose for use with vacuum cleaning systems was by covering a spiral steel tape with canvas4 ,the air leakage through this hose was found to be so high that its use resulted in loss of efficiency of the cleaning plant and it was found necessary to line the hose with rubber4 ,this rubber-lined hose is made in larger sizes than formerly used and #b-;in4 diameter hose weighs approximately #ad oz4 per lineal foot4 ,it is also much more flexible than the #a-;in4 hose formerly used4 ,the introduction of this type made it possible to use larger hose in connection with vacuum cleaning systems and permitted the use of a lower vacuum at the separators1 with the same results at the carpet renovator1 and a larger quantity of air when using the brushes and other renovators4 ,without this type of hose the low-vacuum1 large-volume systems would be impractical4 ,another type of hose has been recently introduced in which a wire is woven into the fabric of the hose and the rubber lining vulcanized into place as already described4 ,no outer coating of rubber is used and1 therefore1 no braid is necessary4 ,this gives a light-weight hose of great flexibility and neat appearance and is undoubtedly the best hose for residence work4 ,it is more costly than the steel tape hose which is recommended for office building and factory use1 where appearance is not important4 ,illustration3 ,,fig4 #df4 ,,bayonet ,,type ,,of ,,hose ,,coupling1 ,,introduced ,,by ,,the ,,american ,,air ,,cleaning ,,company4 ,hose ,couplings4--,the earlier systems used couplings having screw-threaded ground joints1 similar to those which were then in use on hose intended to withstand pressure4 ,these couplings require considerable time to connect and disconnect and the threads are easily damaged by dragging the hose about4 ,the exposed metal parts of the couplings are liable to scratch furniture4 ,to overcome the time required to connect and disconnect the screw-coupling1 the ,american ,air ,cleaning ,company introduced the bayonet type of coupling1 as illustrated in ,fig4 #df4 ,this coupling is not readily damaged by rough handling1 but it has metal surfaces exposed which will scratch furniture4 ,both of these couplings have the disadvantage that the air current in the hose must always be in the same direction and the same end of the hose must always be next to the renovator handle4 ,both of these features tend to increase the wear on the hose1 and the reversal of the air current to remove stoppages is not possible4 ,the coupling produced by the ,sanitary ,devices ,manufacturing ,company has a piece of steel tubing fitted into each end of the hose and secured by means of a brass slip-coupler fitting over the tubing4 ,all ends being alike1 the reversal of the hose is possible with this form of coupling4 ,however1 the metal coupler is liable to mar furniture and sometimes there is trouble with the couplings pulling apart4 ,illustration3 ,,fig4 #dg4 ,,all ,,rubber ,,hose ,,coupling ,,used ,,by ,,the ,,spencer ,,turbine ,,cleaner ,,company4 ,much of the hose in use today is provided with 8pure gum0 ends are vulcanized in place1 it is necessary to take the hose of metal tubing is slipped inside of these ends to make a coupling4 ,with this arrangement there is no metal exposed to mar furniture and the hose lengths are reversible4 ,however1 there is some trouble from the couplings pulling apart4 ,since these ends are vulcanized in place1 it is necessary to take the hose to a rubber repair shop whenever the hose breaks back of the coupling1 which occurs frequently when rigidly attached to the stem of the renovator4 ,these repair shops are much more numerous than a few years ago and this drawback is not a serious one4 ,another form of coupling used by the ,spencer ,turbine ,cleaner ,company is the all-rubber male and female end1 as illustrated in ,fig4 #dg4 ,this has the advantage over the metal-slip couplings and the coupling with pure gum ends in that when it is properly locked it cannot be pulled apart4 ,it is absolutely air tight1 which is true of no other coupling4 ,but it does not permit the reversal of the hose and is1 therefore1 recommended for use only with hose of #a-;in4 diameter or larger1 where there is less liability of stoppage1 and where the ball-bearing swivel is used at the connection to the stem1 preventing excessive wear at this point4 ,the pure gum ends1 with the internal-slip coupler1 is considered to be the most satisfactory for use in all cases1 except as above stated4 ,hose ,friction4--,hose friction plays an important part in the action of any vacuum cleaning system4 ,in fact1 where #a-;in4 hose is used1 it becomes a limiting factor in the capacity of the system to perform some kinds of cleaning4 ,there are several tables of hose friction published by the manufacturers of vacuum cleaning systems1 all of which appear to have been based on a constant velocity within the hose equal to that which would be obtained if the air were at atmospheric pressure throughout the entire length of the hose4 ,but in practice the air is admitted to the hose from the renovator at a considerably lower absolute pressure of from #be in4 to #bg in4 of mercury1 and is1 therefore1 moving at a higher velocity4 ,as the pressure is decreased by the friction loss in the hose1 the velocity constantly increases with the expansion of the air4 ,the results of many tests made by the author during the past seven years1 with hose ranging from #a-;in4 to #b-;in4 diameter and with an entering vacuum ranging from #j to #g in4 of mercury and a friction loss of from #a in4 to #be in4 of mercury1 indicate a close agreement with the formula given in ,prof4 ,william ,kent's 8,mechanical ,engineer's ,pocketbook10 which is based on the formula3 _/pd ,q c _/ --- w,l ,q free air in cubic feet per minute4 c a constant which was determined by ,d',arcy as approximately #fj4 p the loss of pressure in pounds per square inch4 d the diameter of pipe in inches4 ,l the length of pipe in feet4 w the density of the entering air in pounds per cubic foot4 ,reducing the pressure loss to inches of mercury and using in lieu of w1 r which is the ratio of the average absolute pressure in the pipe to atmospheric pressure1 this formula becomes3 _/pd ,q #caj4c _/ --- ,lr ,to permit the rapid calculation of the air quantity which can be passed through a hose1 the author has prepared the diagram shown in ,fig4 #dh4 ,to use this table1 look up the friction loss in the hose in the right hand margin1 pass along the horizontal line to the left until it intersects the line inclined at an angle of #de toward the left1 indicating the length of the hose4 ,from this intersection pass vertically to the line inclined at approximately #cj toward the left1 representing the diameter of the hose4 ,the quantity in the left-hand margin1 opposite the horizontal passing through this intersection1 represents the quantity of air which would pass through this hose in cubic feet at the average density in the hose4 ,to correct this quantity to free air1 step off the distance on the vertical line from the bottom of the table1 representing the average degree of vacuum in the hose1 to its intersection with the curved line near the bottom of table4 ,transfer this distance vertically downward on the left hand margin from the quantity first read on this margin4 ,the quantity opposite the lower end of this distance will be the cubic feet of free air per minute passing through the hose under these conditions4 ,the line inclined towards the right1 which passes through the intersection of lines representing hose diameter1 and the horizontal line representing the cubic feet of air passing through the hose at actual density in same1 shows the actual velocity in the hose in feet per second4 ,for friction loss over #aj in4 of mercury1 use the figures at the right hand of the lower margin1 instead of those in the right hand margin1 and pass vertically to the hose diameter4 ,then proceed as before4 ,as these high frictions are seldom used in practice1 this departure has been made in order to reduce the size of the diagram4 ,illustration3 ,,fig4 #dh4 ,,chart ,,for ,,determining ,,hose ,,friction4 ,to illustrate how much the friction tables1 based on air at atmospheric density1 vary from actual results1 two tests made by the author are given4 ,in the first test it was desired to pass #fh cu4 ft4 of free air per minute through a -in4 diameter orifice at the end of #ajj ft4 of #a-;in4 diameter hose4 ,tests on larger hose showed that1 to permit this quantity of air to pass through the orifice1 a vacuum at the orifice of #b4f in4 mercury was necessary4 ,the most rational table the writer could find indicated that the friction loss in the hose should be #ah in4 mercury1 and the final vacuum necessary at the hose cock would have to be #bj4f in4 mercury4 ,on test it was found that1 with #bd4h in4 vacuum at the hose cock1 but #ej cu4 ft4 of free air per minute was passing1 with a vacuum at the orifice of #a4f in4 mercury1 showing a friction loss of #bc4b in4 mercury4 ,with the smaller quantity of air passing1 the same friction table indicated a friction loss1 with this quantity of air1 of but #i4h in4 mercury1 or #ci of that actually observed4 ,checking the results of the test with the diagram 7,fig4 #dh7 gives #ej cu4 ft4 of free air1 with a friction loss of #bc in4 mercury4 ,to illustrate more clearly the effect of the increase of velocity on the friction loss1 the actual vacuum in the hose has been computed for each #aj ft4 of its length and curves drawn through these points4 ,the results are shown in ,fig4 #di4 ,the straight line indicates the vacuum which should exist were the velocity in the hose constant throughout its length1 and the curved line shows the vacuum in the hose when the effect of the increasing velocity1 due to the rarefaction of the air1 is considered4 ,the wide variation in the results shows clearly the error in the former assumption of a constant velocity in the hose throughout its length4 ,another test1 in which #dd cu4 ft4 of free air was passed through #ajj ft4 of #a-;in4 diameter hose1 is shown graphically in ,fig4 #ej1 which discloses that the assumption of a constant velocity in the hose produces an error of #ce in the results1 indicating a loss of but #g4h in41 when the actual loss is #ab in4 mercury4 ,naturally1 the lower the final vacuum at the hose cock1 the less will be the error due to the assumption of constant velocity in the hose4 ,tests with #a-;in4 hose gave results which agree substantially with the result given in tables already published1 and it was this condition that led to the discovery of the error in the assumption stated4 ,illustration3 ,,fig4 #di4 ,,effect ,,of ,,increase ,,of ,,velocity ,,on ,,the ,,friction ,,loss4 ,effect of ,hose ,friction4--,as any increase in the degree of vacuum necessary to be maintained at the vacuum producer over that maintained within the renovator requires a greater expenditure of power1 without any increase in the efficiency or speed of cleaning1 it is essential that the friction loss in the air conduit from the renovator to the vacuum producer should be made as small as possible4 ,the friction loss in the hose is the greatest loss in any part of the system1 being the smallest in diameter1 and its reduction to the lowest figure possible is of vital importance4 ,take1 for example1 the use of a ,type ,a renovator with a vacuum within the renovator of #d in4 mercury and with #bi cu4 ft4 of air passing through same4 ,the friction loss1 with varying lengths of different-sized hose1 will be as follows3 ,,table #f4 ,,vacuum ,,at ,,hose ,,cock ,,with ,,type ,a ,,renovators ,,and ,,with ,,varying ,,lengths ,,of ,,different-,,sized ,,hose4 ---------------------------------------- - ,length1 in ,feet4 ,size of ,hose1---------------------------- #ajj #ge #ej #be ,in4 ,diameter4---------------------------- ,vacuum at hose cock1 in4 hg4 ---------------------------------------- - #a #aj #h #g #e #a #f #e4g #e4be #d4he #a #e4j #d4he #d4ge #d4fb ---------------------------------------- - ,illustration3 ,,fig4 #ej4 ,,another ,,test ,,showing ,,friction ,,loss ,,due ,,to ,,velocity4 ,this indicates1 first1 that a much lower friction loss will result with the use of larger hose than is the case with the smaller size4 ,note1 also1 that the difference in the final vacuum at the hose cock is much more uniform when the larger-sized hose is used in varying lengths4 ,since it is desired to maintain a constant vacuum at the renovator at all times and it is also desirable to be able to vary the length of hose to suit the conditions of the work1 while it is not convenient to vary the vacuum at the hose cock1 much more uniform results will be possible when larger hose is used4 ,if the smaller hose is used in varying lengths and a practically uniform vacuum is maintained at the hose cock1 the quantity of air and the vacuum at the renovator will vary4 ,if #a-;in4 hose is used and the vacuum at the hose cock be maintained at #aj in4 mercury1 the air quantities and vacuum at the renovator will be approximately3 ,,table #g4 ,,air ,,quantities ,,and ,,vacuum ,,at ,,renovator ,,with #a-;,,in4 ,,hose ,,and #aj-;,,in4 ,,vacuum ,,at ,,hose ,,cock4 -------------------------------------- ,vacuum at ,length of ,renovator1 ,air1 ,h4 ,p4 at ,hose1 feet4 in4 hg4 cu4 ft4,hose ,cock4 -------------------------------------- #ajj #d #bi #j4hj #ge #e #cb #j4hhe #ej #f #cd #j4id #be #g #cg #a4jb -------------------------------------- ,from this it is evident that the vacuum within the renovator will be increased above that necessary for economical cleaning4 ,it will require somewhat more effort to push the cleaner over the carpet and also a slightly greater expenditure of power at the hose cock to operate the cleaner with a short than with a long hose4 ,however1 the author does not consider that either the increase of effort to push the renovator or the increase of power will be sufficient to prohibit the use of #a-;in4 hose with the ,type ,a renovator4 ,if we use #a-;in4 hose with ,type ,a renovator and maintain a vacuum of #f in4 of mercury at the hose cock1 the resulting vacuum and air displacement at the renovator will be3 ,,table #h4 ,,air ,,quantities ,,and ,,vacuum ,,at ,,renovator ,,with #a-;,,in4 ,,hose ,,and #f-;,,in4 ,,vacuum ,,at ,,hose ,,cock4 -------------------------------------- ,vacuum at ,length of ,renovator1 ,air1 ,h4 ,p4 at ,hose1 feet4 in4 hg4 cu4 ft4,hose ,cock4 -------------------------------------- #ajj #d #bi #j4dc #ge #d4g #cj #j4dde #ej #e4j #cc #j4ddh #be #e4d #ce #j4eah -------------------------------------- ,this table shows a more uniform degree of vacuum at the renovator with the varying length of hose1 but the greatest difference is in the horse power required at the hose cock to accomplish the same results at the renovator4 ,if we use #a-;in4 hose with ,type ,a renovator1 the vacuum at the hose cock can be reduced to #e in4 mercury and a practically constant vacuum will be obtained at the renovator1 with an expenditure of #j4cf ,h4 ,p4 at the hose cock4 ,with the ,type ,c renovator where the vacuum within the renovator is maintained at #d in4 mercury1 with #dd cu4 ft4 of free air per minute passing through the renovator1 the resulting vacuum at the hose cock1 with various lengths of the three sizes of hose1 will be as follows3 ,,table #i4 ,,vacuum ,,at ,,hose ,,cock1 ,,with ,,type ,c ,,renovators ,,and ,,various ,,lengths ,,of ,,three ,,sizes ,,of ,,hose4 ---------------------------------------- -- ,length1 in ,feet4 ,size of ,hose1----------------------------- ,in4 ,diameter4 #ajj #ge #ej #be ----------------------------- ,vacuum at hose cock1 in4 hg4 ---------------------------------------- -- #a #ai #ad #aj #f4g #a #g4e #f4be #e4e #d4g #a #e4a #d4hj #d4ej #d4be ---------------------------------------- -- ,referring to ,fig4 #ag1 ,chapter ,,iii1 it will be noted that ,type ,c renovator will not accomplish much in the way of cleaning with a vacuum in the renovator lower than #d in4 mercury4 ,therefore1 if we use this type of renovator1 with #a-;in4 diameter hose1 its length should be limited to #ej ft41 for if we use a vacuum higher than #aj in4 at the hose cock1 there will be too much increase in the vacuum at the renovator when short hose is used to allow easy operation1 and if we use longer hose with #aj-;in4 vacuum at the hose cock1 there will be a reduction in the vacuum at the renovator and effective cleaning cannot be accomplished4 ,also1 the power required at the hose cock to pass #dd cu4 ft4 of air1 with a vacuum of #ai in4 mercury1 required to produce a vacuum of #d in4 at the renovator with #ajj ft4 of #a-;in4 hose1 will be #c4c ,h4 ,p41 which is prohibitive when compared with that required with the use of larger hose1 i4 e41 #j4hbe ,h4 ,p4 with #a-;in4 hose and #j4ei ,h4 ,p4 with #a-;in4 hose4 ,the ,type ,f renovators tested by the author will show even wider variations in the vacuum required at the hose cock with the various lengths and diameters of hose than is given for ,type ,c renovator4 ,however1 the type ,f renovator1 which is now used by the ,spencer ,turbine ,cleaner ,company1 having a cleaning slot #ae in4 long and in4 wide throughout its length4 passes #dd cu4 ft4 of free air per minute1 with a vacuum under the renovator of #d in4 mercury and the resulting vacuum at the hose cock will be the same as that given in the case of the ,type ,c renovator4 ,when a bare floor renovator of the bristle-brush type is attached to the hose1 the effect is practically the same as when the end of the hose is left wide open1 as the open character of the brush prevents the formation of any vacuum in the renovator4 ,therefore1 sufficient air must pass through the renovator to create a friction loss in the hose equal to the vacuum at the hose cock4 ,as practically all systems are arranged to maintain a constant vacuum at the vacuum producer and as the pipe friction is generally less than the hose friction1 the vacuum at the hose cock will be practically the same when operating a floor brush as with a carpet renovator4 ,assuming that #aj in4 mercury is maintained at the hose cock with #a-;in hose1 #f in4 with #a-;in4 hose1 and #e in4 with #a-;in4 hose1 the quantity of air which will pass through a floor brush with various sizes and lengths of hose will be3 ,,table #aj4 ,,air ,,quantities ,,through ,,floor ,,brush ,,operated ,,in ,,conjunction ,,with ,,type ,a ,,renovators4 ---------------------------------------- ------- ,hose ,length1 in ,feet4 ,size of ,hose1---------------------------------- ,in4 ,diameter4 #ajj #ge #ej #be ---------------------------------- ,cubic feet of free air per minute4 ---------------------------------------- ------- #a #db #dh #fj #hf #a #fb #gb #hf #abe #a #ie #aaj #ace #aij ---------------------------------------- ------- ,the quantities given for the shorter hose lengths are higher than will be observed in actual practice1 due to the increase in the pipe friction1 which will depend on the length of the pipe lines4 ,however1 the results will illustrate the great increase in the quantity of air which will pass these bare floor brushes when operated on the same system with carpet renovators4 ,if the same number of bare floor renovators are to be used at one time as there will be carpet renovators at some other time1 that is1 if the sweeper capacity must be maintained when using bare floor brushes as when using carpet renovators1 a much larger air exhausting plant must be installed than would be necessary to operate that number of carpet renovators4 ,if it were possible to so arrange the schedule of cleaning operations that bare floor brushes were never used at the same time as carpet renovators1 the vacuum at the machine might be reduced when operating the floor brushes to a point that would reduce the quantity of air passing to within the capacity of a machine designed to operate the same number of carpet renovators4 ,unfortunately1 this condition rarely exists and1 therefore1 the vacuum must be maintained at the degree necessary to operate the carpet renovators that may be in use at the same time with the floor brushes4 ,it is also evident that if the length of hose used with bare floor brushes could be limited to the maximum ever used with the carpet renovators1 a reduction in the capacity of the exhauster necessary could be made4 ,this is another condition which the designer of the system cannot control4 ,most ,economical ,hose ,size for ,carpet and ,floor ,renovators4--,the horse power required at the hose cock to operate the bare floor brushes with each of the different sizes and lengths of hose is3 ,,table #aa4 ,,horse ,,power ,,required ,,at ,,hose ,,cock ,,to ,,operate ,,bare ,,floor ,,brushes ,,in ,,conjunction ,,with ,,type ,a ,,renovators4 ---------------------------------------- - ,length1 in ,feet4 ,size of ,hose1---------------------------- ,in4 ,diameter4 #ajj #ge #ej #be ---------------------------- ,horse power at hose cock4 ---------------------------------------- - #a #a4af #a4cb #a4fe #b4ch #a #j4ib #a4jf #a4bg #a4ch #a #a4ae #a4cb #a4fb #b4bh ---------------------------------------- - ,this shows that where bare floor or wall brushes of the bristle type are used in conjunction with carpet renovators on any system and with ,type ,a carpet renovator1 #a-;in4 diameter hose will give the lowest power consumption4 ,when either ,type ,c or ,f renovator is used in combination with bristle-type brushes1 the use of #a-;in4 diameter hose must be abandoned in lengths over #ej ft4 and the vacuum at the hose cock must be maintained at #aj in4 mercury4 ,with #a-;in4 hose1 it will be necessary to maintain a vacuum at the hose cock of #g in4 mercury1 and1 with #a-;in4 hose1 #e in4 will be sufficient1 provided we continue to use #ajj ft4 of hose in the case of the larger sizes4 ,the free air passing a brush type of bare floor renovator under these conditions will be3 ,,table #ab4 ,,free ,,air ,,passing ,,brush ,,type ,,of ,,bare ,,floor ,,renovator ,,operated ,,in ,,conjunction ,,with ,,type ,c ,,renovators4 ---------------------------------------- ------- ,length1 in ,feet4 ,size of ,hose1---------------------------------- ,in4 ,diameter4 #ajj #ge #ej #be ---------------------------------- ,cubic feet of free air per minute4 ---------------------------------------- ------- #a #db #dh #fj #hf #a #fh #gf #ib #acj #a #ie #aaj #ace #aij ---------------------------------------- ------- ,this shows an increase in the volume of air passing the floor brush with #a-;in4 hose1 while a higher vacuum is now carried at the hose cock than was necessary when ,type ,a renovator was used in conjunction with the bristle-type of floor renovator4 ,the horse power at the hose cock will now be3 ,,table #ac4 ,,horse ,,power ,,at ,,hose ,,cock ,,with ,,brush ,,type ,,of ,,bare ,,floor ,,renovator ,,operated ,,in ,,conjunction ,,with ,,type ,c ,,renovators4 -------------------------------------- ,length1 in ,feet4 ,size of ,hose1------------------------- ,in4 ,diameter4 #ajj #ge #ej #be ------------------------- ,horse power at hose cock4 -------------------------------------- #a #a4af #a4cb #a4fe #b4ch #a #a4ai #a4cf #a4fj #b4bf #a #a4ae #a4cb #a4fb #b4bh -------------------------------------- ,with this combination of floor and carpet renovators1 there is no difference in the power consumption when any one of the three sizes of hose is used4 ,however1 there is a considerable increase in the quantity of air passing the larger hose4 ,this leads to the statement made by some manufacturers that this increase in air volume results in more efficient cleaning4 ,tests given in ,chapter ,,iii indicate that increase in air volume does not result in any more rapid or efficient cleaning of carpets4 ,the results of actual use of the bare floor brush of the bristle type show no gain when cleaning bare floors4 ,as stated in ,chapter ,,iv1 the felt-faced renovator1 being more effective while it requires less air4 ,in other words1 it is the degree of vacuum within the cleaner and not the quantity of air which produces the cleaning in all cases where any degree of vacuum is possible4 ,when intimate contact between the cleaner and the surface cleaned cannot be had1 the volume of air determines the efficiency of cleaning4 ,however1 the author does not consider that an exhaustion of more than #fj to #gj cu4 ft4 of free air through cleaners of this type will increase the efficiency to such an extent as to justify the increase of power necessary to adapt a system to larger volumes4 ,the author considers that with a system in which brushes of the bristle type are to be used1 the exhauster should have a capacity of #gj cu4 ft4 of free air per minute4 ,such a system is termed by the author a 8large volume system10 as already mentioned in ,chapter ,,iv4 ,when the felt-covered floor renovator is used instead of the brush1 the vacuum within this renovator must not be permitted to rise above #b in4 or the operation of the renovator on the floor will be difficult4 ,to accomplish this1 it is necessary to provide openings in the ends of the cleaning slot1 as has been explained in ,chapter ,,iv4 ,if the vacuum at the hose cock be assumed as #aj in4 with #a-;in hose1 #f in4 with #a-;in4 hose1 and #e in4 with #a-;in4 hose1 and the vacuum within the felt-covered floor renovator be maintained at #b in4 mercury the cubic feet of free air passing the renovator with the various sizes and lengths of hose will be3 ,,table #ad4 ,,cubic ,,feet ,,of ,,free ,,air ,,passing ,,the ,,felt-,,covered ,,floor ,,renovators ,,operated ,,in ,,conjunction ,,with ,,type ,a ,,renovators4 ---------------------------------------- ----- ,length1 in ,feet4 ,size of ,hose1-------------------------------- ,in4 ,diameter4 #ajj #ge #ej #be -------------------------------- ,free air1 cubic feet per minute4 ---------------------------------------- ----- #a #cf #dc #ed #gd #a #di #ef #fh #id #a #fh #gh #id #acj ---------------------------------------- ----- ,these figures show a considerable reduction from those obtained with the brush type of floor renovator1 particularly when the larger sizes of hose are used1 and considerable reduction can be made in the capacity of the exhauster and still obtain the best results when using carpet renovator and bare floor renovator simultaneously4 ,the horse power at the hose cock required to operate these felt-faced floor renovators with different sizes and lengths of hose are3 ,,table #ae4 ,,horse ,,power ,,required ,,at ,,hose ,,cock ,,to ,,operate ,,felt-,,covered ,,floor ,,renovators ,,in ,,conjunction ,,with ,,type ,a ,,renovators4 ---------------------------------------- ,length1 in ,feet4 ,size of ,hose1--------------------------- ,in4 ,diameter4 #ajj #ge #ej #be --------------------------- ,horse power at hose cock4 ---------------------------------------- #a #a4j #a4ai #a4di #b4je #a #j4gb #j4hc #a4j #a4ci #a #j4gi #j4ic #a4ac #a4ef ---------------------------------------- ,in this case1 the #a-;in4 hose is the most economical size to use1 as was the case with the brush renovators4 ,however1 the advantage over the #a-;in4 hose is not as great as with the brush renovator4 ,with this type of renovator1 the manufacturer has some control over the length of hose which the operator will use in connection with the bare floor renovator1 as he may open the ends of the renovator just sufficiently to produce #b in4 of vacuum under same with1 say1 #ej ft4 of hose4 ,then1 if the operator should attempt to use the renovator with #be ft4 of hose1 it will stick and push hard and he will soon learn that a longer hose is necessary4 ,conditions for ,plant of ,small ,power4--,for locations where it is desirable to sacrifice efficiency somewhat to reduction in the amount of power required1 as in residences1 the ,type ,a carpet renovator may be used and the vacuum under the same reduced to #b in4 mercury1 which will still do effective cleaning1 but at a slower rate1 as was shown by tests in ,chapter ,,iii4 ,this requires not exceeding #bj cu4 ft4 of free air per minute4 ,with this quantity of air the velocity in the hose must be considered as1 in order to have a clean hose at all times1 it is necessary to maintain a velocity in the hose of not less than #dj ft4 per second4 ,referring to the diagram1 ,fig4 #dh1 it will be seen that this velocity will not be obtained in any hose larger than #a in4 and this is1 therefore1 the largest size which can be used4 ,in all the former cases the velocity was so much in excess of this minimum that its consideration was not necessary4 ,with a vacuum of #b in4 of mercury in the renovator and #bj cu4 ft4 of air passing1 the vacuum at the hose cock will be3 ,,table #af4 ,,vacuum ,,at ,,hose ,,cock1 ,,with #b-;,,in4 ,,vacuum ,,at ,,type ,a ,,renovator4 ---------------------------------------- - ,length1 in ,feet4 ,size of ,hose1---------------------------- ,in4 ,diameter4 #ajj #ge #ej #be ---------------------------- ,vacuum at hose cock1 in4 hg4 ---------------------------------------- - #a #d #c4e #c #b4e #a #b4f #b4de #b4c #b4ae ---------------------------------------- - ,in this case the increase in vacuum at the renovator would not be objectionable as1 with #d in4 vacuum at the hose cock1 the vacuum at the renovator would never reach the standard used with the former deductions and the volume of air passing could1 therefore1 never reach #bi cu4 ft4 ,any increase1 due to the use of shorter hose1 would1 therefore1 be an advantage in its approach toward the standard set for the larger plants4 ,therefore1 we will assume that a vacuum of #d in4 mercury will be maintained at the hose cock with #a-;in4 hose and a vacuum of #b in4 at the hose cock with #a-;in4 hose4 ,the renovators for bare floor work will be the felt-covered type and will be opened at the ends just sufficiently to limit the vacuum within the same to #b in4 mercury when operating with #be ft4 of hose4 ,this will require the passage of #dj cu4 ft4 of free air per minute when #a-;in4 hose is used and #ce cu4 ft4 when #a-;in4 hose is used4 ,the horse power at the hose cock will be #j4ci ,h4 ,p4 with the #a-;in4 diameter hose and #j4ag ,h4 ,p4 with the #a-;in4 hose4 ,here again we see that the #a-;in4 hose is the more economical to use4 ,if bristle brushes are used with this system at the same time that carpet renovators are in use1 the quantity of air which will have to pass them1 in order to maintain the vacuum on the system at the proper point to do effective cleaning with the carpet renovators1 will be3 ,,table #ag4 ,,air ,,quantities ,,when ,,bristle ,,bare ,,floor ,,renovators ,,are ,,used ,,in ,,conjunction ,,with ,,type ,a ,,carpet ,,renovators ,,at #b ,,in4 ,,hg4 ---------------------------------------- -- ,length of ,hose1 in ,feet4 ,size of ,hose1----------------------------- ,in4 ,diameter4 #ajj #ge #ej #be ----------------------------- ,free air1 cu4 ft4 per minute4 ---------------------------------------- -- #a #cj #cf #db #fj #a #da #dh #fj #hj ---------------------------------------- -- ,the use of these brushes in plants of more than one-sweeper capacity would require the use of an exhauster of greater capacity than is required for either the carpet or the bare floor renovator4 ,where the plant is of but one-sweeper capacity1 the quantity of air that would pass these brushes1 were the plant of proper capacity to serve the carpet and floor renovators1 would not be sufficient to do effective work1 as was explained in ,chapter ,,iv4 ,in such cases1 this arrangement should be prohibited4 ,a system of the type just described is what has been termed by the author as a 8small volume0 plant in ,chapter ,,iv4 ,limit of ,length for ,hose4--,the author has made the deductions in this chapter1 using #ajj ft4 of hose as the maximum length4 ,this is considered to be the greatest length that should be used4 ,the adoption of a shorter length is recommended by many manufacturers1 but the author does not consider that the advantage to be obtained by the adoption of a shorter length justifies the additional expense of piping which will result in many cases4 ,this will be governed by the character of the building and1 in many cases1 it will be possible to use #ej ft4 as a maximum4 ,it has been the practice of the author to lay out his installations so that any point on the floor of any room may be reached in the most direct line with #ge ft4 of hose4 ,when this is done #ajj ft4 of hose will easily clean any part of the walls or ceilings and give an ample allowance for running around furniture or other obstructions4 ,the figures in this chapter will demonstrate to the reader the part that the cleaning hose plays as a limiting factor in the operation of a vacuum cleaning system and shows the care that must be exercised in the selection of the proper hose for each condition4 ,,chapter ,,vii4 ,,pipe ,,and ,,fittings4 ,as we continue to follow the dust-laden air in its passage toward the vacuum producer we next encounter that portion of the conduit which is permanently and rigidly fixed in place in the building2 namely1 the pipe line1 its fittings and other appliances4 ,hose ,inlets4--,the first portion of this conduit which we must consider is the point where the hose is attached to the pipe line2 that is1 the inlet1 or1 as it is often improperly termed1 the 8outlet0 valves4 ,as it is necessary to close the inlets air tight when they are not in actual use1 in order to prevent the entrance of air except through the hose lines in use1 some kind of a cut-off valve must be provided1 as well as a receptacle into which the end of the hose may be connected when desired4 ,with the earlier systems a high degree of vacuum was carried in the pipe lines and the vacuum producers were of small displacement4 ,slight leakage would greatly reduce the capacity of the system and the best form of valve was necessary4 ,the valve adopted was the ordinary ground-seat plug cock1 on account of its unobstructed air passage and air-tight closing4 ,the hose was connected to these cocks either by a ground-joint1 screwed coupling or by a slip coupling similar to those used to unite the sections of the cleaning hose4 ,an inlet cock of this type is illustrated in ,fig4 #ea4 ,these cocks projected about #d in4 beyond the face of the finished wall and formed a considerable obstruction1 especially when located in halls or corridors4 ,in order to reduce the projection into the apartment the manufacturers of the systems using screwed-hose couplings and substituted a projecting nipple closed by a cap screwed in place4 ,the whole projected only in4 beyond the finished wall line4 ,these outlets were suitable for use only with hose having screwed connections4 ,when an attempt is made to remove the cap with the vacuum producer in operation1 there is a tendency for the vacuum to cause the cap to hug the last thread and render its removal difficult4 ,also1 when the suction is finally broken it is accomplished with considerable hissing noise4 ,illustration3 ,,fig4 #ea4 ,,inlet ,,cock ,,to ,,prevent ,,air ,,leakage ,,when ,,not ,,in ,,use4 ,in order to permit the use of the slip type of hose coupling1 a hinged flap valve was substituted for the screwed cap1 a rubber gasket being placed under the cap4 ,this was held firmly in place by the vacuum in the pipe line4 ,the interior of the casting inside of the flap was turned to a slip fit for the end of the hose coupling4 ,with this type of valve and the slip hose coupling1 described in ,chapter ,,vi1 it is possible to reverse the hose to equalize wear and remove obstructions4 ,these inlets have been made with valves that are closed only by gravity when there is no vacuum on the system and many are so constructed that when opened wide they will remain open with the vacuum on the piping4 ,this type of valve will often be opened by the inquisitive person when no vacuum exists in the system and as there are no immediate results1 they may be left open with the result that there will be a very large leakage of air on starting the vacuum producer4 ,this makes it necessary for some one to make a tour of the building in order to close the valve which is open before the system can be efficiently operated4 ,if the vacuum producer is designed to operate several renovators simultaneously1 it may not be discovered that there are any valves open and a considerable amount of power will be wasted4 ,in order to overcome this difficulty it is necessary to provide a spring on the hinge of the flap valve that will automatically close the valve whenever the hose is withdrawn4 ,when the inlets are located in public places they should be fitted with a lock attachment to prevent them from being opened by unauthorized persons4 ,a valve of this type is illustrated in ,fig4 #eb4 ,this valve has a projection on its inner face which engages with a ridge on the hose couplings1 preventing the removal of the hose without slightly raising the cap and making it impossible to accidentally pull the hose out of the inlet4 ,illustration3 ,,fig4 #eb4 ,,type ,,of ,,automatic ,,self-,,closing ,,inlet ,,cock4 ,the particular valve here shown is suitable for use only with the all-rubber hose connection described in ,chapter ,,vi4 ,we must next consider the material of which the conduit itself is to be made4 ,the commercial wrought-iron or mild steel1 screw-jointed pipe1 such as is used for water and steam lines1 is probably the best suited for this purpose and was the first material used4 ,in earlier installations the pipe was galvanized1 but1 owing to the tendency for the zinc coating to form irregularities within the pipe1 its use has been abandoned in favor of the commercial black iron pipe4 ,seamless drawn tubing would undoubtedly make the ideal material for this purpose4 ,however1 the ordinary butt or lap-welded pipe is satisfactory and is now generally used4 ,sheet metal pipe was introduced by one manufacturer but its use was shortly abandoned in favor of the commercial pipe4 ,as joints and changes in direction are necessary in the pipe lines1 some sort of fittings must be used4 ,the ideal conduit for passage of dust-laden air should be of uniform bore and as smooth on the inside as a gun barrel4 ,various attempts have been made to accomplish this result in commercial installations1 one of which is illustrated in ,fig4 #ec4 ,these fittings are made up of three parts for a coupling and four for a branch or change in direction4 ,one of these is screwed on to the end of each piece of pipe1 the pipe butting against a shoulder and the end of the pipe made to register with the bore of the fitting by reaming4 ,this piece is faced true and fitted against the face of the casting1 forming the bend or branch1 or fitted against the piece on the end of the other length of pipe4 ,a thin gasket is placed between them1 a projecting ring on one piece fitting into a groove on the other1 causing the bore of the two halves to register4 ,the two halves are joined together by the ,v-grooved clamp1 held in place by a small bolt4 ,this is theoretically an ideal joint1 but the clamp is not of sufficient strength to withstand the strain of settlement of the building and breakages are frequent4 ,several instances of this character1 particularly on steamers1 have come to the observation of the author1 and there are several buildings which have been roughed in with this type of fitting1 used on concealed piping1 which were found to be useless on the completion of the building1 due to breaking of the joints in inaccessible places4 ,illustration3 ,,fig4 #ec4 8,,smooth ,,bore0 ,,pipe ,,coupling4 ,a modification of this joint which will have ample strength can be made by using standard pipe flanges1 screwing the pipe through the flange and facing the end off in a lathe4 ,fittings could be made with a bore equal to that of the pipe and proper alignment secured by the use of dowel pins1 as illustrated in ,fig4 #ed4 ,the cost of making this joint would be high and they would occupy too much space to be easily concealed in partitions1 furring or other channels usually provided for the reception of such piping4 ,illustration3 ,,fig4 #ed4 ,,joint ,,made ,,of ,,standard ,,pipe ,,flanges4 ,the standard ,durham recessed drainage fitting1 having the inside cored to the bore of the pipe and recesses provided for the threads as used in connection with the modern plumbing system1 if left ungalvanized and having the inside well sand-blasted to remove all rough places1 makes a serviceable fitting4 ,care should be exercised to cut the threads on the piping of proper depth to allow the end of the pipe to come as close to the shoulder of the recess as practicable and to obtain a tight joint4 ,the end of the pipe should be carefully reamed before assembling4 ,these fittings have become standard with nearly all manufacturers and are illustrated in ,fig4 #ee1 which shows the right and wrong way to install same4 ,trouble was experienced on some of the earlier systems using high vacuum with the fittings cutting out on the side subjected to the impact of the dust-laden air4 ,to overcome this trouble one manufacturer re-inforced the fittings by increasing the thickness of metal at the point affected4 ,the trouble was undoubtedly caused by too high a velocity in the pipe line1 as in the case of the small brass stems1 explained in ,chapter ,v4 ,with the introduction of vacuum control and larger pipes1 this trouble disappeared and the special fittings never came into general use4 ,illustration3 ,,right ,,way4 ,,wrong ,,way4 ,use two ,y-branches instead of straight or cleanout tees4 ,in case the latter are used the dirt will shoot by into the other branch4 ,always place ,y-branches so they will turn in the direction of the flow4 ,place the clean-out at right angles to the direction of flow entering the fitting4 ,otherwise it serves as a pocket to catch passing dirt4 ,special care must be exercised to see that there is no opportunity for dirt to collect in the basement drops4 ,above is shown a common wrong way and two possible right ways4 ,,fig4 #ee4 ,,standard ,,durham ,,recessed ,,drainage ,,fittings ,,generally ,,used ,,in ,,vacuum ,,cleaning ,,installations4 ,while the utmost care should be taken to prevent stoppage of the pipe lines these stoppages are likely to occur in the best-constructed lines and ample clean-out plugs should be provided for the removal of such stoppage4 ,brass plugs are the most serviceable for this purpose1 as they are easily removed when necessary and can usually be replaced air tight4 ,the brass clean-outs1 while most satisfactory1 are costly when installed in large sizes4 ,equally satisfactory results can be obtained at a lower cost by using #b-;in4 diameter plugs on all lines #b in4 and over in diameter4 ,illustration3 ,,fig4 #ef4 ,,friction ,,loss ,,in ,,pipe ,,lines4 ,matches are perhaps the most frequent cause of stoppage in pipe lines4 ,stoppage from this cause can be largely avoided by the use of pipe of sufficient size to permit the match to turn a complete somersault within the pipe whenever it catches against a slight obstruction or rough place in the pipe or fittings4 ,a #b-;in4 diameter pipe is just large enough to permit this and smaller sizes of pipe should be avoided whenever possible4 ,pipe ,friction4--,the friction loss in piping follows the same law as that in hose lines and is easily computed by use of the chart 7,fig4 #ef71 which is constructed on the same general principle as the chart of hose friction 7,fig4 #dh74 ,the directions for use of the hose chart apply to the pipe chart4 ,in computing this chart the actual inside diameter of the commercial wrought-iron pipes have been used instead of the nominal diameters1 resulting in an increased capacity for all sizes except #b-;in4 which is less than the nominal diameter4 ,determination of ,proper ,size ,pipe4--,friction in the pipe lines tends to increase the vacuum to be maintained and therefore the power to be expended at the vacuum producer and should be kept as low as possible4 ,the pipe sizes should be made as large as conditions will permit4 ,the limit of size is fixed by the velocity in the pipe4 ,when it is necessary to lift the dirt to any extent1 the velocity should not be allowed to fall below #dj ft4 per second at any time4 ,when the pipe is a vertical drop1 the velocity does not matter as gravitation will assist the air current in removing the dirt4 ,when the line is horizontal a lower velocity than #dj ft4 per second is permissible at times1 provided that this minimum velocity is exceeded at frequent intervals to flush out any dirt that has lodged in the pipe during periods of low velocity4 ,if a ,type ,a renovator is used with #a-;in4 hose and a vacuum of #aj in4 of mercury maintained at the hose cock1 the minimum air passing1 with #ajj ft4 of hose in use1 will be #bi cu4 ft4 of free air per minute1 which is equivalent to #dd cu4 ft4 at #aj in4 of vacuum4 ,the entering velocity in the pipe should be calculated with air at this density4 ,this will give a velocity of #ej ft4 per second in a #a-;in4 pipe1 but only #cj ft4 per second in a #b-;in4 pipe4 ,therefore1 the #a-;in4 pipe is the largest that should be used where lifts occur on a line serving but one ,type ,a renovator with #a-;in hose4 ,when the renovator is tilted at a considerable angle or lifted from the carpet1 as will frequently occur in cleaning operations1 the quantity of air passing the renovator will be upwards of #db cu4 ft4 of free air1 equivalent to #fb cu4 ft4 at #aj-;in4 vacuum4 ,when this occurs the velocity in a #b-;in4 pipe will be #dd ft4 per second1 which will be ample to flush a horizontal line of piping4 ,if #a-;in4 hose is used with a ,type ,a renovator1 the minimum quantity of air will be #bi cu4 ft4 and the vacuum entering the pipe will be #f in4 mercury1 giving an equivalent volume of #cg cu4 ft4 ,this will produce a velocity of #db ft4 per second in a #a-;in4 pipe1 which is the largest that can be used where a lift occurs4 ,however1 when the renovator is lifted free of the carpet1 the air quantity will be #fb cu4 ft4 of free air1 equivalent to #hj cu4 ft4 at #f in4 of vacuum1 and will produce a velocity of #ci ft4 per second in a #b-;in4 pipe4 ,this would be just about sufficient to flush a horizontal line4 ,if #a-;in4 hose were used the air quantity will be #bi cu4 ft4 and the vacuum entering the pipe #e in4 mercury1 equivalent to #ce cu4 ft4 ,this will give a velocity in a #a-;in4 pipe of #dj ft4 per second4 ,when the renovator is raised from the carpet1 the air quantity will be upwards of #ij cu4 ft4 of free air1 equivalent to #aaj cu4 ft4 at the density of that entering the pipe1 and will produce a velocity of #cc ft4 per second in a #c-;in4 pipe4 ,this is too low to thoroughly flush a horizontal pipe4 ,the figures given above are repeated from ,chapter ,,vi and show that the use of #a-;in4 instead of #a-;in4 hose1 permits the use of a larger-sized horizontal pipe line for serving one renovator1 but that the use of #a-;in4 hose1 instead of #a-;in41 will not permit of any enlargement in the pipe size4 ,since we have seen in ,chapter ,,vi that a #a-;in4 hose gives the least expenditure of power when used with a ,type ,a renovator1 there will be no gain from a reduction in the pipe friction due to the adoption of this hose4 ,the dependence on the raising of the renovator from the floor to flush out a larger pipe line should not be carried beyond that to be obtained from a single renovator4 ,that is1 when the pipe must serve more than one renovator at the same time1 the quantity of air that two or more renovators will pass1 if they were raised from the floor at the same time1 should not be used in determining the limiting velocity in the pipe1 as such an occurrence is not likely to be obtained often enough to thoroughly flush the pipe4 ,furthermore1 there will be times when this pipe will have to serve only one renovator and the pipe will not be adequately flushed4 ,when the pipe is serving more than one renovator1 the actual air passing the renovators should be used in determining the maximum size of pipe and it is advisable to use this maximum size in nearly all cases where the structural conditions will permit4 ,these sizes will then be3 ,,table #ah4 ,,pipe ,,sizes ,,required1 ,,as ,,determined ,,by ,,air ,,passing ,,renovators4 ---------------------------------------- - ,pipe ,sizes1 ,in4 ,diam4 ,number of ------------------ ,renovators,cu4 ,ft4 ,with #a-;in4,with #a-;in4 in ,use4 per min4 ,hose4 ,hose4 ---------------------------------------- #a #bi #b #b #b #eh #b #b #c #hg #c #c #d #aaf #c #c #e #ade #c #c #f #agd #d #d ---------------------------------------- ,using these maximum sizes1 the friction loss in a pipe line1 with carpet renovators in use exclusively1 will be3 ,,table #ai4 ,,friction ,,loss ,,in ,,pipe ,,lines1 ,,with ,,carpet ,,renovators ,,in ,,use ,,exclusively4 ---------------------------------------- ------ ,friction ,loss per #ajj ,feet1 ,inches4 ,number of------------------------------------- ,sweepers4,with #a-;in4 hose4 ,with #a-;in4 hose4 ---------------------------------------- ------ #a #j4bj #j4jf #b #j4cj #j4bj #c #j4bd #j4ag #d #j4ai #j4ac #e #j4cj #j4bb #f #j4bd #j4ag ---------------------------------------- ------ ,these friction losses are figured with a density of air in the pipe equal to #f-;in4 vacuum in case of the #a-;in4 hose and #aj-;in4 vacuum in case of the #a-;in4 hose1 which will be the density of the air entering the pipe1 while the average density should be used in order to give correct results4 ,if the pipe line is not over #djj ft4 equivalent length the results will be approximately correct4 ,these results show1 first1 that the friction loss in pipe lines is much lower than that in the hose lines used with the same system2 second1 that the higher vacuum in the pipe causes greater loss1 an argument in favor of the use of larger hose4 ,illustration3 ,,figs4 #eg-fj4 ,,diagrams ,,showing ,,operation ,,of ,,brush ,,and ,,carpet ,,renovators ,,under ,,different ,,conditions4 ,these friction losses are obtained only when carpet renovators are used exclusively and all the renovators are held in the proper position to perform the most economical cleaning4 ,in actual practice this condition will not exist except when one renovator is used4 ,where more than one renovator is in use simultaneously1 some of the renovators will be raised from the floors at the time others are in position to do effective cleaning and will admit a greater quantity of air1 increasing the friction4 ,this is not a serious condition as the time that the renovators will be raised is only a small part of the total time spent in cleaning and will merely reduce the efficiency of the other renovators temporarily4 ,however1 when brushes or floor renovators are used at the same time as the carpet renovators1 there will be a continuous flow of air in greater quantities through these brushes1 which will permanently increase the friction loss4 ,the use of a single brush or floor renovator with the same sized pipe as is necessary to operate the carpet renovator will not reduce the efficiency of the brush1 as a high degree of vacuum at the brush or floor renovator is not necessary or even permissible and a further slight reduction will not affect the operation of these renovators4 ,when a brush or floor renovator is used on the furthest outlet from the vacuum producer at the same time that carpet renovators are being used on outlets nearer the vacuum producer1 the larger quantity of air passing the brush will tend to reduce the vacuum at the hose cock to which the carpet renovator is attached and thereby impair its efficiency4 ,for example1 if we have a brush renovator connected through #ajj ft4 of #a-;in4 hose to an outlet at the end of a pipe line #djj ft4 long1 properly designed to serve two carpet renovators1 the vacuum at the separators should be maintained at #aj-;in41 plus #b #j4bj plus #b #j4cj1 or #aa in4 of mercury4 ,suppose that this vacuum is automatically maintained at this point and a carpet renovator be attached #bjj ft4 from end of pipe 7,fig4 #eg74 ,the quantity of air passing through the #b-;in4 pipe ,b-,c will be approximately #bi plus #dj or #fi cu4 ft41 and the friction loss in this pipe will be #a4a in4 ,the vacuum maintained at the outlet ,b 7,fig4 #eg7 will be #i4i in4 or approximately the correct vacuum to maintain #d-;in4 vacuum at the renovator 8a40 ,the friction loss in the pipe line from ,b to ,a will be #j4g in4 and the resulting vacuum at the hose cock ,a will be #i4b in4 ,the quantity of air passing the brush will be #dj cu4 ft4 ,under these conditions there will be no loss in efficiency of cleaning due to the brush renovator being used on the end of the line4 ,if the operator using the brush at the outlet ,a should use only #be ft4 of hose instead of #ajj ft4 7,fig4 #eh7 the air passing this brush will be #ge cu4 ft4 and the vacuum at the hose cock ,a will be #f4h in4 ,the vacuum at the hose cock ,b will be #h4h in4 and the vacuum at the carpet renovator 8a0 will be reduced to #c in4 with #be cu4 ft4 of air passing1 which will reduce the efficiency of the carpet renovator 8a40 ,if the brush renovator be attached to the hose cock ,b 7,fig4 #ei71 using #be ft4 of hose1 the vacuum at hose cock ,b will be #i in4 and the brush renovator will pass #he cu4 ft4 of air1 while the vacuum at hose cock ,a will now be reduced to #h4f in4 and the vacuum at the renovator will be reduced to #c in4 mercury and the air passing to #bc cu4 ft4 ,if a brush type of renovator be used at each outlet1 with #be ft4 of hose in each case and the vacuum at the separator be maintained at #aa in4 mercury the vacuum at hose cock ,b will be #g in4 and brush 8a0 will pass #gf cu4 ft4 of air while the vacuum at hose cock 8a0 will be #e in4 and brush 8b0 will pass #fc cu4 ft4 of air or a total of #add cu4 ft41 which will be in excess of the #gj cu4 ft4 per renovator recommended as the capacity of the plant in ,chapter ,,vi4 ,this will not result in any loss of efficiency if the vacuum producer be designed to handle but #adj cu4 ft4 as a maximum1 for the vacuum at the separator will then fall to a point where but #adj cu4 ft4 passes1 resulting in a decrease in the vacuum throughout the system4 ,but as only brushes are now in use there will be no loss in efficiency1 owing to the reduction in the vacuum at the brushes4 ,when #a-;in4 hose is used with a carpet renovator at the end of the pipe line connected through #ajj ft4 of hose and a brush at the hose cock ,b connected through #be ft4 of hose 7,fig4 #fj71 the worst case of the three already cited1 the vacuum at the separator being maintained at that necessary to carry #d in4 when two carpet renovators are in use1 the vacuum at the hose cock ,b will be #d4e in4 and brush 8a0 will pass #aaf cu4 ft4 of air while the vacuum at hose cock ,a will be #d4d in4 and the vacuum in renovator 8b0 will be #c4g in and will pass #bd cu4 ft4 of air4 ,these are better cleaning conditions than were obtained when #a-;in4 hose was used4 ,it will be noted that the total air passing the exhauster is now #adj cu4 ft4 and this must not be reduced or there will be a falling off in the vacuum at the carpet renovator 8b40 ,it is1 therefore1 necessary for the exhauster to be capable of handling #adj cu4 ft4 of air or #gj cu4 ft4 of air per renovator in order to do effective carpet cleaning when carpet renovators and brushes are used in conjunction4 ,when two floor brushes are used with the above arrangement of pipe and hose1 the vacuum must fall considerably or the air quantity be greatly increased4 ,however1 the reduction in vacuum will not result in serious loss in efficiency when only brushes are in use4 ,when a larger number of sweepers are used with a system of piping1 it is necessary to allow #gj cu4 ft4 of free air per sweeper in figuring the sizes of pipe to be used1 and the total loss of pressure in the piping between the outlet farthest from the vacuum producer and that nearest to same must be limited in order to prevent too wide a difference in the vacuum at the hose cock when all the sweepers for which the plant is designed are in use4 ,the author considers that this loss in pressure should not be greater than #b in4 mercury in order to give satisfactory results4 ,before the piping system can be laid out and the sizes of piping determined it is necessary to ascertain1 first1 the number of sweepers to be operated simultaneously and the number of risers necessary to properly serve these sweepers4 ,number of ,sweepers to be ,operated4--,this is determined by the character of the surfaces to be cleaned1 the amount of such surface1 and the time allowed for cleaning4 ,it has been demonstrated in actual practice that one operator can clean as high as #b1ejj sq4 ft4 of carpet when same is on floors of comparatively large areas1 and not over #a1ejj sq4 ft4 when the carpets are on small rooms2 #b1jjj sq4 ft4 is considered to be a fair average4 ,bare floors are cleaned more rapidly4 ,in school house work an ordinary class room has been cleaned in #aj minutes1 or at the rate of #g1bjj sq4 ft4 per hour1 but time is occupied in moving from one room to another and the writer considers #e1jjj sq4 ft4 per hour as rapid cleaning and #c1ejj sq4 ft4 as a fair average4 ,the time of cleaning will vary in buildings of different character and used for different purposes4 ,in office buildings the cleaning force work throughout the night or about #aj hours1 while in school houses the cleaning is done by the janitor force which has been on duty throughout the school period and the time is necessarily limited to about two or three hours after school hours1 the corridors and play rooms being cleaned during the school period and only the class rooms being cleaned after closing time4 ,let us assume1 as an example1 an office building having eight floors each #ajj ft4 #aej ft41 with a floor plan as shown in ,fig4 #fa4 ,the corridors1 stairs and elevator halls will probably be floored with marble which must be scrubbed in order to remove the stain accumulated during the day and they will not be considered in connection with a dry vacuum cleaning system4 ,the area of the floors in the offices on any floor will be approximately #aj1jjj sq4 ft4 and one floor can be cleaned by one operator in #e hours1 or two floors during the cleaning period1 so the plant must be of sufficient size to serve four sweepers simultaneously4 ,illustration3 ,,fig4 #fa4 ,,typical ,,floor ,,plan ,,of ,,office ,,building ,,illustrating ,,number ,,of ,,sweepers ,,required4 ,in a school house containing four class rooms1 where the janitor cleans the play rooms and corridors during the school period1 as can be readily done with a vacuum cleaner since there will be no dust scattered about to fill the air and render it unsanitary1 the class rooms can easily be cleaned in one hour by one operator4 ,the author considers that one sweeper capacity for each six to eight rooms is ample for a large school4 ,buildings of special construction and used for special purposes must be considered differently according to the conditions to be met1 but the size of the plant can be readily determined in each case by use of the rules already given4 ,number of ,risers to be ,installed4--,much difference of opinion exists among the various manufacturers of vacuum cleaning systems as to the maximum length of hose that should be used with a cleaning system1 and as this maximum length determines the number of risers to be installed1 some fixed standard is necessary4 ,as already stated in ,chapter ,,vi1 the author considers that this maximum should be fixed at #ge ft42 that is1 the risers should be so spaced that all parts of the floor of the building can be reached with #ge ft4 of hose4 ,where #ej ft4 is used as a maximum1 as is recommended by many manufacturers1 the number of risers would be increased1 incurring a greater cost of installation and requiring the operator to shift his hose from one inlet to another more often than would be the case where fewer inlets were used1 and more time would be required in cleaning1 with a slight reduction in the power4 ,the author does not consider that this reduction in power would be sufficient to offset the additional time required to change the hose from one inlet to another4 ,the best and quickest way to determine the number of risers necessary is to cut a piece of string to the length representing #ge ft4 on the scale of the plans1 and by running this around the plan using corridor doors for access to all rooms1 wherever possible1 locate the riser so that every point can be reached with the string4 ,in the case of the building illustrated in ,fig4 #fa four risers located as shown will be necessary4 ,size of ,risers4--,before we can determine the size of risers to be installed it is necessary to determine the probable number of sweepers that will be attached to any one riser simultaneously4 ,in the case of the building 7,fig4 #fa7 it is possible that there may be four sweepers attached to one riser and it is also possible that there may be but one1 and two sweepers to a riser is considered to be a safe assumption4 ,the author uses the following rule in determining the size of risers to use3 ,where the number of sweepers is double the number of risers1 assume that all sweepers will be on one riser simultaneously4 ,where the number of sweepers is equal to the number of risers1 assume that half the sweepers will be on one riser simultaneously4 ,where the number of sweepers is half the number of risers1 assume that one-quarter of the sweepers will be on one riser simultaneously4 ,when no lifts occur a low velocity in the riser is not objectionable and the size of the riser should be made equal to the size of the horizontal branch thereto throughout its length1 wherever this branch is not larger than #b in4 diameter4 ,when larger1 reductions in the riser can be made until #b in4 is reached when this size should be maintained throughout the remainder of its length4 ,no riser should be made less than #b in4 unless a lift is necessary4 ,before finally fixing the size of riser to be used in any case the size of the branch in the horizontal lines serving the same must be approximately determined4 ,these sizes will be dependent on the location in which it is necessary to install the vacuum producer4 ,in the case of the building 7,fig4 #fa7 the most desirable location for the vacuum producer will be in the exact center of the building4 ,with the vacuum producer centrally located the longest run from any riser will be #ee ft4 ,to this we must add3 #e ft4 for each long-turn elbow4 #aj ft4 for each short-turn elbow4 #aj ft4 for entrance to each long sweep ,y branch4 #bj ft4 for entrance to a tee branch1 except at sweeper inlets on risers1 where #aj ft4 is ample4 ,in calculating the riser friction for risers under #aej ft4 in length the whole capacity of the riser can be assumed as being connected to a point midway of its length4 ,in the eight-story building 7,fig4 #fa7 the length of the riser from basement ceiling to eighth floor will be #ajj ft4 and the length to be figured1 #ej ft4 ,the equivalent length of pipe line for any of the risers1 with the vacuum producer centrally located1 will be3 ,from entrance tee into riser #aj ft4 ,length of riser1 one-half total length #ej ft4 ,turn at base of riser #aj ft4 ,run in basement #ee ft4 ,y branch or elbow #aj ft4 ,elbow at separator #e ft4 ------ ,equivalent length #adj ft4 ,each riser is to serve two sweepers and must pass #adj cu4 ft4 of free air per minute4 ,this will give a friction loss in a #b-;in4 pipe of #b in4 mercury1 if #aj in4 mercury be maintained at the hose cock and #a-;in4 hose used2 and #a4e in4 mercury if #f in4 mercury be maintained at the hose cock and #a-;in4 hose used4 ,either of these figures are within the limits set for the maximum friction loss and #b-;in4 pipe will be the proper size for the risers and their branches in the basement4 ,the portion of the main in the basement that serves the two risers on either side of the building 7portion 8ab10 ,fig4 #fa7 must be of such size as will produce the same loss in vacuum with #bhj cu4 ft4 of air passing as the #b-;in4 pipe gives with #adj cu4 ft4 of air passing4 ,this may be determined from any table of equalization of pipes or may be obtained from the chart1 ,fig4 #dh1 in the following manner3 ,find the intersection of the horizontal line 8#adj0 with the diagonal representing a #b-;in4 pipe and pass on the nearest vertical to its intersection with the horizontal line 8#bhj40 ,the diagonal inclined toward the left passing nearest this intersection will be the pipe size required4 ,in this case a #c-;in4 pipe will give a slightly greater friction and will be sufficient4 ,unfortunately1 it is rarely possible to locate the vacuum producer in as favorable a point as that given in the illustration1 but an effort should always be made to select a location as nearly central to all risers as possible4 ,the basements of modern office buildings are generally crowded and the space assigned to the mechanical equipment is limited and owing to the necessity of ventilation1 the vacuum producer is generally located near the outside of the building4 ,probably the best location that could be obtained in this case would be at 8d0 7,fig4 #fb74 ,the length of piping to risers #a and #b would now be the same as that to all risers in case of ,fig4 #fa1 but the distance to risers #c and #d will be increased #ej ft4 ,it will be possible to increase the size of the pipe line 8bd0 to the maximum size to serve four sweepers1 or #c in41 the risers and their branches to remain #b in4 ,the total friction loss to risers #a and #b will now be3 ,entrance to tee in risers1 #aj ft4 plus #ej ft4 #fj ft4 ,turn at base of riser1 #aj ft41 branch from 8c0 to riser #cb ft4 #db ft4 ,entrance to tee in main #bj ft4 ------- ,total equivalent length of #b-;in4 pipe #abb ft4 ,when #a-;in4 hose is used the density of the air entering the #b-;in4 pipe is equivalent to a vacuum of #aj in4 mercury and the friction loss in the #b-;in4 pipe will be #a4i in4 mercury4 ,when #a-;in4 hose is used1 the density of the air entering the pipe will be equivalent to a vacuum of #f-;in4 mercury and the friction loss in the #b-;in4 pipe will be #a4cb in4 mercury4 ,illustration3 ,,fig4 #fb4 ,,elevation ,,of ,,layout ,,for ,,office ,,building1 ,,showing ,,best ,,location 7,,at ,d7 ,,for ,,vacuum ,,producer4 ,the density of the air entering the #c-;in4 pipe1 8bd10 will be equivalent to a vacuum of #aa4i in4 mercury when #a-;in4 hose is used1 and to #g4cb in4 mercury when #a-;in4 hose is used4 ,the friction loss in the #c-;in4 pipe will be #j4ca and #j4bc in4 mercury1 respectively4 ,total friction loss to inlets on risers #a and #b will be #b4ba in4 with #a-;in4 hose in use1 and #a4ee in4 with #a-;in4 hose4 ,to obtain the friction loss to inlets on risers #c and #d the friction loss in the pipe 8bc0 must be added to the above figures4 ,with #ej ft4 of #c-;in4 pipe carrying #bhj cu4 ft4 free air the friction loss is #j4f in4 when the vacuum in the pipe is #ab in4 and #j4d when the vacuum in the pipe is #h in4 ,the total loss of vacuum to inlets on risers #c and #d will be #b4ia in4 if #a-;in4 hose is used and #a4ie in4 if #a-;in4 hose is used4 ,in this case1 the total loss from inlet to vacuum producer is approximately equal to the maximum variation of vacuum permitted at sweeper outlets when #a-;in4 hose is used1 but is greater than when #a-;in4 hose is used4 ,however1 it is the variation in vacuum at the hose cock farthest from and that nearest to the vacuum producer that fixes the maximum variation allowable4 ,in this case it will be the difference in vacuum between an inlet on riser #a or #b and a similar inlet on riser #c or #d4 ,the difference in vacuum at the bases of these risers will be the friction loss in the pipe 8bc10 and the total difference in friction in the risers will occur when one sweeper is attached to the lowest inlet on one riser1 and one sweeper on the eighth and one on the seventh floor on the other riser4 ,the friction loss in the riser having the two sweepers attached to its upper inlets will be3 #ae ft4 of #b-;in4 pipe from seventh to eighth floors1 #gj cu4 ft4 of free air per minute1 or #j4jea in4 with a density equivalent to #f-;in4 vacuum1 and #j4jge in4 with a density equivalent to #aj-;in4 vacuum4 #he ft4 of #b-;in4 pipe from first to seventh floors1 #adj cu4 ft4 free air per minute1 or #j4be in4 with a density equivalent to #f-;in4 vacuum1 and #j4db in4 with a density equivalent to #aj-;in4 vacuum4 ,the total difference in vacuum at the hose cocks will be3 #j4jea #j4be #j4d #j4g in4 with #f-;in4 vacuum at the hose cock4 #j4jge #j4db #j4f #a4ae in4 with #aj-;in4 vacuum at the hose cock4 ,either of these values are well within the maximum variation4 ,it is1 therefore1 evident that when the vacuum producer cannot be centrally located that a piping system which will give the most nearly equal length of pipe to each riser will yield the best results4 ,a vacuum cleaning system for serving a passenger car storage yard will best illustrate the effect of long lines of piping4 ,a typical yard having #h tracks1 each of sufficient length to accommodate #aj cars1 is shown in ,fig4 #fc4 ,the vacuum producer in this case is located at the side of the yard at one end1 which is not an unusual condition4 ,illustration3 ,,fig4 #fc4 ,,vacuum ,,cleaning ,,layout ,,for ,a ,,passenger ,,car ,,storage ,,yard4 ,the capacity of this yard will be #hj cars which must generally be cleaned between the hours of midnight and #f ,a4 ,m41 or a period of #f hours for cleaning4 ,it will require one operator approximately #bj minutes to thoroughly clean the floor of one car1 on account of the difficulty in getting under and around the seat legs4 ,in addition to this1 it is also necessary to clean the upholstery of the seats and their backs1 which will require approximately #be minutes more or #de minutes for one operator to thoroughly clean one car4 ,therefore1 one operator can clean #h cars during the cleaning period and a ten-sweeper plant will be necessary to serve the yard4 ,one lateral cleaning pipe must be run between every pair of tracks or four laterals in all to properly reach all cars without running the hose across tracks where it might be cut in two by the shifting of trains4 ,outlets should be spaced two car lengths apart in order to bring an outlet opposite the end of every second car4 ,this will make it possible to bring the hose in through the end of the car at the door opening and clean the entire car from one end which can be done by using #ajj ft4 of hose4 ,the use of double the number of outlets and #ej ft4 of hose would require two attachments of the hose to clean one car resulting in a loss of time in cleaning and is not recommended4 ,in this case1 #ajj ft4 of hose would be the shortest length that would be likely to be used and #fj cu4 ft4 of free air would be the maximum to be allowed for when using #a-;in4 hose4 ,the simplest layout for a piping system to serve this yard would be that shown in ,fig4 #fc4 ,when the entire yard is filled with cars and the entire force of ten operators is started to clean them it would be possible to so divide them that not over three operators would be working on any one lateral and this condition will be assumed to exist4 ,the maximum size for the laterals between the tracks will be that for three sweepers1 or #c in41 and it will not be safe to use this size beyond the second inlet from the manifold1 from which point to the end of the lateral it must be made #b in41 the maximum size for either one or two sweepers4 ,the total loss of pressure due to friction from the inlet at x 7,fig4 #fc7 to the separator can be readily calculated from the chart 7,fig4 #ef7 as follows3 ,,table #bj4 ,,pressure ,,losses ,,from ,,inlet ,,to ,,separator ,,in ,,system ,,for ,,cleaning ,,railroad ,,cars4 ---------------------------------------- -------------------- ,average ,friction ,final ,cubic ,ft4,equivalent ,size of ,vacuum1 ,loss1 ,vacuum1 ,section ,free ,air ,length1 ,pipe1 ,ins4 ,ins4 ,ins4 of ,pipe4 per min4 feet4 ,in4 ,diam4,mercury4,mercury4,mercury4 ---------------------------------------- -------------------- x--#e #fj #aej #b #f #j4ce #f4ce #e--d #abj #adj #b #g #a4ce #g4gj #d--b #ahj #bhj #b #aa #g4j #ad4gj #b--w #ahj #aij #c #af #d4j #ah4gj w--u #cfj #bj #e #ai #j4i #ai4fj u--s #dhj #bj #f #bj #j4e #bj4aj s--sep #fjj #bj #f #bj #j4d #bj4ej ---------------------------------------- -------------------- ,this loss will be the maximum that is possible under any condition as it is computed with three sweepers working on the three most remote inlets on laterals 8xy0 and 8vw0 and with two sweepers on laterals 8tu0 and 8rs40 ,the pipes are the largest which will give a velocity of #dj ft4 per second with the full load and at the density which will actually exist in the pipe lines with the vacuum maintained at the separator of #bj in4 mercury in all cases1 except the pipe from 8s0 to separator4 ,there the size was maintained at #f in41 as it was not considered advisable to increase this on account of the reduced velocity which would occur when less than the total number of sweepers might be working4 ,as bare floor brushes will be used for cleaning coaches it is not considered advisable to reduce the air quantity below that required by such renovators4 ,however1 when carpet renovators are used in ,pullman cars and upholstery renovators are used on the cushions of both coaches and ,pullmans1 the air quantity will be reduced4 ,this condition may exist at any time1 also one of these carpet or upholstery renovators may be in use on one of the inlets most remote from the separator at the same time that nine floor brushes are in use on the remaining outlets4 ,in that case a vacuum at the separator of less than #bj in4 would result in a decrease in the vacuum at the inlet to which this renovator was attached4 ,the vacuum at the separator must1 therefore1 be maintained at the point stated4 ,with such a vacuum there will be variation in the vacuum at the hose cocks of from #f in4 to #bj in4 or seven times the maximum allowable variation in vacuum at the hose cocks4 ,if #a-;in4 hose be used1 the maximum air quantities will be #dj cu4 ft4 per sweeper4 ,if we start with a vacuum at the inlet 8x0 of #aj-;in4 mercury1 the vacuum at the separator will again be #bj in4 and we now have a variation of #aj in4 between the nearest and most remote inlet from the separator1 or five times the maximum allowed4 ,either of these conditions is practically prohibitive1 due to3 #a4 ,the excessive power consumption at the separator4 #ej ,h4 ,p4 in case #a-;in4 hose is used1 and #cc ,h4 ,p4 in case #a-;in4 hose is used4 #b4 ,the excessive capacity of the exhauster in order to handle the air at such low density1 a displacement of #a1hjj cu4 ft4 being necessary in case #a-;in4 hose is used and #a1bjj cu4 ft4 in case #a-;in hose is used4 #c4 ,the great variation in the vacuum at the hose cocks which will admit the passage of so much more air through a brush renovator on an outlet close to the separator as to render useless the calculations already made1 or the high vacuum at the carpet or upholstery renovators would render their operation practically impossible4 ,illustration3 ,,fig4 #fd4 ,,arrangement ,,of ,,piping ,,recommended ,,as ,,best ,,for ,,passenger ,,car ,,storage ,,yard4 ,such a layout must be at once dismissed as impractical1 and some other arrangement must be adapted4 ,the arrangement of piping shown in ,fig4 #fd is considered by the author to be the best that can be devised for this case4 ,with this arrangement the vacuum at the separator must be maintained at #aa4ej in4 mercury to insure a vacuum of #f in4 mercury at the outlet 8x0 under the most unfavorable conditions1 and the maximum variation in vacuum at the inlets will be #c4de in4 mercury when #a-;in4 hose is used4 ,this will give a maximum vacuum under a carpet renovator of #g in4 mercury with #cg cu4 ft4 of air passing and will permit #gj cu4 ft4 of free air per minute to pass a brush renovator when operating with #ajj ft4 of hose attached to the inlet at which the highest vacuum is maintained4 ,both of these conditions will permit satisfactory operation and the increased air quantities will not seriously affect the calculations already made4 ,the maximum horse power required at the separator will now be #bj4e as against over #ej in the case of the piping arrangement shown in ,fig4 #fc1 and will require an exhauster having a displacement of #iej cu4 ft4 instead of #a1hjj cu4 ft4 required with the former layout4 ,if #a-;in4 hose is used and #aj in4 mercury maintained at the outlet 8x0 under the same conditions as before1 the vacuum at the separator will be #ad4ej in4 and the maximum variation in the vacuum at the inlets will be #c in41 which will give a maximum vacuum under a carpet renovator of #f in4 mercury with #cb cu4 ft4 of air passing and will permit the passage of #de cu4 ft4 of free air through a brush renovator when operated at the end of #ajj ft4 of hose attached to the outlet at which the highest vacuum is maintained4 ,this is a more uniform result1 than was noted when #a-;in4 hose was used4 ,the maximum horse power which will be required at the separator will now be #ah4f and the maximum displacement in the exhauster will be #gdj cu4 ft4 ,it is1 therefore1 evident that1 where very long runs of piping are necessary and where #ajj ft4 of hose will always be necessary1 the use of #a-;in4 hose will require less power and a smaller displacement exhauster than would be required with #a-;in4 hose1 without affecting the efficiency of the cleaning operations1 and at the same time rendering the operation of the renovators on extreme ends of the system more uniform4 ,the example cited in ,figs4 #fc and #fd is not by any means an extreme case to be met in cleaning systems for car yards1 and the larger the system the greater will be the economy obtained with #a-;in4 hose4 ,such conditions1 however1 are confined almost entirely to layouts of this character and will seldom be met in layouts within any single building4 ,this is fortunate1 as the train cleaning is practically the only place where the use of #ajj ft4 of hose can be assured at all times4 ,very tall buildings offer a similar condition although the laterals are now vertical and can be kept large enough to sufficiently reduce the friction without danger of deposit of dirt in them1 and the horizontal branches will be short and also large enough to keep the friction within reasonable limits without danger of deposit of dust4 ,where large areas within one or a group of buildings must be served by one cleaning system1 better results can often be obtained by installing the dust separator at or near the center of the system of risers instead of close to the vacuum producer1 as indicated in ,fig4 #fe4 ,when this is done1 the pipe leading from the separator to the vacuum producer carries only clean air and can be made as large as desired and the friction loss reduced1 resulting in a considerable reduction in the power required to operate the system4 ,illustration3 ,,fig4 #fe4 ,,good ,,location ,,for ,,dust ,,separator ,,where ,,large ,,areas ,,are ,,served ,,by ,,one ,,cleaning ,,system4 ,where the system becomes still larger1 two or more separators located at centers of groups of risers can be used and clean air pipes of any desired size run to the vacuum producer 7,fig4 #ff74 ,when more than one separator is used care should be exercised in proportioning the pipe lines from the separators to the vacuum producer so as to have the friction loss from the vacuum producer to each separator the same in order to give uniform results at all inlets4 ,this loss should also be kept as low as possible in order to prevent a high vacuum in a separator serving a portion of the system on which few sweepers are in operation4 ,if low friction losses in the clean air pipe will require larger pipes than it is practical or economical to install1 pressure reducing valves might be located in the clean air pipes near the separators to so regulate the vacuum at the separators and insure uniform results4 ,a system of this kind might serve several premises and the air used by each be metered and the service sold much the same as heat and electricity4 ,however1 the power required to operate the system would be greater than that needed to operate a similar number of sweepers by individual plants owing to the higher vacuum required to overcome the friction in the trunk mains4 ,this would be offset by the use of larger units and the possibility of operating them at full load at nearly all times4 ,a system of this kind was contemplated in ,milwaukee some seven years ago1 but was never installed4 ,illustration3 ,,fig4 #ff4 ,,location ,,of ,,separators ,,at ,,centers ,,of ,,groups ,,of ,,risers ,,for ,,large ,,systems4 ,the question of pipe friction in connection with the design of vacuum cleaning systems requires careful consideration1 much more than it ever received in the early days of the art and a great deal more than it sometimes receives at the present time4 ,,chapter ,,viii4 ,,separators4 ,the appliances which remove the dust from the air current which has carried it through the hose and pipe lines1 in order to prevent damage to the vacuum producer1 play an important part in the make-up of a vacuum cleaning system4 ,classification of ,separators4--,separators may be divided into two classes according to their use3 #a4 ,partial separators1 which must be used in conjunction with another separator in order to effect a complete removal of the dust from the air4 ,these separators are again divided into two sub-classes1 i4 e41 primary1 or those removing the heavy particles of dust and dirt only1 and secondary1 or those removing the finer particles of dirt which have passed through the primary separator4 #b4 ,complete separators1 or those in which the removal of both the heavy and the finer particles of dust is effected in a single separator4 ,separators may also be classified1 according to the method employed in effecting the separation1 into dry separators in which all operations are effected without the use of liquid1 and wet separators in which water is employed in the removal of the dust4 ,primary ,separators4--,primary separators are nearly always operated as dry separators and depend largely on centrifugal force to effect the separation4 ,the first type of primary separator used by the ,vacuum ,cleaner ,company is illustrated in ,fig4 #fg4 ,this consists of a cylindrical tank1 with hopper bottom1 containing an inner cylinder fixed to the top head4 ,the dust-laden air enters the outer cylinder near the top on a tangent to the cylinder4 ,the centrifugal action set up by the air striking the curved surface of the outer cylinder tends to keep the heavy dirt near the outside of same1 and as it falls towards the bottom the velocity is reduced and its ability to carry the dust is lost4 ,when the air passes below the inner cylinder the velocity is almost entirely destroyed and all but the very lightest of the dust particles fall to the bottom1 while the air and the light dust particles find their way out of the separator through the opening in the center at the top4 ,illustration3 ,,fig4 #fg4 ,,early ,,type ,,of ,,primary ,,separator ,,used ,,by ,,vacuum ,,cleaner ,,company4 ,illustration3 ,,fig4 #fh4 ,,primary ,,separator ,,used ,,by ,,the ,,sanitary ,,devices ,,manufacturing ,,company4 ,the primary separator used by the ,sanitary ,devices ,manufacturing ,company is illustrated in ,fig4 #fh4 ,the inner centrifugal cylinder is omitted and the air enters through an elbow in the top of the separator1 near its outer extremity1 which is turned at such an angle that the air is given a whirling motion resulting in the dust being separated much the same as in the case of the ,vacuum ,cleaner ,company's apparatus4 ,either of these separators will remove from #ie to #ih of the dirt that ordinarily comes to them through the pipe lines and are about equally efficient4 ,illustration3 ,,fig4 #fi4 ,,primary ,,separator ,,used ,,by ,,the ,,general ,,compressed ,,air ,,and ,,vacuum ,,cleaning ,,company4 ,illustration3 ,,fig4 #gj4 ,,primary ,,separator ,,made ,,by ,,the ,,blaisdell ,,engineering ,,company4 ,the separator illustrated in ,fig4 #fi was used by the ,general ,compressed ,air and ,vacuum ,cleaning ,company4 ,the entering air is led to the center near the bottom and is then released through two branches curved to give the air a whirling motion4 ,the clean air is removed from the center of the separator near the top4 ,this separator is not as effective in its removal of dirt as either of the former types1 owing to the entering air being introduced near the bottom4 ,this tends to keep the air and the dust in the bottom of the separator continually stirred up1 also the curved inlets give the air more of a radial than a tangential motion and there is less separation due to centrifugal action4 ,the separator illustrated in ,fig4 #gj is made by the ,blaisdell ,engineering ,company4 ,in this separator the inner centrifugal cylinder of the ,vacuum ,cleaner ,company's separator is replaced by a spiral extending nearly to the outlet in the center of the top4 ,this arrangement tends to prevent the reduction in the air velocity and to limit its effectiveness in the removal of dust4 ,separators similar to the ,sanitary separator have been manufactured by many firms producing vacuum cleaning systems4 ,these all differ somewhat in details of construction but the principle involved1 i4 e41 centrifugal force and reduction in air velocity1 is the same in all cases4 ,with vacuum producers in which there are no close clearances or rubbing contacts1 these are the only separators used4 ,the finer particles of dust passing these separators are carried harmlessly through the vacuum producer and through the exhaust to the outer atmosphere or to the chimney or other flue where they are effectively sterilized4 ,secondary ,separators4--,with vacuum producers having close clearances or rubbing parts in contact with each other and the air exhausted1 further separation of the finer dust particles is necessary4 ,to accomplish this1 secondary separators are used4 ,all of the early systems used a wet separator as a secondary separator4 ,that used by the ,vacuum ,cleaner ,company is illustrated in ,fig4 #ga4 ,it consists of a cylindrical tank partially filled with water1 with a diaphragm perforated in the central portion and fixed in place below the water line1 and an inverted frustrum of a cone placed just above the water line4 ,the air enters the separator below the water line and passes up through the water in the form of small bubbles which are broken up into still smaller bubbles on passing through the perforations in the diaphragm4 ,this action is very essential to the thorough cleansing of the air1 as large bubbles of air may contain entrapped dust which will pass through the water and out into the vacuum producer4 ,the inverted frustrum of a cone is intended to prevent any entrained water passing out of the separator with the air4 ,this separator has always given satisfactory results when used in connection with reciprocating pumps4 ,the separator illustrated in ,fig4 #gb was manufactured by the ,general ,compressed ,air and ,vacuum ,cleaning ,company4 ,the air enters the separator through the pipe curved downward and escapes at the center below the water line4 ,it then rises in the form of bubbles and most of it strikes the under side of the ribbed aluminum disc 8a10 which is intended to float on the surface of the water1 and passes along the ribbed under surface of this disc1 escaping into the upper part of the separator around the edge4 ,illustration3 ,,fig4 #ga4 ,,secondary ,,separator ,,used ,,by ,,the ,,vacuum ,,cleaner ,,company4 ,illustration3 ,,fig4 #gb4 ,,secondary ,,separator ,,used ,,by ,,the ,,general ,,compressed ,,air ,,and ,,vacuum ,,cleaning ,,company4 ,the clean air passes out of the top of the separator to the vacuum producer4 ,the successful operation of this separator is dependent on the freedom of motion of the disc 8a10 which will always keep it on the surface of the water1 and on all of the air passing up through the water under the disc4 ,should the disc become caught on the supporting pipe the violent agitation of the water1 which occurs when the system is in operation1 will cause the disc to be left high and dry above the water at times1 and submerged at other times4 ,when this disc is above the water line it will not break up any of the large bubbles4 ,also1 when there is a large quantity of air passing through the separator1 there is great likelihood that considerable of the air bubbles will pass up through the water entirely outside of the disc and these bubbles will not be broken up4 ,this separator has given somewhat unsatisfactory results in some installations tested by the author4 ,illustration3 ,,fig4 #gc4 ,,secondary ,,separator ,,used ,,by ,,the ,,sanitary ,,devices ,,manufacturing ,,company4 ,illustration3 ,,fig4 #gd4 ,,type ,,of ,,dry ,,separator ,,used ,,as ,,secondary ,,separator4 ,the separator used by the ,sanitary ,devices ,manufacturing ,company differs from those already described in that the air and water are mixed before they enter the separator and the air comes into the separator above the water line4 ,the air enters the pipe 8a0 7,fig4 #gc7 and passes to the aspirator 8b10 which is connected to the separator by the pipe 8d0 below the water line and the pipe 8e0 above the water line4 ,the excess of vacuum in the separator draws the water out of the aspirator and its pipe connections until the water line in this pipe is lowered below the top of the horizontal portion of the piping1 when the air bubbles up through the demonstrator glass 8c0 and passes into the separator through the pipe 8e40 ,the filling of the vertical pipe leading to 8c0 with air causes the static head of the water in the separator to produce a flow of water through the pipe 8d0 into the aspirator 8b40 ,this is formed in the shape of a nozzle and the water enters in the form of a spray and thoroughly mixes with the air4 ,the cleansing action of this water spray has been found to be very effective in removal of all fine dust and this separator has been found to be the most effective wet separator ever produced4 ,while the wet separator when properly designed will effectively remove the finest of dust1 greasy soot will not emulsify with the water and its removal is practically impossible4 ,fortunately1 this form of material in the finely-divided condition in which it passes the primary separator is not gritty and does not produce injurious effect on the vacuum producer4 ,the wet separator is also at a disadvantage in that there is a loss of vacuum in passing through same equal to the head of water that is carried between the inlet and the surface of the water4 ,this generally amounts to nearly #b in4 mercury4 ,means must be provided to observe the height of the water in the wet separator4 ,for this purpose a glass window in the side of the separator has been found to be the most effective4 ,the use of an ordinary gauge glass such as is used on boilers has been tried1 but it has been found that they readily become so clouded by the action of the muddy water as to render them useless while the constant agitation of the water against the window when the system is in operation tends to keep the glass clean4 ,dry separators have been used for secondary separators to a limited extent4 ,all of these contained a bag made of canvas or some other fabric4 ,the separator illustrated in ,fig4 #gd contains a bag made of drilling which is slightly smaller than the inner diameter of the cylindrical casing of the separator4 ,the air enters the inside of the bag1 inflating it1 and passes through the bag and out through the opening in one side of the casing4 ,a wire guard is placed over this opening to prevent the bag being drawn against the opening and thus rendering only a small portion of it effective4 ,these bags offer very little resistance to the passage of the air when they are clean but they soon become filled with dust and produce an increased resistance which1 if neglected1 may result in so great a difference in pressure as to hinder the action of the system and result in the rupture of the bag1 letting the dust into the vacuum producer4 ,some trouble has been experienced in finding a suitable material through which the dust will not pass4 ,hush cloth1 such as used on dining tables1 has been found to be the best material for this purpose4 ,better results are obtained by passing the air from the outside of the bag towards the inside than when the air is passed as indicated in ,fig4 #gd4 ,when this arrangement is adopted1 it is necessary to stretch the bag over a metal screen or frame in order to prevent collapse4 ,complete ,separators4--,complete separators are of two classes1 i4 e41 dry and wet4 ,the first complete separator that the author has knowledge of was used by the ,vacuum ,cleaner ,company1 in the form of a cylindrical tank and contained centrifugal cylinder and also a perforated plate4 ,it was practically a combination of the separators indicated in ,figs4 #fg and #ga4 ,this separator was installed in connection with a small rotary pump and mounted on a truck4 ,it worked very well until it became filled with dirt when1 in one case1 the entire contents were ejected into an apartment in which it was being used4 ,this separator was then rebuilt in the form shown in ,fig4 #ge1 the bag being made of hush cloth stretched over a wire screen4 ,the air enters the cylinder tangentially and much of the separation is accomplished by centrifugal force1 the remainder of the dust being removed as the air passes through the bag4 ,this separator was successfully used as long as this company continued to manufacture such apparatus4 ,another form of complete separator quite similar to that above described has recently been brought out by the ,electric ,renovator ,manufacturing ,company and is shown in section in ,fig4 #gf4 ,the air enters this separator tangentially below the line of the dust bag1 which is made of muslin folded back and forward over a set of concentric cylinders thus giving a large area for the passage of the air4 ,being entirely above the line of the entering air1 none of the heavy dirt strikes the bag and what dirt is caught on the bag is on the lower side of same and is shaken off every time the bag is agitated4 ,this agitation occurs every time there is any change in the volume of air passing the separator1 and when these separators are used in connection with fan type of exhausters there is a constant surging whenever the exhauster is operated with a small volume of air passing4 ,this tends to keep the bag clean automatically4 ,illustration3 ,,fig4 #ge4 ,,form ,,of ,,complete ,,separator ,,used ,,by ,,the ,,vacuum ,,cleaner ,,company4 ,the separator illustrated in ,fig4 #gg is manufactured by the ,american ,radiator ,company4 ,the air enters this apparatus through the pipe in the center and passes directly down to the bottom1 the velocity being gradually reduced due to the expansion of the air as it passes down the cone-shaped inlet1 the heavy dirt falling to the bottom4 ,the air then passes up along the inner surface of the cylindrical shell and thence through the bag1 which is stretched over a screen1 to the outlet4 ,in this separator we see the first case in which centrifugal action is not utilized in separating the heavy dust1 the makers evidently considering the reduction of air velocity and the action of gravitation to be ample4 ,this bag is arranged to permit the air passage from the outside towards the inside and it is tapered to allow the dirt to fall off4 ,the vacuum gauge is connected to the inner and outer sides of the bag by means of a three-way cock to permit of measuring the difference in vacuum between the inside and outside of the bag to determine when the bag is in need of cleaning1 which is accomplished by a reversal of the air current through the bag4 ,this is quite necessary in order to keep the separator always in an efficient condition4 ,illustration3 ,,fig4 #gf4 ,,complete ,,separator ,,brought ,,out ,,by ,,the ,,electric ,,renovator ,,manufacturing ,,company4 ,illustration3 ,,fig4 #gg4 ,,complete ,,separator ,,made ,,by ,,the ,,american ,,radiator ,,company4 ,a separator was devised by the ,sanitary ,devices ,manufacturing ,company in which the bag was held extended by a wire ring having a weighted rod passing out through the top of the separator attached thereto4 ,when the bag became clogged the difference in pressure on the two sides would result in a tendency of the bag to collapse and the rod would be raised up out of the separator1 indicating that cleaning was necessary1 which could be easily accomplished by drawing the rod up and down a few times thus shaking the dust off the bag4 ,this separator never came into general use1 although its arrangement was ingenious and should have been easy to operate4 ,the great difficulty with all bags which must be cleaned periodically is that they are almost universally neglected even when there is a visual indicator to show the accumulation of dirt1 and when it becomes necessary to manipulate a three-way cock in order to ascertain when this cleaning must be done it will seldom if ever be attended to4 ,a bag that will clean itself1 such as the ,capitol ,invincible1 is shown in ,fig4 #gf4 ,the separator used by one manufacturer consists of a simple cylindrical tank into which the air is blown tangentially1 with a screen near the top1 the whole forming a base for the vacuum producer4 ,this separator does not remove any but the heaviest dirt and is suitable for use only with a vacuum producer having very large clearances and in locations where the discharge of considerable dirt into the atmosphere is not objectionable4 ,total ,wet ,separator4--,the only total wet separator which is in commercial use is manufactured by the ,american ,rotary ,valve ,company4 ,this separator is contained in the base of the vacuum producer and is provided with a screen near the point of entrance of the dust-laden air1 which screen is cleaned by a mechanically-driven bristle brush4 ,when the water in the separator becomes foul1 the contents of the separator are discharged direct to the sewer by means of compressed air4 ,if this separator receives proper attention it makes the most sanitary arrangement that has been introduced in the vacuum cleaning line to date4 ,however1 the separator should be emptied at frequent intervals or the volume of solid matter contained in the same will become so great that there will not be enough water present to flush the sewer and stoppage is likely4 ,these separators are often neglected until the contents become of the consistency of mortar or molasses which is not a fit substance to discharge into a sewerage system4 ,there is still another form of apparatus used in connection with vacuum cleaning systems which should be called an emulsifier rather than a separator4 ,that is the type used with the ,rotrex and the ,palm systems4 ,the dust is mixed with water when it first enters the pump chamber1 a screen being used to remove the lint and larger particles of dirt and then the mud produced by the combination of the dust and water is passed through the pump along with the air4 ,the air and muddy water are separated on the discharge side of the vacuum producer4 ,in many cases where the exhaust pipe is long1 there is considerable back pressure on the discharge which is often sufficient to force the seals in traps on the sewerage system1 allowing sewer gas to be discharged into the building in which the cleaning system is installed4 ,no means are provided for automatically cleaning the screen used in these appliances and the author knows of cases where the screen has become so completely clogged with lint that its removal from the machine was necessary in order to render the operation of the cleaning tools possible4 ,when dry separators are used1 the manual removal of the dry dirt accumulated is necessary and is an objectionable as well as unsanitary operation4 ,the author considers that the ideal arrangement of separator would be one in which the dirt can all be emulsified with water and retained in the separator1 only the air passing through the vacuum producer1 and in which the contents of the separator would be discharged automatically to the sewer when the density of this mixture becomes as heavy as will readily run through the sewer4 ,this discharge should be of sufficient volume to completely fill an ordinary house sewer in order to insure a thorough flushing of the drain1 and should be discharged into the sewer under atmospheric pressure in order to guard against the forcing of water seals in any of the plumbing fixtures4 ,illustration3 ,,fig4 #gg;a4 ,,interior ,,construction ,,of ,,dunn ,,vacuum ,,cleaning ,,machine4 ,a separator of this type has recently been patented by ,e4 ,d4 ,dunn1 originator of the ,dunn ,locke system4 ,it is illustrated in ,fig4 #gg;a4 ,the action of the separator is as follows3 ,after starting the motor and turning on a small quantity of water1 a vacuum is produced in one tank and through a system of piping to the cleaning implement in use4 ,the dust and dirt collected by the implement is saturated as it approaches the plant and in this saturated condition enters the bottom of a body of water in the tank4 ,when the accumulating dirt and water reach a certain level a valve is automatically operated which closes the tank's communication with the vacuum pump and allows its contents to flow off to the sewer by gravity4 ,the mechanism for operating the valve is rather unique and includes a float which1 on rising with the water1 makes a positive electrical contact1 as shown in the figure4 ,in this illustration one tank is about to discharge and the other tank is about to become operative4 ,the electrical contact causes the core of the magnet at ,o to rise1 making the lever1 ,k1 turn over1 which action opens one valve and closes the other4 ,in this way the tanks alternately partly fill and empty their collections of water and sweepings4 ,this system has not as yet been in commercial use for a sufficient length of time to insure its successful operation1 and the author does not consider the passing of dirt and water through ordinary check valves to be commercially possible without rendering these checks inoperative4 ,check valves have been used where partial wet and dry separators are operated in tandem to prevent drawing water into the dry separator1 in the event of the plant being shut down with all inlets on the pipe line closed4 ,in such a case1 the leakage through the pump into the wet separator may raise the pressure in this separator faster than leakage on the pipe line raises the pressure in the dry separator4 ,this is accomplished by providing a small connection between the upper part of the two separators1 fitted with a check valve opening towards the dry separator4 ,when the vacuum producer is in operation1 the vacuum in the wet separator is approximately #b in4 greater than that in the dry and the check is held closed4 ,when the vacuum producer is stopped and the vacuum in the wet separator falls faster than in the dry separator1 this check opens and clean air passes from the wet to the dry separator4 ,when operating under these conditions1 the action of the check valve is satisfactory4 ,however1 the author has known of cases where the check leaked and when this happened the check was immediately clogged by the dust-laden air from the dry separator4 ,,chapter ,,ix4 ,,vacuum ,,producers4 ,the next portion of the cleaning system is that which produces the motion of the air through the system and that to which the motive power is applied1 namely1 the vacuum producer4 ,types of ,vacuum ,producers4--,vacuum producers can be divided into general classes3 #a4 ,displacement type1 in which a constant volume of air is displaced during each complete cycle of operations of the machine1 and #b4 ,centrifugal type1 in which the volume of air passing the producer during each complete cycle of operations varies with the resistance to the passage of such air through the system4 ,displacement ,type4--,under this head the piston and rotary pumps are classed1 and they are subdivided according to construction into reciprocating and rotary1 valved and valveless1 air cooled and water cooled4 ,centrifugal ,type4--,under this head the fan type of vacuum producers are classed4 ,they may be divided1 according to construction1 into single stage and multi-stage1 horizontal and vertical4 ,power ,required to ,produce ,vacuum4--,in order to ascertain the efficiency of the various types of exhausters to be discussed in this chapter it is necessary to ascertain the actual power necessary to move one cubic foot of free air at any degree of vacuum4 ,as nearly all machines tested by the author were driven by electric motors and the power was1 therefore1 indicated in watts1 the curve ,c-,d in ,fig4 #gh showing the actual power necessary to exhaust one cubic foot of free air at the vacuum noted in the lower margin1 assuming no clearance and adiabatic compression1 is used as a basis for calculation of efficiency4 ,this shows that to produce a vacuum of #h in4 mercury there will be required an expenditure of #af watts for each cubic foot of free air exhausted1 and to produce a vacuum of #ab in4 mercury will require an expenditure of #bg watts4 ,if these quantities be divided by the efficiency of the machine the actual power required will be determined4 ,illustration3 ,,fig4 #gh4 ,,power ,,consumption ,,and ,,efficiency ,,of ,,air ,,compressor ,,used ,,as ,a ,,vacuum ,,pump4 ,reciprocating ,pumps4--,the reciprocating pump was used on the majority of the earlier vacuum cleaning systems4 ,the most common form in early use was a commercial air compressor which was used as a vacuum pump without any change in its construction4 ,it was usually fitted with mechanically-operated induction and poppet type of eduction valves of heavy pattern1 fitted with cushions of the dash pot principle1 the same as are used on air compressors working against terminal pressures as high as #ajj lbs4 per square inch4 ,the cylinders were water jacketed to remove the heat of high compression4 ,the valves in these compressors were heavy and required considerable pressure to open them and the friction of the valve gear and other moving parts1 which were made heavy enough to withstand the strains of high compression1 was excessively high for a machine where the compression did not exceed #h or #i lbs4 per square inch4 ,their efficiency1 therefore1 is lower under actual operating conditions than if they were working against pressures for which they were designed4 ,a curve of the power consumption of a #ad-;in4 #h-;in4 ,clayton compressor is shown on ,fig4 #gh1 the abscissae being the vacuum in inches of mercury and the ordinates of curve 8,,ab0 the watts required to exhaust one cubic foot of free air4 ,curve 8cd0 represents the theoretical watts required to do the same work4 ,these compressors were used in connection with systems operating with #a-;in4 hose and the vacuum usually carried was #ae in4 mercury4 ,they require approximately #gg watts per cubic foot of free air at this vacuum and the efficiency1 shown in curve 8ce0 7,fig4 #gh7 is #df4 ,illustration3 ,,fig4 #gi4 ,,modification ,,of ,,reciprocating ,,pump ,,made ,,by ,,the ,,sanitary ,,devices ,,manufacturing ,,company4 ,were this compressor used in connection with a system operating through #a-;in4 hose and a vacuum of #h in4 mercury maintained1 the efficiency would drop to #ca4 ,a modification of the reciprocating pump was manufactured by the ,sanitary ,devices ,manufacturing ,company in which light-weight poppet valves placed in the heads of the cylinder were used1 as indicated in ,fig4 #gi4 ,curves of the watts per cubic foot and efficiency of this type of compressor are shown in ,fig4 #hj4 ,it will be noted that this compressor shows a better efficiency than the air compressor at all degrees of vacuum and it is the best reciprocating pump that the writer has ever tested4 ,this pump was made for several years without water jacket and no trouble was ever experienced with overheating4 ,however1 owing to the commercial air compressors being jacketed1 the makers using same made this a talking point and this company was obliged to jacket its pumps4 ,illustration3 ,,fig4 #hj4 ,,power ,,consumption ,,and ,,efficiency ,,of ,,modified ,,reciprocating ,,pump4 ,the ,vacuum ,cleaner ,company used a ,clayton pump on its smaller plants which was fitted with a semi-rotary valve in each end serving as an induction and eduction valve1 while the heavy poppet eduction valve of the air compressor was dispensed with4 ,the increase in efficiency that should have resulted from this change was not realized4 ,the reason for this can be more readily seen by inspection of the indicator cards1 ,figs4 #ha and #hb4 ,fig4 #ha is a card taken from one of the ,clayton compressors fitted with combined induction and eduction valves1 and ,fig4 #hb a card from a compressor with light steel induction and eduction valves of the poppet type4 ,it will be noted that the compression line1 a-d1 ,fig4 #ha1 extends above the atmosphere line1 the pressure at the time of opening the eduction valve being #d lbs4 per square inch above the atmosphere4 ,this is due to the failure of the mechanically-operated valve to open soon enough4 ,this valve being also the induction valve1 it is necessary for the eduction port to be closed before the induction port can be opened1 in order to prevent a short circuit of air from the atmosphere into the separators4 ,this fact is responsible for the sudden increase in the pressure at b1 the eduction port having closed before the completion of the stroke and the air in the clearance space being compressed to #f lbs4 above atmosphere4 ,the induction port is not opened until after the beginning of the suction stroke resulting in the high degree of vacuum at c4 ,illustration3 ,,figs4 #ha ,,and #hb4 ,,indicator ,,cards ,,for ,,clayton ,,and ,,modified ,,pumps4 ,compare this with the card1 ,fig4 #hb4 ,here the compression does not extend above the atmosphere line more than lb4 per square inch and the eduction valve does not close until the end of the stroke so that the vacuum at the beginning of the suction stroke is no lower than during the entire stroke4 ,these pumps were working under the same conditions1 i4 e41 #ae-;in4 vacuum in the separator4 ,the ,m4 ,e4 ,p4 for ,fig4 #ha is #g4je while that in ,fig4 #hb is #f4g and is higher than is usually the case with this pump1 due to the fact that the exhaust pipe from this pump was very long and crooked1 a condition which should be avoided whenever possible4 ,also1 the pump from which this card was taken is one of the older pattern and the clearance was greater than in the later models4 ,the point at which the eduction valve opens in ,fig4 #ha is #ec of the stroke and it closes at #ie of the stroke and is1 therefore1 open #db of the stroke1 while in ,fig4 #hb the eduction valve opens at #df of the stroke and remains open to the end of the stroke1 and1 therefore1 is open for #ed of the stroke4 ,thus the pump with the poppet valves will move more air at the same vacuum with less expenditure of power than the pump with the mechanically-operated valves4 ,another type of reciprocating pump has been introduced in the past two or three years in which a single valve which rotates continuously in one direction is used for induction and eduction valve1 for both ends of the cylinder4 ,this valve is a plain cylindrical casting having ports cored through to alternately connect the cylinder ports with the intake and exhaust ports4 ,by rotating this valve #ahj on its stem the vacuum pump is changed to an air compressor4 ,this arrangement is adopted in order to discharge the contents of the separator into the sewer as was explained in ,chapters ,i and ,,viii4 ,in this pump there must be points at which both the induction and eduction valves are closed at the same time and results similar to those found with the semi-rotary valves of the ,clayton pump will naturally be in evidence4 ,the author has endeavored to obtain an indicator card from one of these pumps but has been unable to do so4 ,the effect of simultaneous closing of both induction and eduction ports would naturally be more marked in this pump than in the ,clayton1 as the motion of the valve in this case is uniform at all times while the motion of the valve gear of the ,clayton pump is so arranged that the valve moves very fast at the time that both ports are closed4 ,one of the two pumps of this type which was recently installed in the ,new ,york ,post ,office is illustrated in ,fig4 #hc4 ,these pumps have a displacement of #a1bjj cu4 ft4 each and are the largest reciprocating pumps in use for vacuum cleaning at this writing4 ,an interesting property of the piston pump which lends itself to the economical control of the vacuum in the system is illustrated by the curve at the top of ,fig4 #gh which shows the total power required to operate the ,clayton type air compressor1 the efficiency of which is indicated by the lower curves on this figure4 ,the compressor was operated at constant speed and the air volume varied to give various degrees of vacuum from atmospheric pressure to a closed suction and the power to operate the compressor read at intervals of two inches4 ,the current input to the motor in amperes is indicated by ordinates and the vacuum in the separator by the abscissae4 ,this indicates that the piston pump requires the maximum power to operate at about #ae-;in4 vacuum and that the least power is required when the vacuum is at the highest point possible to obtain4 ,the method employed in utilizing this characteristic of a piston pump will be discussed in a later chapter4 ,illustration3 ,,fig4 #hc4 ,,one ,,of ,,the ,,pumps ,,installed ,,in ,,connection ,,with ,,the ,,vacuum ,,cleaning ,,system ,,in ,,the ,,new ,,york ,,post ,,office1 ,,the ,,largest ,,reciprocating ,,pump ,,used ,,for ,,this ,,purpose ,,up ,,to ,,the ,,present4 ,rotary ,pumps4--,the ,garden ,city rotary pump is a good example of the single-impeller type of pump and is or has been used to some extent by at least two makers of vacuum cleaning systems4 ,its interior arrangement is shown in ,fig4 #hd4 ,a solid cylindrical impeller1 ,a1 is mounted eccentrically in the cylindrical outer casing1 the impeller being fitted with four sliding vanes which are provided with distance pieces1 ,e1 and wearing faces1 ,b4 ,the oil reservoir is provided with a needle valve which is automatically opened as soon as there is any vacuum produced and closes automatically when the machine is shut down4 ,the rate of feed of oil is adjusted by the screw ,i4 ,this type of pump offers a large surface in rubbing contact with the case and becomes very hot when in operation4 ,it requires liberal lubrication in order to prevent heating and cutting of the surface of the casing4 ,end wear in these pumps causes leakage1 and1 as usually constructed1 there are no means provided for taking up this wear4 ,it can be provided for1 however1 by using metal shims on the ends of the cylindrical casing4 ,illustration3 ,,fig4 #hd4 ,,interior ,,arrangement ,,of ,,the ,,garden ,,city ,,rotary ,,pump4 ,illustration3 ,,fig4 #he4 ,,power ,,required ,,to ,,operate ,,garden ,,city ,,type ,,of ,,rotary ,,pump4 ,the power required to operate this type of pump 7,curve a-b1 ,fig4 #he71 is nearly the same as that required to operate a piston pump for vacuum less than #ab in4 mercury1 but when the vacuum becomes higher1 the power required becomes much greater than that required by the piston pump4 ,the efficiency 7,curve c-e1 ,fig4 #he71 is identical with that obtained with the light-weight poppet valve pump 7,curve c-e1 ,fig4 #hj7 from #j to #aa in4 vacuum1 but for higher vacuum the efficiency of this type of pump falls off1 while the efficiency of the piston pump becomes greater as the vacuum becomes higher4 ,this difference in the characteristics of the two types of pumps is due to the presence of valves in one case and their absence in the other4 ,with the piston pump the atmospheric pressure reaches the cylinder only while air is being discharged1 the eduction valves being closed at other times and a partial vacuum exists on both sides of the piston4 ,the higher the vacuum produced1 the less time there is atmospheric pressure on the piston until1 when no air is discharged1 the air contained in the clearance space of the cylinder is compressed and expanded1 the compression and expansion lines being coincident4 ,the indicator card will have no area1 and the only power expended is that required to overcome the friction in the moving parts4 ,with the rotary pump there are no discharge valves to hold the atmospheric pressure from the discharge side of the impeller and the compression of the rarified air is accomplished by the atmospheric pressure admitting air through the eduction port into the chamber4 ,as it comes opposite the eduction port there is no difference in the time during which the impeller is subject to atmospheric pressure1 no matter what the quantity of air being discharged4 ,the higher the vacuum in the spaces containing rarified air1 the greater the difference in pressure on the opposite sides of the sliding vane and1 therefore1 the greater total power required to turn the rotor4 ,illustration3 ,,fig4 #hf4 ,,arrangement ,,of ,,double-,,impeller ,,root ,,type ,,rotary ,,pump ,,for ,,vacuum ,,cleaning ,,work4 ,another type of rotary pump which is fast becoming the most popular is the double-impeller type4 ,this is generally known as the ,root blower1 as the firm of this name was the first to manufacture same4 ,they have been in use for many years as blowers for gas works1 and as vacuum producers for various purposes1 mainly the operation of pneumatic tube systems4 ,why this form of vacuum producer was not earlier adopted in vacuum cleaning systems1 instead of the sliding-vane type1 is hard to understand4 ,this pump contains two impellers or cams which are mounted on shafts geared together and revolve in opposite directions inside of a case1 always being in close proximity to the case and to each other1 but never touching4 ,they are1 therefore1 frictionless in operation and the introduction of a small amount of water renders them practically air tight4 ,there being no metallic contact between the moving parts1 internal lubrication is unnecessary and there is no wear on either the impellers or the casing and no means of taking up wear are necessary4 ,the arrangement of the impellers and the method of providing water to seal the parts is shown in ,fig4 #hf4 ,a reservoir containing water is provided on the discharge side of the pump and a small pipe leads from this reservoir to the suction side of the pump4 ,the vacuum lifts water from the reservoir and discharges same in a spray into the suction chamber4 ,this water passes through the pump and is separated from the air in the discharge chamber to be returned to the suction chamber by the vacuum4 ,this operation will start automatically as soon as any degree of vacuum is formed and will cease as soon as the pump is shut down4 ,illustration3 ,,fig4 #hg4 ,,rotary ,,pump ,,arranged ,,with ,,double-,,throw ,,switch ,,for ,,reversing ,,pump4 ,any of these rotary pumps having no valves can be changed to an air compressor by reversing the direction of rotation4 ,this is adapted by the ,american ,rotary ,valve ,company in connection with their wet separators to discharge the contents of the separator into the sewer1 on all of their smaller-sized plants4 ,fig4 #hg shows one of these plants arranged with double-throw switch for reversing the electric motor used to operate the pump and also shows the arrangement of the rotary brush which is used to clean the screen in the wet separator1 as has been explained in ,chapter ,,viii4 ,illustration3 ,,fig4 #hh4 ,,power ,,consumption ,,and ,,efficiency ,,root ,,type ,,of ,,pump4 ,illustration3 ,,fig4 #hi4 ,,the ,,rotrex ,,vacuum ,,pump1 ,,used ,,by ,,the ,,vacuum ,,engineering ,,company4 ,the power consumption and efficiency of this type of pump are shown in ,fig4 #hh4 ,the watts per cubic foot of free air 7,curve a-b7 show a much lower consumption of power at the lower vacuum than any of the pumps already tested4 ,this is probably due to the fact there is no internal friction4 ,it will be noted that the power to operate at no vacuum is but #aj watts per cubic foot of free air1 while all the others require from #bd to #cd cubic feet4 ,this also results in the efficiency curve 7c-e1 ,fig4 #hh7 reaching its maximum value at a lower vacuum than in the case of the sliding vane pump 7,fig4 #he74 ,illustration3 ,,fig4 #ij4 ,,late ,,type ,,of ,,centrifugal ,,exhauster ,,made ,,by ,,the ,,spencer ,,turbine ,,cleaner ,,company4 ,the efficiency is fairly constant between #f-;in4 and #aj-;in4 vacuum and is much higher than is obtained with any of the other types of pumps at these vacua4 ,when they are operated at higher vacuum the efficiency is about the same as obtained with the sliding vane pumps and lower than that obtained with the reciprocating pumps4 ,the best efficiency of this pump is at the vacuum necessary to operate a cleaning system provided with #a-;in4 hose4 ,a slight modification of this type of pump is that used by the ,vacuum ,engineering ,company1 known as the ,rotrex4 ,this pump has but one impeller1 of nearly the same form as the impellers in the ,root blowers and has a follower driven by crank and connecting rods which is always in close proximity to the impeller but does not touch same4 ,the arrangement of this pump is illustrated in ,fig4 #hi which also shows the saturation chamber and screens used instead of a separator1 as explained in ,chapter ,,viii4 ,illustration3 ,,fig4 #ia4 ,,power ,,and ,,efficiency ,,curves ,,for ,,the ,,spencer ,,machine4 ,the author has never tested the economy of these pumps but would infer that their economy should be about the same as that of the ,root blower4 ,centrifugal ,exhausters4--,this type of exhauster has always taken the form of a fan4 ,the first stationary fan type of exhauster was manufactured by the ,spencer ,turbine ,cleaner ,company4 ,their latest type is illustrated in ,fig4 #ij4 ,it consists of a series of centrifugal fans mounted on a vertical shaft1 stationary deflection blades being provided between the wheels to conduct the air from the periphery of one wheel to the center of the next4 ,illustration3 ,,fig4 #ib4 ,,interior ,,arrangement ,,of ,,invincible ,,machine1 ,,manufactured ,,by ,,the ,,electric ,,renovator ,,manufacturing ,,company4 ,these centrifugal exhausters do not have a positive displacement1 as do all those already described1 and therefore the variation of the vacuum is not as much as in case of the positive displacement machines4 ,the vacuum produced when the machine is moving no air is slightly less than the maximum that the exhauster can produce and there is very little variation in the vacuum with air quantities which can be moved without exceeding the capacity of the motor or other means producing the power4 ,the curves showing the power required to operate and the efficiency of this type of vacuum producer are1 therefore1 plotted with abscissae representing the air moved in cubic feet per minute4 ,the vacuum produced and the power required to operate are plotted as ordinates4 ,the curves for the ,spencer machine are shown in ,fig4 #ia4 ,this curve is taken from a four-sweeper machine and the vertical lines numbered #a to #d represent the conditions when that number of sweepers are in operation2 that is1 bare floor renovators1 with #ej ft4 of hose or #hj cu4 ft4 of free air per minute4 ,the maximum efficiency is reached at full load and is approximately #db4 ,the vacuum at this efficiency is #e in4 mercury1 a drop of -in4 from the maximum which was obtained at one-fourth load4 ,illustration3 ,,fig4 #ic4 ,,power ,,consumption4 ,,vacuum ,,and ,,efficiency ,,of ,,first ,,types ,,of ,,invincible ,,machine4 ,these machines have rather large clearances and a preliminary separator is all that is required4 ,they operate at a speed of about #c1fjj ,r4 ,p4 ,m4 and the peripheral speed of the fans varies from #ae1jjj to #bb1jjj ft4 per minute4 ,this produces some noise and considerable vibration and care must be exercised in mounting the machine4 ,in order to insure quiet running the usual method is to place the machine on a felt pad of considerable thickness4 ,illustration3 ,,fig4 #id4 ,,power ,,consumption1 ,,vacuum ,,and ,,efficiency ,,of ,,invincible ,,machine ,,after ,,valve ,,was ,,fitted ,,to ,,discharge4 ,the machines made by the ,electric ,renovator ,manufacturing ,company are horizontal and have much smaller clearances than the ,spencer machines4 ,they operate at approximately the same rotary and peripheral speed and are1 therefore1 as noisy4 ,however1 the center of gravity of these machines is lower and the vibration is not so great4 ,the ,spencer ,company is now making a horizontal machine which it furnishes only when required1 the claim for their vertical machine being that the weight of the moving parts counteracts the thrust of the atmospheric pressure against the fans and relieves the work of the thrust bearings1 at the expense of greater vibration4 ,with ball bearing thrusts1 the author does not consider this to be of great importance4 ,a view of the interior arrangement of the ,invincible machine1 as manufactured by the ,electric ,renovator ,manufacturing ,company1 is shown in ,fig4 #ib4 ,these machines1 when first made1 were without valves and the power consumption1 vacuum and efficiency are shown in ,fig4 #ic4 ,it will be noted that the vacuum produced1 when the machine is operated at or below one-half load1 is considerably lower than is obtained at greater loads4 ,this characteristic produces a disagreeable noise when the machine is not handling any air1 evidently due to air rushing back through the outlet when the vacuum tends to build up to the maximum which occurs at intervals of about one-half second4 ,illustration3 ,,fig4 #ie4 ,,four-,,sweeper ,,invincible ,,plant ,,installed ,,in ,,the ,,united ,,states ,,post-,,office ,,at ,,los ,,angeles1 ,,cal4 ,in order to overcome this trouble a valve has been fitted to the discharge1 as indicated at #d1 ,fig4 #ib4 ,with this valve in place the power consumption1 efficiency and vacuum are as shown in ,fig4 #id4 ,it will be noted that the vacuum is as high at no load as at any load up to full load and is practically constant4 ,the efficiency at light loads is the same as before but it is slightly lower at full load1 being #ej without the valve and #dg with the valve4 ,this is due to the power being expended in opening the valve for large quantities of air and to friction in the valve passage4 ,a four-sweeper plant of this manufacture is shown in ,fig4 #ie4 ,this plant is installed in the ,united ,states ,post ,office at ,los ,angeles1 ,cal4 ,the separate centrifugal separator1 shown at the left of the cut1 is not used in the regular equipment and was added in this case to fulfill the specification requirements4 ,a centrifugal pump with a single impeller is manufactured by ,the ,united ,electric ,company and is known as the ,tuec system4 ,a phantom view of the pump and separator is shown in ,fig4 #if4 ,it will be noted that the shaft is vertical4 ,however1 the vacuum is under the impeller in this case1 and the thrust due to the atmospheric pressure is down instead of up1 as in the case of the ,spencer machines4 ,this throws the weight of the parts1 plus the thrust due to atmospheric pressure1 on the thrust bearing4 ,these machines do not produce a vacuum greater than #c-;in4 mercury1 and the additional thrust is not as great as in the case of the machines producing higher vacuum1 the impeller being #bd in4 in diameter1 its area #dej sq4 in4 and the thrust1 with a vacuum of #c-;in4 mercury1 #fge lbs41 which is worth considering4 ,this downward thrust is partially counterbalanced by mounting the armature of the electric motor used to operate the fan1 slightly below the magnetic center1 thereby causing an upward magnetic pull4 ,these machines are intended to be used with large hose and pipe lines to reduce the friction to a very low point4 ,when operating carpet renovators the vacuum at the renovator rises to #a--;in4 mercury and the type of renovator used by them passes approximately #ej cu4 ft4 of air1 while the bare floor renovators pass approximately #ie cu4 ft4 ,they are extensively used where bare floor work is required1 their first cost being low4 ,the results of tests of two of these machines of four-sweeper capacity1 driven by alternating and direct-current motors1 respectively1 are shown in ,fig4 #if;a4 ,these curves indicate a considerably higher efficiency with the alternating than with the direct-current motor4 ,this is due to the low efficiency of the special high-speed direct-current motors used with all centrifugal fan-type exhausters4 ,the alternating-current motors are not so affected1 in fact1 the speed at which these fans are operated is fixed by the requirements of the alternating-current motors4 ,illustration3 ,,fig4 #if4 ,,centrifugal ,,pump ,,with ,,single ,,impeller1 ,,manufactured ,,by ,,the ,,united ,,electric ,,company4 ,the efficiency of the other types of centrifugal exhausters 7,figs4 #ia1 #ic and #id7 is in every case accomplished with direct-current motors4 ,this machine has an efficiency about the same as the ,spencer machine4 ,it will be noted that the vacuum produced does not fall off as the load increases1 as in the case of the multi-stage fans4 ,this characteristic is probably due to the fact that there is no wire drawing in the diversion vanes1 as in the case of the multi-stage exhauster4 ,illustration3 ,,fig4 #if;a4 ,,test ,,of ,,centrifugal ,,pump ,,with ,,single ,,impeller4 ,steam ,aspirators4--,the steam aspirator as a vacuum producer in connection with vacuum cleaning systems was first used by the ,american ,air ,cleaning ,company1 and has been used to a limited extent by the ,sanitary ,devices ,manufacturing ,company4 ,the type of apparatus used by the ,american ,air ,cleaning ,company is illustrated in ,fig4 #ig4 ,a single partial separator is used with this system and the lighter dust is allowed to pass through the aspirator1 where it is mixed with the steam and sterilized4 ,the aspirator is in the form of an ejector1 with a specially designed nozzle1 and is always fitted with an automatic device for cutting off the steam when the vacuum in the separator reaches the degree desired4 ,illustration3 ,,fig4 #ig4 ,,steam ,,aspirator ,,used ,,by ,,the ,,american ,,air ,,cleaning ,,company4 ,the steam consumption required to exhaust #a cu4 ft4 of free air at various vacua1 as determined by actual test of four different nozzles1 is shown in ,fig4 #ih1 the steam being the actual weight of dry and saturated steam at the gauge pressures noted4 ,the ,american ,air ,cleaning ,company used to guarantee a steam consumption of #bej lbs4 per hour from and at #bab ,f41 assuming that the feed water temperature was #cb ,f41 the vacuum to be maintained at #i in4 mercury at the aspirator4 ,taking the results of the test of the three-sweeper nozzle as an average1 #j4jff lbs4 of steam will be required to exhaust #a cu4 ft4 of free air at #i in4 vacuum4 ,the total heat in #a pound of dry steam at #aaj lbs4 gauge is #aahg ,b4 ,t4 ,u4 and at #bab ,f4 the latent heat is #igj ,b4 ,t4 ,u4 ,the factor of evaporation1 therefore1 is #a4bce1 and the weight of steam at #aaj lbs4 allowed by the guarantee is #bjb lbs4 ,this amount of steam will exhaust #c1jfj cu4 ft4 per hour1 or #ea cu4 ft4 per minute1 which is more than sufficient to operate a carpet renovator1 and is a little less than will pass through a bare floor brush attached to the end of #ej ft4 of #a in4 diameter hose1 if the hose is attached directly to the aspirator4 ,with a line of pipe between the hose cock and the aspirator1 the air quantity will be somewhat less1 and this guarantee will undoubtedly be fulfilled in every case4 ,illustration3 ,,fig4 #ih4 ,,steam ,,consumption ,,of ,,steam ,,aspirator4 ,the advisability of using an aspirator will depend on the conditions to be met at the building in each case4 ,three typical cases are cited below3 #a4 ,when there is a ,generating ,plant in the ,building1 and a ,plant ,using #a-;in4 ,hose and #h-;in4 ,vacuum is ,desired4--,a ,root blower will require #bg watts for each cubic foot of air exhausted 7,fig4 #hh71 and the three-sweeper aspirator1 #j4jfe lbs4 of steam4 ,then the pounds of steam required by the aspirator to do the same work as one ,k4 ,w4 hour at the motor of the ,root blower will be #j4jfe #fj ---------- #adf4c #j4jbg ,the generating plant will produce a kilowatt hour at the switchboard with not exceeding #fj lbs4 of steam1 and if the transmission loss is #aj there will be required by the ,root blower not over #ff lbs4 of steam to do the same work that takes #adf lbs4 with the aspirator4 ,this case would require that the ,root blower1 driven by an electric motor1 be used4 #b4 ,when there is ,high ,pressure ,steam ,available1 but no ,generating ,plant4--,then we may use either the aspirator or a ,root blower driven by a steam engine4 ,this engine should have an economy of #fj lbs4 per indicated horse power1 with not over #ae friction loss1 which will require #fi lbs4 per brake horse power4 ,this will be equivalent to #fi #j4ggf #ij lbs4 per ,k4 ,w4 hour1 which is still much better than #adf lbs4 required by the aspirator4 #c4 ,when ,steam is ,generated on the ,premises with ,coal ,costing #c4jj per ton and all ,machinery ,must be ,driven by ,electricity ,purchased for #e ,cents per ,k4 ,w4 ,hour4--,cost of steam to do the same work in the aspirator that #a ,k4 ,w4 hour will do in a motor driving a ,root blower is3 #adf #cjj --------- #b4h cents #g #bbdj as against #e cents that would have to be paid for current4 ,in this case there would be a saving in using the aspirator1 which would not require as much attention as the motor1 and at loads less than full load1 the steam used by the aspirator would be in direct proportion to the load1 as the control would shut the steam off entirely during a portion of the time1 while the motor would require some current as long as it was in operation1 even if no air was being exhausted4 ,on the other hand1 the steam which is exhausted from the aspirator is not suitable for use in heating1 as it is mixed with air and fine dirt1 and must be thrown away1 a condition that must always be considered where there is an opportunity to use exhaust steam for heating or other purposes4 ,,chapter ,x4 ,,control4 ,when the displacement type of vacuum producer of more than one-sweeper capacity is used with a vacuum cleaning system1 some means must be employed to prevent the vacuum rising above that necessary for efficient operation of the sweepers when there are less renovators in use than the capacity of the vacuum producer or when carpet renovators are in use on all outlets4 ,if the displacement pump be run at constant speed1 every change in the quantity of air exhausted will cause a change in the vacuum produced4 ,this will result in inefficient operation and may result in undue effort being necessary to operate the renovator and in excessive wear on the carpets4 ,the earlier systems were not provided with any control and the first attempt to control the vacuum was by placing a spring relief valve on the pipe line near the separator1 which admitted additional air when the vacuum tended to rise4 ,this resulted in full load being thrown on the pump at all times when the same was in use1 which does not give economical operation4 ,the controllers that have been devised for maintaining a constant vacuum without the introduction of air into the system operate on one of three principles3 #a4 ,closing the suction of the vacuum producer4 #b4 ,opening the suction of the vacuum producer and holding vacuum in the system4 #c4 ,varying the speed of the vacuum producer4 ,illustration3 ,,fig4 #ii4 ,,first ,,type ,,of ,,controller ,,introduced ,,by ,,the ,,sanitary ,,devices ,,manufacturing ,,company1 ,,known ,,as ,,the 8,,unloading ,,valve40 ,the first type of controller was introduced in the vacuum cleaning field by the ,sanitary ,devices ,manufacturing ,company1 and was known as the 8unloading valve40 ,it was similar to the unloader which had been used for some time in connection with air compressors4 ,the detail of construction is shown in ,fig4 #ii1 and consists of a balanced valve1 which is connected to a weighted piston1 operating in a chamber communicating with the separators by a pilot valve4 ,the pilot valve is operated by an auxiliary piston which is weighted to overcome the lifting effort due to the vacuum desired4 ,when the vacuum in the cylinder becomes great enough to overcome the weights attached to the auxiliary piston1 it rises1 allowing vacuum to reach the main piston1 which is drawn up and the suction valve closed4 ,when this valve is closed the vacuum in the pump at once starts to build up to the maximum possible for the pump to produce1 and if the pump used is of the piston type the vacuum will run up to nearly #bh in41 resulting in the pump's taking the least power on which it can be operated4 ,as soon as the vacuum in the separators falls below that which will sustain the weight on the auxiliary piston the valve falls open and the pump again draws air through the system4 ,in actual practice this valve will operate at more or less frequent intervals4 ,the author timed the action of one of these valves connected to the suction of an eight-sweeper piston pump1 and its time varied from second to #fe seconds4 ,the current taken by the pump when the suction was open was #ajj amperes at #bbj volts4 ,when the valve was closed for but second the current dropped to #ge amperes1 there not being sufficient elapsed time for the pump to produce a perfect vacuum4 ,when the valve was closed for #b seconds1 the vacuum reached its maximum value and the current fell to #cb amperes4 ,fig4 #ajj is a curve plotted from the results of this test and shows an increase in the power above that necessary to overcome the friction in the moving parts of the pump in direct proportion to the percentage of full load that the pump was serving4 ,illustration3 ,,fig4 #ajj4 ,,test ,,of ,,controller ,,connected ,,to ,,suction ,,of #h-,,sweeper ,,piston ,,pump4 ,this is as near an ideal condition as one could expect to obtain by any means other than stopping the pump or otherwise decreasing the friction load4 ,however1 this form of unloader is not suitable for a pump without valves1 as the power will increase with an increase in vacuum1 and other means must be employed to control such a pump4 ,the second form of control is adapted to this type of pump4 ,the arrangement of one of these controls is shown in ,fig4 #aja4 ,this consists of a single-ported valve opened by the vacuum in the cylinder1 ,m1 the action of which is controlled by a pilot or auxiliary control valve actuated by the vacuum in the separator4 ,this auxiliary valve is fitted with two pistons1 ,s and ,o1 which are held together by springs1 and when so held the main cylinder is open to the atmosphere through the small ports in the piston1 ,o4 ,when the vacuum in the separator becomes great enough to overcome the compressive strength of the springs1 ,t and ,p1 the pistons1 ,s and ,o1 are drawn apart1 closing the port in the piston1 ,o1 and opening the port in piston1 ,s1 allowing the vacuum to enter the main cylinder1 ,m1 and open the main valve4 ,this valve permits the atmospheric pressure to enter the pump suction1 the air being prevented from entering the separators by a check valve1 not shown4 ,the pump then operates without producing any vacuum1 and the power required to operate the pump is reduced4 ,a relief valve of the common vacuum-breaker type is shown at the left of the cut4 ,this valve is provided to prevent overload in case the control fails to operate4 ,illustration3 ,,fig4 #aja4 ,,type ,,of ,,controller ,,for ,,use ,,on ,,pumps ,,without ,,valves4 ,this type of control does not effect as great a reduction in the power as the first type of control described1 since it requires a greater per cent4 of the full load power to operate the pump at no vacuum than at perfect vacuum4 ,no air is moved in the latter case1 and the maximum volume of air is moved in the former case4 ,either of these controls gives fairly economical results when the pump is serving at least a part of the sweepers at all times4 ,however1 when the system is used in a building where there may be cleaning done at any time and vacuum must be 8on tap0 at all times1 as in a hotel1 there will be many occasions when no sweepers will be in use1 and the pump might then be stopped entirely1 provided that it could be automatically started when needed4 ,illustration3 ,,fig4 #ajb4 ,,regulator ,,for ,,motor-,,driven ,,vacuum ,,pump1 ,,manufactured ,,by ,,the ,,cutler-,,hammer ,,manufacturing ,,co4 ,where the steam aspirator is used1 the control 7,fig4 #ig7 is attached to the steam supply valve4 ,when the valve is closed no steam is consumed by the aspirator4 ,this is the ideal condition where we must keep vacuum 8on tap10 and is a characteristic of the aspirator system which has led to its introduction in many instances4 ,the same economy can be obtained with a steam-driven pump by inserting a throttle valve1 controlled by the vacuum in the separators1 which will start and stop the engine driving the pump and vary its speed in accordance with the quantity of air required by the system4 ,several appliances for varying the speed of a motor-driven vacuum pump have been placed on the market1 the simplest and probably the best of these appliances being that manufactured by the ,cutler ,hammer ,manufacturing ,company1 illustrated in ,figs4 #ajb and #ajc4 ,illustration3 ,,fig4 #ajc4 ,,inspirator ,,type ,,vacuum ,,contactor1 ,,used ,,to ,,control ,,pilot ,,motor ,,of ,,cutler-,,hammer ,,controller4 ,the object of the apparatus shown in ,fig4 #ajb is to automatically start a motor-driven vacuum pump and control the speed of the motor so that the vacuum is maintained at the desired degree1 irrespective of variation in the number of sweepers in use4 ,this control of the degree of variation is accomplished in a more efficient manner than if the pump were to be driven at its maximum speed at all times and the pressure kept at the desired point by means of a blow-off or by-pass valve4 ,with this system a motor is used having a control1 by shunt field weakening1 of approximately #c3a in order that the control of the speed may be as efficient as possible4 ,referring to ,fig4 #ajc1 a small pilot motor is mounted on brackets at the side of the panel1 driving directly1 through an insulating coupling1 a screw shaft which carries a traveling cross-head4 ,this cross-head is shown in the photograph at the extreme right of its travel1 which corresponds to the maximum speed of the motor1 the left-hand end corresponding to zero speed of the motor4 ,in this position the motor circuit is opened by the clapper type magnetic switch4 ,assuming that the cross-head is in the extreme left-hand position and the knife switch is closed1 the pilot motor will be started in such a direction as to move the cross-head to the right4 ,a slight movement in this direction completes a connection to the magnetic switch1 which thereupon closes the motor circuit through all of the resistance1 starting the pump motor4 ,inasmuch as the pilot continues to move the cross-head toward the right1 the speed of the pump will be gradually increased until1 at a point about midway of its travel1 all of the resistance in the armature circuit of the motor will have been cut out upon the upper segments and further movement then serves to weaken the field4 ,this is accomplished by means of the contact buttons shown just below the screw shaft4 ,as soon as the cross-head has weakened the field to its minimum value and thus speeded the motor up to its maximum point1 a limit switch stops the pilot motor and thus prevents further motion in that direction4 ,as soon as the pump working this at its maximum speed has produced a vacuum in the cleaning system of1 say1 #ab in4 of mercury1 the cross-head will begin to move backward and reduce the speed to a point corresponding with the air required4 ,this control of the pilot motor is accomplished by means of what is termed 8inspirator type vacuum contactor40 ,this apparatus is shown more in detail in ,fig4 #ajc1 and consists of a diaphragm closing one side of a chamber4 ,the diaphragm is pressed outward by an internal spring whose tension may be adjusted by means of a hexagonal head cap screw1 visible in the photograph of the complete regulator4 ,the diaphragm is coupled to a pivoted arm carrying insulated conical-pointed silver screws1 so located that they enter holes in small silver plates mounted on opposite sides1 respectively1 of the upper and lower contact posts4 ,these contact posts are hollow and communicate with the diaphragm chamber1 which latter is connected by piping to the vacuum system4 ,normally1 the internal spring forces the diaphragm over so that the lever makes contact with the lower post4 ,this serves to drive the pilot motor in a direction to move the cross-head to increase the speed of the pump4 ,when the degree of vacuum for which the apparatus is adjusted is reached the lever starts to move toward the left hand1 and in so doing stops the pilot motor4 ,this maintains the pump speed at that particular value4 ,should the vacuum increase to a sufficient degree the lever will be drawn further over toward the left and contact will then be established with the upper post1 which will cause the pilot motor to move the cross-head to the left1 and thus decrease the pump motor speed4 ,inasmuch as the motion of the diaphragm lever is very gradual1 destructive arcing would take place at the pilot motor contacts were it not for the small openings in the silver contact plates1 which1 as the pointed screw leaves the hole1 immediately sucks the arc inward and extinguishes it4 ,this method of preventing arcing is exceedingly unique and is subject to patents now pending4 ,it is possible to adjust the high and low limits by changing the setting of the pointed silver screws1 the usual adjustments being such as to maintain the vacuum within #b in4 of mercury4 ,the speed of the pilot motor may be adjusted by means of the small link shown in the upper left-hand corner of the panels to correspond with the capacity of the system1 it being found that systems of large capacity require a slower motion than those in which the amount of piping1 etc41 is less for the same size of pump4 ,in practice1 the regulator will very quickly find the position corresponding to the proper speed for the number of outlets in use1 and only moves a slight amount either side of this particular position4 ,with this regulator it is possible to employ remote control permitting the establishment of vacuum in the piping system by the turning of a pilot switch located at any point in the building4 ,if desired1 several such switches may be placed in parallel1 and1 under these conditions1 the turning on of any switch will establish the vacuum supply which will be maintained until all of the pilot switches are turned off4 ,by this means it is possible to have several janitors working at the same time on different floors of the building1 and each will be independent of the others in his control of the vacuum2 although one man may finish and turn off the switch on his floor1 the pump will not be stopped if the vacuum is still required by workers on other floors4 ,when the total size of one installation becomes greater than #be ,h4 ,p41 it is found desirable to provide two pumping units1 and1 in this case1 the same system is applicable4 ,the cross-head is then arranged to start first one pump and increase its speed to a maximum4 ,if this does not supply the necessary amount of air1 the cross-head continues to move1 and starts the second pump1 which will then be run at a necessary speed to supply the remaining amount of air4 ,the first pump always remains in motion at its point of highest efficiency4 ,it is evident that this duplex arrangement is more efficient than one large pump when only a very few sweepers are in operation1 since1 for this condition1 the very large pump would have to be run at such a slow speed that the armature resistance would be in circuit1 while the single smaller pump would be running at a more efficient speed and with less proportionate motor losses4 ,in duplex outfits switches are provided for disconnecting either motor in case of its being necessary to clean or repair either unit4 ,when so disconnected the other unit may be operated and maintain the same degree of vacuum within the limits of its capacity4 ,while this type of control is more economical in current consumption than either of the former types described1 its cost is much higher1 and it is seldom used unless specifically ordered4 ,when the centrifugal type of vacuum producers is used no control is necessary1 as the inherent feature of this type of apparatus insures a practically constant vacuum at all air quantities within the capacity of the machine4 ,,chapter ,,xi4 ,,scrubbing ,,systems4 ,vacuum cleaning systems in which appliances for scrubbing are provided in addition to the usual appliances for the removal of the dust and other materials in a dry state have been introduced by a few manufacturers1 none of which has come into general use4 ,the usual method employed is to provide an ordinary corn scrubbing brush which has a connection to the water supply of the building1 with control valves in the tool handle for regulating the flow of water to the brush4 ,soap is applied either in the form of soap powder sprinkled on the floor1 in a liquid state fed into the water supply by means of a sight-feed oil cup or soft soap in a plastic state fed into the water supply by means of a compression grease cup4 ,in any case1 the water is run onto the floor mixed with the soap and the floor scrubbed by manipulating the corn brush1 in the same manner that an ordinary corn scrubbing brush without attachments would be used4 ,after the dirt has been loosened from the floor1 the floor may be rinsed by the application of more water4 ,the water is then drawn up from the floor by the suction of the cleaning machine1 and passes through the hose and piping system to the separator and vacuum producer4 ,to effectively remove the water a rubber-faced tool is usually employed4 ,in one system this rubber face is arranged to permit the corn brush to be fitted over same when scrubbing is being done1 and the brush must be removed from the tool before the water can be drawn up from the floor4 ,other manufacturers provide a double-faced tool having the brush on the opposite side of the tool from the rubber-faced slot4 ,by reversing the tool1 scrubbing and mopping can be accomplished without the removal of the corn brush from the tool1 which is more convenient for the operator4 ,with either of the above forms of scrubbing tools it is necessary or desirable to cut off the suction to the mopping attachment when using the corn brush1 and it is also necessary to cut off the water supply to the brush when using the mopping attachment4 ,one system1 introduced several years ago1 conducted the water to the brush and away from the rubber-faced mopping appliance through the same hose4 ,this arrangement requires the use of a special three-way hose cock1 which had to be manipulated frequently during the scrubbing operation1 requiring the time of another person in addition to the operator1 or else greatly delaying the scrubbing process by requiring the operator to constantly pass back and forth between the hose cock and the scrubbing tool4 ,this method of supplying water also requires the use of a removable corn brush attached over the rubber mopping device4 ,other forms of scrubbing appliances are provided with separate hose for the water supply and suction and with valves in the handles for controlling the suction and water supply4 ,these valves to be efficient and quick in action are generally made self-closing1 otherwise they will be short-lived1 as explained in ,chapter ,v4 ,when springs are used to close the valves1 the hand and wrist will be quickly fatigued1 as stated in ,chapter ,v4 ,with either of the above systems all of the scrubbing1 that is1 the agitation of the brush1 has to be performed by the operator1 as in the case of the ordinary scrubbing brush4 ,however1 the combination tool is much heavier and clumsier than the ordinary scrubbing brush1 and the only advantage obtained by using this heavy and clumsy appliance is the ability to supply water without carrying it in buckets1 also the removal of the dirty water after scrubbing4 ,these appliances cannot be termed mechanical scrubbers1 nor can they be classed with scrubbing machines with motor-driven brushes1 such as have been recently introduced4 ,a real mechanical scrubbing device for use with a vacuum cleaning system was manufactured by ,foster ,glidden1 of ,buffalo1 ,n4 ,y41 but was never placed on the market1 although at least one is in commercial operation to-day4 ,this machine is provided with a turbine motor operated by the air current passing through the machine4 ,this turbine revolves a pair of scrubbing brushes turning in opposite directions4 ,water is fed through a separate hose1 and an auxiliary air inlet is opened when the suction under the brushes is closed1 in order to supply the necessary air to keep the turbine running4 ,mr4 ,foster states that he has experienced no trouble in operating this machine on from #h in4 to #ab in4 of vacuum1 being able to scrub and remove the dirt and water with one operation4 ,the speed with which the work was done depended on the condition of the floor1 the usual rate1 as given by ,mr4 ,foster1 being from #aj to #ab yds4 per minute4 ,mr4 ,foster also states that he has not pushed the introduction of this scrubber1 as he considers it so far ahead of the times as to require the education of the public in the use of the hose and ordinary vacuum cleaning tools before users would be capable of successfully operating this type of scrubber4 ,the author considers this condition to be lamentable if true1 for until some such appliance is in commercial use scrubbing attachments to a vacuum cleaning system can never compete with the mechanical scrubbing machines now on the market1 and are little if any better than the old method of scrub-brush1 mop and pail1 and certainly not as rapid in operation4 ,when the vacuum cleaning systems combine scrubbing with dry cleaning1 the separator and vacuum producer must provide for the removal of water as well as air4 ,a few manufacturers have attempted this1 among which are the makers of the ,rotrex system1 described in ,chapter ,,ix1 in which the water is passed through the pump and into the sewer under sufficient pressure to overcome the friction in the exhaust pipe through which the expelled air passes after leaving the separator4 ,this may be sufficient to force the trap seals of the plumbing system1 and1 if used1 the discharge connection should be made to the sewer outside the main running trap1 close to the fresh air inlet4 ,as large articles cannot be allowed to pass through the pump1 a screen is necessary on the inlet side of the vacuum producer1 but this may give trouble1 due to the clogging with litter4 ,the ,atwood ,vacuum ,cleaner ,company uses a wet tank on the suction side of the vacuum producer into which the dirt and water are discharged1 the air being separated and passed to the vacuum producer4 ,when this tank becomes partly filled it is necessary to shut down the plant and empty the contents of the tank by gravity into the sewer4 ,this method overcomes the objections to clogged screens and forced trap seals1 and all litter is discharged direct to the sewer1 together with a quantity of water which is presumably sufficient to flush the litter through the sewer4 ,the last named system is still open to two objections2 first1 it is not automatic1 and1 if neglected1 the tank will fill with water and force same into the vacuum producer4 ,with the ,root type of vacuum pump this will do little harm unless a large quantity of floating litter should pass into the pump4 ,second1 the system may be operated with dry renovators exclusively for a considerable portion of the time1 in which case the contents of the separator may become of such a consistency as will not readily flush through the sewer1 and stoppage of the same may occur4 ,another separator of this type has recently been patented by ,e4 ,b4 ,dunn1 the originator of the ,dunn ,locke1 in which the mud and the water are automatically discharged alternately from one of two separators1 as described in ,chapter ,,viii4 ,such a separator1 in which sufficient water is automatically introduced to dilute the dirt and which will automatically empty when sufficiently filled1 when so constructed that it will operate continuously1 is considered to be the ideal separator for use with a combined cleaning and scrubbing system4 ,until the mechanical scrubber and an automatically operated separator are commercially introduced the author does not consider that the use of scrubbing attachments1 in connection with the vacuum cleaning system1 is advisable4 ,,chapter ,,xii4 ,,selection ,,of ,,cleaning ,,plant4 ,we have considered in detail the various appliances which1 taken together1 make a complete vacuum cleaning system1 but without considering their relation to one another4 ,it now becomes necessary to choose an exact type and form of each of these appliances which will produce in combination a complete vacuum cleaning system best suited to the conditions to be met in a given installation4 ,in selecting a vacuum cleaning system consideration must be given to the character of the material to be removed1 the kind and quality of the surfaces to be cleaned1 the rate at which cleaning must be done1 the extent of the cleaning system1 and the cost of labor to operate the system1 all of which must be considered in each step in the selection of a suitable plant4 ,in assembling the complete system1 the author will take up the various parts thereof in the order in which they were discussed in the preceding chapters4 ,renovators4--,the selection of renovators is the most important step in making up a vacuum cleaning system1 as the entire makeup of the system1 whether good or bad1 is dependent on the proper selection of these tools4 ,the carpet renovator is generally considered first in importance1 because the cleaning of carpets has nearly always been found to be the principal field of usefulness in vacuum cleaning work4 ,this is due1 perhaps1 largely to the fact that from the beginning of the art of vacuum cleaning1 this function of the system has been held before the eyes of the public by the manufacturers of the earlier systems4 ,nearly all demonstrations of cleaning systems shown to the public consist of the removal of ordinary wheat flour from a carpet4 ,the reason for this is two-fold2 first1 because it is the most striking demonstration to the eye of the layman1 and1 second1 it is the easiest to accomplish with a small air displacement and small power1 which was characteristic of the apparatus made by these manufacturers4 ,the author was at one time of the opinion that this function of the cleaning plant was given too much prominence by builders of systems having small air displacement1 and letters were sent to the officials in charge of sixteen ,government buildings in which vacuum cleaning systems were installed1 asking them1 among other questions1 whether the cleaning system was used to any extent in cleaning bare floors1 of which there were large areas1 both wood and marble1 in the buildings in question4 ,the plants installed were of various makes1 some of which maintained #ab in4 mercury at the separator and used #a-;in4 hose1 while about an equal number of others maintained #f in4 mercury at the separator and used #a-;in4 hose4 ,the answers showed that out of the sixteen buildings the cleaner was used on bare floors in but two of the buildings4 ,one writer1 who had a plant maintaining #f-;in4 vacuum1 provided with ,type ,f renovators and #a-;in4 hose1 stated that he had tried cleaning bare floors without success1 as the renovator and hose became so clogged with litter as to be inoperative4 ,the majority stated that the cleaning system displaced brooms on carpets and rugs and several stated that the cleaning system was used to advantage in cleaning walls1 cases1 pigeon holes and relief work4 ,this indicates that for the average office and departmental building the cleaning of carpets is the most important function of the vacuum cleaner4 ,this is also true of residence work4 ,schools1 department stores and manufacturing buildings contain very little floor space covered with carpets1 and in buildings of this character the cleaning of bare floors is of the greatest importance4 ,in such cases the efficiency of the carpet renovator can be sacrificed to a more efficient and economical operation of bare floor renovators4 ,in a building where carpet cleaning is an important function of the cleaning system1 the selection of the carpet renovator is most important4 ,of all the various types of carpet renovators discussed in ,chapter ,,iii1 only two need to be considered1 ,type ,a and ,type ,f4 ,of these1 ,type ,a is superior in all respects except the picking up of large litter1 and1 unless the character of the material to be removed contains a large amount of material which can be picked up by ,type ,f renovator that will not pass ,type ,a1 ,type ,a renovator should always be used4 ,even when ,type ,f renovators are desirable1 the writer considers that the plant should still contain some ,type ,a renovators for use in places where this unusual litter will not be encountered4 ,among the bare floor renovators1 described in ,chapter ,,iv1 only the one having a felt face1 curved to permit its running over the dirt1 is worthy of serious consideration4 ,this renovator requires an inlet or vacuum breaker to keep same from sticking to the surface cleaned1 the extent of such opening being dependent on the vacuum maintained in the carpet renovators1 as explained in ,chapter ,,vii4 ,when carpet cleaning is considered as of secondary importance to bare floor cleaning1 the degree of vacuum maintained at the separators may be reduced to that which will produce a vacuum of #a in4 mercury at the bare floor renovator1 allowing the vacuum maintained at the carpet renovator to be whatever the conditions of hose and pipe line will produce4 ,under such conditions1 the area of the inrush or vacuum breaker in the bare floor renovator may be reduced considerably4 ,the use of brush renovators is dependent on the capacity of the air exhauster supplied1 as explained in ,chapter ,,vi4 ,if it is decided that brush renovators are necessary1 then the 8large volume0 exhauster must be installed4 ,the advisability of such installation is dependent on the time allowed for cleaning and the cost of the operators4 ,in residences and small buildings where the cleaning operations can be done with one or even two domestics or laborers1 very little1 if any1 saving in the wages of operators can be effected by increasing the rate at which the cleaning can be done4 ,in such buildings a small-volume plant will be the most economical in first cost and operation4 ,if such a plant is installed1 the brush renovators should be omitted4 ,in cases where bare floor cleaning is the principal function of the cleaning system the extra quantity of air at the low vacuum necessary will not require much larger expenditure of power than that needed by the small-volume plants when maintaining sufficient vacuum for effective carpet cleaning and brush renovators should be provided with systems of this character4 ,hose4--,in ,chapter ,,vi it is shown that when carpet renovators are operated efficiently in combination with bare floor renovators1 #a-;in4 hose will produce the best results with the lowest expenditure of power at the hose cock4 ,in ,chapter ,,vii it is shown that with pipe lines of ordinary length #a-;in4 hose also gives the best results1 with the least expenditure of power at the separator1 but that in cases of exceedingly long pipe lines1 #a-;in4 hose will be the most economical4 ,in a system where bare floor cleaning is the principal function1 the vacuum to be maintained at the carpet renovator is no longer considered1 and for such systems the largest hose which can easily be handled will cause the least hose friction and require the lowest vacuum at the hose cock4 ,it is1 therefore1 the most economical to use on such a system4 ,the author does not recommend the use of a hose larger than #a--;in4 diameter for this type of plant4 ,the proper hose sizes1 therefore1 will be3 ,for ordinary buildings where carpet cleaning is important1 #a-;in4 diameter4 ,for installations with unusually long lines of piping1 where carpet cleaning is important1 #a-;in4 diameter4 ,for all systems where carpet cleaning is of secondary importance1 #a-;in4 or #a--;in4 diameter4 ,pipe ,lines4--,pipe lines should always be as large as possible without reducing the velocity in same below #dj ft4 per second1 as explained in ,chapter ,,vii4 ,separators4--,the type of separator to be used is dependent on the type of vacuum producer adopted4 ,where reciprocating exhausters are used1 or other type of exhauster where there is rubbing contact between the moving parts and the dust1 the combination of a wet and dry separator is recommended4 ,when rotary or centrifugal exhausters having close clearances are used1 total separators with bags are recommended4 ,when exhausters with large clearances are operated1 partial separators are satisfactory4 ,the use of any form of apparatus contemplating the adoption of a satisfactory scrubbing system is not considered advisable1 as the author believes that separators for handling water will be improved before scrubbing becomes commercially successful4 ,changes in the existing separators can be made when satisfactory scrubbing appliances are placed on the market1 at no greater expense than would be necessary to bring up to date any of the present systems for handling water4 ,vacuum ,producers4--,the selection of the vacuum producer is dependent on the degree of vacuum that must be maintained to effectively operate the system selected4 ,for the operation of a system where carpet cleaning is the principal function and #a-;in4 hose is used1 the vacuum required at the producer will be from #f in4 to #i in4 mercury4 ,inspection of the efficiency curves of the various types of vacuum producers1 given in ,chapter ,,ix1 shows that the two-impeller rotary pump has the highest efficiency at this vacuum4 ,for the operation of systems where carpet cleaning is the most important function and #a-;in4 hose is found to be the most economical1 #ad in4 to #ae in4 of vacuum at the vacuum producer is necessary1 and efficiency curves1 given in ,chapter ,,ix1 show that the piston pump is the best suited for such service4 ,for the operation of a system where carpet cleaning is of secondary importance a vacuum at the producer of from #b in4 to #d in4 of mercury will be sufficient4 ,for this work1 the multi-stage or even single-stage centrifugal fan is practically as efficient as the two-impeller rotary1 and will be lower in first cost and cost of maintenance4 ,either of the above mentioned vacuum producers are satisfactory for operating a system of this type4 ,control4--,every system of more than one-sweeper capacity in which a displacement type of exhauster is used should be provided with some means of economically controlling the vacuum at the producer4 ,on one-sweeper plants an automatic starter which will stop the motor when the vacuum reaches a point #b in4 above that required and start same when the vacuum drops to #a in4 below that required is convenient1 but not necessary4 ,for piston pumps and all other displacement pumps fitted with eduction valves1 an unloading device1 which closes the suction when the necessary vacuum is exceeded1 is the least expensive to install and gives very good economy when the demand on the plant is fairly continuous during the time it is in operation4 ,where the service is intermittent and required at nearly all hours1 the ,cutler ,hammer control1 described in ,chapter ,x1 is the most economical4 ,with displacement exhausters having no eduction valves1 the by-pass type of control is satisfactory where the service is continuous1 but is not as economical1 as the unloader used with producers having eduction valves and the ,cutler ,hammer control is more efficient under all conditions of service4 ,centrifugal exhausters need no control1 as vacuum control is an inherent feature of these machines4 ,summing up the subject1 we can divide the vacuum cleaning systems into four classes1 each of which requires a different selection of appliances4 ,they are as follows3 ,class #a4--,plant for residence or small office or departmental building1 to be not more than one-sweeper capacity4 ,renovators3 ,see list given for 8small volume0 plant1 ,chapter ,,iv4 ,hose3 #a-;in4 diameter4 ,separator3 ,centrifugal1 dry1 with bag or screen4 ,vacuum ,producer3 ,two impeller1 rotary1 alternate centrifugal fan4 ,capacity1 #cj cu4 ft4 of free air per minute1 #d in4 vacuum at producer4 ,control3 ,automatic starter1 operated by vacuum4 ,size of motor3 to #a ,h4 ,p4 ,class #b4--,large office or departmental building where carpet cleaning is important and pipe lines are of reasonable length4 ,renovators3 ,see list given for 8large volume0 plant1 ,chapter ,,iv4 ,hose3 #a-;in4 diameter4 ,separator3 ,centrifugal1 dry1 with bag or screen4 ,vacuum ,producer3 ,two impeller1 rotary4 ,capacity1 #gj cu4 ft4 of free air per minute for each sweeper of plant capacity at #g in4 to #i in4 vacuum4 ,size of motor3 #b ,h4 ,p4 per sweeper capacity4 ,control3 ,cutler ,hammer4 ,class #c4--,large building or group of buildings where carpet cleaning is important and long lines of piping are necessary4 ,renovator3 ,see list for 8large volume0 plants1 ,chapter ,,iv4 ,hose3 #a-;in4 diameter4 ,separators3 ,one centrifugal dry and one wet4 ,vacuum ,producer3 ,piston type pump4 ,capacity1 #de cu4 ft4 of free air per minute for each sweeper of plant capacity at #ad in4 vacuum4 ,size of motor3 #d ,h4 ,p4 for each sweeper of plant capacity4 ,control3 ,automatic unloader for continuous service4 ,cutler ,hammer for intermittent work at all times4 ,class #d4--,large or small plant where carpet cleaning is not an important function of the cleaning system4 ,renovators3 ,same as for ,class #c4 ,hose3 #a in4 or #a- in4 ,separators3 ,one centrifugal1 dry1 with or without bag1 according to type of exhauster adopted4 ,vacuum ,producer3 ,centrifugal fan or two-impeller rotary pump4 ,capacity3 #gj to #ij cu4 ft4 of free air per minute for each sweeper of plant capacity1 with a vacuum of from #b in4 to #c in4 mercury4 ,size of motor3 #a to #b ,h4 ,p4 for each sweeper of plant capacity4 ,control3 ,with centrifugal fan1 none2 with pump1 ,cutler ,hammer4 ,it is interesting to note that to produce the most efficient plant for all of the four cases named1 all of the various types of vacuum cleaning systems which have come into general use have to be operated each under its most favorable conditions and the engineer should select his plant to best fulfill the conditions of the special case at hand1 just as he would select his prime mover for an electric generating plant according to its size and location4 ,there should be no more reason why any one of these systems should attempt to fulfill the requirements of every installation than there would be for a manufacturer of steam engines to attempt to use the same type of engine to drive a generator under all conditions4 ,the writer believes that this condition will soon be realized by all manufacturers of vacuum cleaning systems and that they will endeavor to install apparatus of the type best suited to the conditions to be met in each case4 ,,chapter ,,xiii4 ,,tests4 ,having decided on the type of vacuum cleaning system that is best suited to the conditions of the particular building in which it is to be installed1 it then becomes necessary to ascertain what are the tests necessary to determine whether the installation will produce the desired results4 ,if the installation is one in which carpet cleaning is important and the plant is of more than one-sweeper capacity1 the exhauster must be of sufficient capacity to produce a vacuum of not less than #d in4 mercury at a carpet renovator attached to any inlet on the piping system1 when the plant is operating other renovators of any type attached to any of the other inlets corresponding to one less than the total sweeper capacity of the system4 ,when hose lengths as short as #be ft4 can be used on any or all of the outlets1 it has been demonstrated in ,chapter ,,vii that an air removal of #gj cu4 ft4 of free air per minute for each sweeper of plant capacity is necessary1 no matter what size of hose is used4 ,it was also shown that where pipe lines are very long and it is possible to always use #ajj ft4 of hose1 efficient cleaning can be done with less expenditure of power with an air displacement of #de cu4 ft4 of free air for each sweeper of plant capacity4 ,many methods have been recommended for testing a cleaning plant4 ,perhaps the earliest was the maintaining of #ae in4 of vacuum at the vacuum producer with carpet renovators each attached to #ajj ft4 of hose1 equal in number to the sweeper capacity of the plant in operation on carpets4 ,another test is to attach #ajj-;ft4 lengths of hose to inlets on the system1 with the ends wide open1 equal in number to the sweeper capacity of the plant1 and require the pump to maintain a vacuum of #ae in4 mercury4 ,both of these tests were recommended for use on plants where #a-;in4 diameter hose was provided and the results are dependent largely on the size and length of the piping system4 ,with an average-sized system1 the first test will require an exhaustion of approximately #be cu4 ft4 of free air per renovator per minute if ,type ,a renovators are used4 ,the second test wall require an exhaustion of approximately #ej cu4 ft4 of free air per open hose per minute4 ,neither of these tests will insure a plant of sufficient capacity to do effective cleaning where #be-;ft4 lengths of #a-;in4 hose can be used or if larger bore than #a-;in4 hose be used4 ,if these tests are required with bores larger than #a-;in4 diameter and the vacuum is maintained the same as before1 air exhaustion with #a-;in4 open hose will be approximately #gj cu4 ft4 of free air per open hose1 and with #a-;in4 hose1 approximately #aej cu4 ft4 per open hose1 while1 if carpet renovators be used1 the vacuum at the renovator would be from #g to #i in4 of mercury4 ,in either case1 the vacuum required to be maintained at the separators is higher than is necessary to produce economical cleaning with either #a-;in4 or #a-;in4 hose4 ,tests with carpet renovators attached to #ajj ft4 hose lines in number equal to the capacity of the plant1 and a vacuum of #d in4 of mercury at the renovator will result in an exhaustion below that necessary to produce efficient cleaning when bare floor renovators and carpet renovators with shorter hose lines are used1 as is likely to occur in actual practice4 ,again1 open hose tests require a variable length of hose to be used in order to obtain the same air quantity with the proper vacuum at the separator for economical operation4 ,if #gj cu4 ft4 of air is desired1 as in the case of ,class #b plant 7,chapter ,,xii71 the hose lengths should be3 #ej ft4 #a in4 diameter4 #ab in4 vacuum at separator4 #ge ft4 #a in4 diameter4 #i in4 vacuum at separator4 #abe ft4 #a in4 diameter4 #f in4 vacuum at separator4 ,any of these lengths would give satisfactory cleaning with one carpet renovator in use1 together with sufficient bare floor renovators to equal the capacity of the plant4 ,this is a possible condition in any plant4 ,another method of testing is to measure the actual air passing through a given length of hose and require sufficient vacuum at the separator to produce this flow4 ,this method is open to the objection that variation in the size of the hose will result in considerable variation in the vacuum at the separator and conditions of hose lengths may be such that when carpet renovators are attached to the hose1 the vacuum at the renovator will vary according to the resistance offered to the passage of the air by the friction in the hose4 ,with the small hose1 the friction will be greatest1 and the reduction in the quantity of air passing the renovator from that passing an open hose will result in the greatest reduction in friction loss through the hose and produce the highest vacuum at the renovator4 ,this will cause a widely different vacuum at the renovator with different sizes of hose1 each of which passes the same amount of air with the end of hose open4 ,what is desired in cleaning operations is a certain degree of vacuum at the carpet renovator1 with the system operated under the same conditions that will obtain in practical cleaning1 and with cleaners of various types attached to hose ends equal in number to the capacity of the plant4 ,the most rational system of testing is one in which the actual conditions of air quantity and vacuum are measured at the hose ends4 ,this can be obtained by actually attaching cleaning tools to the hose ends and measuring the vacuum within the renovator4 ,however1 a wide variation in vacuum will result when the renovator is moved along the carpet1 and this variation will be different with different operators and different grades of carpet to such an extent as to render it impossible to actually meet any requirements that may be specified1 unless a considerable variation in vacuum is permitted4 ,it is also possible for an operator to become so expert in the manipulation of the renovators as to be able to meet the specification requirements with a plant which will not give satisfactory results in actual operation4 ,the most satisfactory method of testing that has been devised is the use of an orifice of proper size fixed to the hose end and measure the vacuum just inside of this orifice4 ,in making such measurements care must be taken that the tube connecting to the vacuum gauge is not inserted in such a manner that the air velocity affects the reading of the vacuum gauge4 ,the shape of orifice must also be carefully specified1 as the rounding of the edges of the opening will greatly increase the quantity of air passing a given-sized orifice4 ,the best standard is a sharp-edged orifice in a thin disk which has a coefficient of ingress of approximately #fe4 ,illustration3 ,,fig4 #ajd4 ,,vacometer ,,for ,,use ,,in ,,testing ,,vacuum ,,cleaning ,,systems4 ,a convenient form of testing appliance based on the orifice test is the vacometer1 manufactured by the ,spencer ,turbine ,cleaner ,company and shown in ,fig4 #ajd4 ,this device consists of a spherical aluminum casting1 with a #a-;in4 diameter hole on the equatorial circle1 a vacuum gauge being attached to one polar extremity1 the other being attached to the end of the hose4 ,a ring having a slip fit is placed around the equatorial circle in which openings varying from -in4 to -in4 diameter are drilled4 ,by turning this ring any of the orifices may be made to register with the opening in the sphere4 ,the opening to which the vacuum gauge is attached is so located that it is not affected by the entering air current1 and its readings are not affected by the velocity head4 ,experiments with this instrument in connection with a ,pitot tube show that a -in4 diameter orifice is equivalent to a ,type ,a carpet renovator1 a -in4 orifice to a ,type ,f renovator and a -in4 orifice to a bare floor renovator4 ,with instruments of this type equal in number to the capacity of the plant in sweepers1 attached to the ends of the cleaning hose1 it is possible to obtain uniform conditions equal to the average results that will be obtained in actual practice with renovators attached to the hose1 without the possibility of expert manipulation of the renovators affecting the results4 ,the proper orifice to be used in each vacometer during the test will vary with the character of the service for which the plant is designed1 and the author recommends the following for each of the classes of plants described in ,chapter ,,xii3 ,class #a4 #b-;in4 mercury1 with -in4 orifice1 maximum length of hose to be used in actual cleaning4 ,class #b4 ,one-half the inlets -in4 orifice1 #d4e in4 mercury at one orifice attached at end of longest hose desired to use in practice1 the remaining -in4 outlets on shorter hose lengths4 ,the other half of inlets to have -in4 orifices open at same time1 with longest hose on one-quarter of total inlets and shortest on the balance4 ,class #c4 ,all inlets on long hose1 one-half with -in4 orifice1 balance with -in4 ,class #d4 ,all inlets to have -in4 orifice and #a in4 vacuum at vacometer1 all hose lines maximum length4 ,,chapter ,,xiv4 ,,specifications4 ,before the engineer begins to prepare his specifications for a proposed vacuum cleaning system1 he will naturally consider carefully the conditions to be met in the particular installation contemplated4 ,having considered these conditions1 he can readily determine the type of system that will operate most efficiently and economically under such conditions4 ,it is1 therefore1 natural to assume that the best interests of his clients can be obtained by confining his specifications to apparatus of the type giving the most efficient results for the special conditions to be met4 ,however1 it is also necessary to study the apparatus on the market to determine if there is a sufficient number of manufacturers producing the particular type of apparatus specified to insure healthy competition and reasonable bids4 ,it becomes necessary1 therefore1 to examine the various systems offered by the manufacturers in order to determine what competition can be obtained4 ,apparatus for ,class #a or ,class #b1 if confined to the positive displacement rotary exhausters of the two-impeller type1 can be obtained from at least seven manufacturers4 ,if the centrifugal fan is included1 at least three other manufacturers can be considered and in either case a healthy competition be had4 ,if apparatus of ,class #c is desired1 it can be obtained from at least three manufacturers4 ,a few years ago more manufacturers of systems of this type were in the market4 ,some of these have dropped out1 owing to the comparatively limited field for this apparatus4 ,however1 there are still enough manufacturers in the field to insure competition4 ,apparatus of ,class #d has been especially manufactured by one company4 ,however1 any of the manufacturers of centrifugal fan type of apparatus can easily meet the specification requirements for apparatus of the character4 ,it is1 therefore1 evident that the specification of apparatus of the type best suited to any particular installation will not result in lack of competition1 and such a procedure would apparently be justified4 ,there are installations1 such as those for public buildings1 where it may be advisable from an administrative standpoint to allow the widest competition possible4 ,in such cases the engineer can secure the best results for his clients by so drawing his specifications as to include all types of apparatus1 fixing carefully the test requirements to be met and requiring each bidder to state in his proposal the amount of power required to operate his apparatus under full load1 three-quarter load and half-load conditions1 and to base the award of the contract on an evaluation basis4 ,to determine what the basis of this evaluation shall be it is first necessary to ascertain the length of time the plant will be operated at each of the loads specified and find the annual cost of a unit of power to operate the plant4 ,assuming the plant has a life of ten years1 we can charge #aj depreciation1 add to this #e for interest on the investment and #a for insurance4 ,we can capitalize the saving in power at #af and use this amount as a basis for evaluation4 ,as an example1 assume one bidder guarantees a power consumption of #a ,k4 ,w4 less at full load1 #a4be ,k4 ,w4 less at three-quarters load and #j4ge ,k4 ,w4 more at half load than a lower bidder4 ,assume the plant will operate #ejj hrs4 per year at full load1 #bjj hrs4 at three-quarters load and #cjj hrs4 at half load4 ,the total kilowatt hours saved by the more economical plant will be3 ,full load #ejj #a #ejj ,three-quarter load #bjj #a4be #bej --- ,total saving #gej ,one-half load1 #cjj #j4ge #bbe --- ,net saving 7,k4 ,w4 ,hr47 #ebe ,if power costs #e cents per ,k4 ,w4 ,hr4 the yearly saving will be #bf4be1 which1 capitalized at #af1 will equal #afd4jj4 ,this is the amount which the owner would be justified in paying for the more economical plant above the price asked for the cheaper1 but less economical1 system4 ,in order to guard against any bidder guaranteeing a lower power consumption than he can actually show on test1 it is necessary to impose a penalty for failure to meet the guarantee which is in excess of the increase in price shown to be justified by the evaluation4 ,the author recommends that this penalty be made not less than #aej of the increase in price shown by the evaluation4 ,actually1 the owner will not lose by the less efficient plant any more than the amount shown by the evaluation if he junks the plant at the end of ten years4 ,however1 it is more than likely that he will either use it for a longer time or will be able to realize something for the plant when it is displaced4 ,the increased penalty1 therefore1 is justified1 and it is absolutely necessary to make this penalty greater than the increased value to prevent the bidder guaranteeing a power consumption lower than he can show on test4 ,the following pages contain sample specifications for apparatus of each of the four classes of systems described in ,chapter ,,xii and a specification permitting the widest competition1 with evaluation and penalty clauses4 ,,class #a ,,plant ,,for ,,residence ,,or ,,small ,,office ,,building ,,of ,,one-,,sweeper ,,capacity4 #a4 ,general ,description4 ,the work included in this specification shall be the installation of a complete vacuum cleaning system for the removal of dust and dirt from rugs1 carpets1 floors1 stairs1 furniture1 shelves1 walls and other fixtures and furnishings throughout the building1 and for conveying said dust and dirt to suitable receptacles located where shown1 together with all of the necessary cleaning tools1 hose1 piping1 separators1 exhauster1 motor1 etc41 as hereafter more fully specified4 #b4 ,exhauster4 ,the exhauster in all of its details shall be made of the best materials suitable for the purpose and shall be of approved design and construction1 and may be either of the positive displacement 7rotary7 or of the multi-stage fan type4 #c4 ,rotary ,exhauster4 ,the rotary displacement exhauster shall be either of the two-impeller type or of type having single impeller without sliding vanes revolving without friction contact with case and with oscillating follower4 #d4 ,exhausters fitted with sliding blade or blades will not be acceptable4 #e4 ,all parts of the exhauster shall be rigid enough to retain their shape when the machine is working under maximum-load conditions4 #f4 ,the impellers must be machined all over and must be of such shape and size that they will revolve freely and not touch each other1 the follower1 or the casing 7cylinder7 in which they are placed1 but the clearance must be of the least possible amount consistent with successful operation4 #g4 ,the shafts must be of steel with the journals ground to size4 #h4 ,the journal boxes must be long and rigidly supported by the headplates and placed far enough from the headplates to allow the placing of proper stuffing boxes on the shafts4 #i4 ,the shafts of two impeller exhausters must be connected by wide-faced steel gears1 cut from the solid and securely fastened to the shafts4 ,follower shaft on single impeller exhauster to be connected to impeller shaft by crank and connecting rod4 ,the gears shall run in suitable oil-tight gear boxes that shall be fitted with adequate and suitable means for lubrication4 #aj4 ,centrifugal ,fan ,type4 ,the centrifugal fan exhauster to be so proportioned and constructed as to handle the volume of air required at the specified vacuum with the least possible loss4 ,the housing shall be of cast iron or aluminum1 made in sections4 ,the housing must be air-tight4 #aa4 ,the fan wheels to be constructed of steel or other metal of high tensile strength1 properly reinforced1 and1 if cast1 must include hub and arms complete in one piece4 ,if the fan wheels are built up1 they must be strongly riveted to cast-iron1 steel or brass hubs or spiders4 #ab4 ,the fan wheels are to be secured to shaft with a feather and set screws1 or with left-hand screw4 #ac4 ,the shaft of fan exhauster may be vertical and the wheels so mounted that their weight will equalize or partly equalize the end thrust1 or the end thrust may be balanced by the magnetic pull of the armature4 ,shaft may be horizontal and end thrust taken care of with ball-bearing thrust rings4 #ad4 ,the journal boxes for all of the above named types of exhausters shall be of the design best adapted for the purpose and must be fitted with first-class approved continuous lubricating devices1 either sight feed1 ring oiler1 or any other kind best suited for the work or design of apparatus used4 #ae4 ,cooling4 ,the rotary type of exhauster must be provided with the necessary water connections to properly seal and cool the pump4 ,fan type of exhauster must be designed to operate continuously without a rise of temperature over #ajj ,f4 above room temperature4 #af4 ,speed4 ,rotary exhausters shall not exceed a peripheral speed of #a1ajj ft4 per minute at tips of impellers4 #ag4 ,centrifugal fans shall not exceed peripheral velocity of #bb1jjj ft4 per minute when running under specified full-load conditions4 #ah4 ,mounting4 ,the exhauster1 motor and separators shall be mounted as a unit on suitable cast-iron base plate1 either mounted on legs or resting on the basement floor4 #ai4 ,drive4 ,the exhauster shall be driven by an electric motor1 which may be direct connected to the exhauster shaft or be operated with an oak-tanned leather belt1 or by cut gearing4 ,belt and gearing are to be of ample size and strength for their work and must run without undue noise or wear4 ,means shall be provided to take up the slack of the belt4 ,furnish and place a suitable metal guard over belt and pulley wheels that shall prevent oil being splashed outside of the base plate and prevent clothing being caught4 #bj4 ,if the exhauster is operated through cut gearing1 the gearing must be inclosed in an oil and dust proof case1 which shall be fitted with means for copious and continuous lubrication of same4 #ba4 ,finish4 ,the air exhauster and motor and the base plate shall be finished in a first-class manner1 filled1 rubbed down and painted at least one coat at the shop1 and after installation shall receive two more coats1 finishing tint to be as directed4 #bb4 ,electric ,motor4 ,motor to be of such size that when operating under test conditions it will not be under less than three-fourths nor more than full-load condition4 ,it is to be of standard make1 approved by the architect4 #bc4 ,motor to be wound for 4444 volts direct current4 #bd4 ,armature to be of toothed-core construction1 with windings thoroughly insulated1 and securely fastened in place1 and must be balanced both mechanically and electrically4 #be4 ,commutator segments must be of drop-forged or hard-drawn copper of highest conductivity1 well insulated with mica of even thickness and proper hardness to insure uniform wear1 and shall run free from sparking or flashing at the brushes under all conditions of speed4 ,it must be free from all defects and have ample bearing surfaces and radial depth as provision for wear4 #bf4 ,brushes to be of carbon1 mounted on a common rocker arm for motor1 and to have cross-sectional area of not less than #a square inch for each #ce amperes of current4 #bg4 ,brush holders to be of a design to prevent chattering1 with individual adjustment in tension for each brush4 #bh4 ,bearings to be of an approved self-oiling or ring type4 #bi4 ,there must be an insulation resistance between motor frame and field coils1 armature windings and brush holders of not less than #a megohm4 #cj4 ,motor must be capable of standing a breakdown test of #a1ejj volts alternating current4 ,either or both of the foregoing tests to be applied at the discretion of the architect's agent at the time of shop tests4 #ca4 ,the maximum rise in temperature of the motor at a continuous run 7after installation at building7 at full speed and full-rated load for a period of eight hours must not exceed #ej ,c4 in windings and #ee ,c4 on commutator above the surrounding atmosphere4 #cb4 ,motor to be finished in a first-class manner1 filled and rubbed down and painted two coats at the shop1 and after installation to have two more coats2 finishing tints to be as directed by the superintendent of the building4 #cc4 ,tablet4 ,furnish and mount where directed a polished slate tablet not less than in4 thick1 having mounted thereon one #cj-;ampere1 #bej-volt1 double-pole knife switch1 with enclosed indicating fuses1 and1 if displacement exhauster is furnished1 one automatic self-starter having butt contacts1 cutting out starting resistance in not less than two steps1 starter to be controlled by the vacuum in separator1 and shall stop motor when vacuum rises #b in4 above that required to meet test requirements and start motor when vacuum falls to that required for working4 #cd4 ,electrical ,connections4 ,this contractor shall run feeders from vacuum cleaner panel in switchboard where shown to the motor panel and make all electrical connections between panel and motor1 etc4 #ce4 ,all wires are to be run in standard steel conduit1 except those that are so short as to be self-supporting1 and these are to be cord wrapped or otherwise protected4 ,no wire smaller than ,no4 #h to be used4 #cf4 ,all material and workmanship to be strictly first class4 ,electrical work must show an insulation resistance of at least #a megohm1 and to be in strict accordance with the latest edition of the 8,national ,electrical ,code40 #cg4 ,dust ,separator4 ,there shall be one dry separator located where shown on plans1 having a volume not less than #c cu4 ft4 #ch4 ,the interior arrangement of the separator shall be such that no part of same will receive the direct impact of the dust4 ,cloth bags or metal screens if used in this separator shall be so placed that nothing but the very lightest of the dust can lodge thereon1 and that same may be easily cleaned without dismantling the separator4 ,it must be so constructed that it shall intercept not less than #ie of the dust entering same4 #ch;a4 ,separator tank shall be constructed with steel shells1 with either cast iron or steel heads1 and be fitted with suitable bases or floor stands for support and proper openings for cleaning same4 ,separator shall be fitted with iron-column mercury gauge reading #ej in excess of operating vacuum4 #ci4 ,pipe ,lines4 ,all pipe lines shall be of the sizes and run as indicated on drawings4 #dj4 ,pipes4 ,all pipe conveying air is to be standard black wrought-iron or mild-steel screw-jointed pipe1 and is to be smooth inside1 free from dents1 kinks1 fins1 or burs4 ,ends of pipe to be reamed to the full inside diameter and beveled4 ,bent pipe to be used in mains where necessary and where shown on plans4 #da4 ,care must be taken in erecting pipe to maintain as nearly as possible a smooth1 uniform bore through all pipe and fittings4 #db4 ,fittings4 ,all fittings to be tough gray cast iron1 free from blowholes or other defects2 smooth castings in all cases4 #dc4 ,all fittings on vacuum lines must have inside diameter through body of same size as pipe bore1 and all fins1 burs1 or rough places must be removed4 #dd4 ,fittings on vacuum lines are to be black or may be galvanized4 #de4 ,where space permits1 all tees and elbows must have a radius at center line of not less than #c in4 #df4 ,horizontal overhead pipes to be supported with substantial pipe hangers spaced not more than #aj ft4 apart4 #dg4 ,the hangers must have an approved form of adjustment and the instructions of the superintendent in regard to securing hangers to floor construction1 etc41 above must be carefully followed4 #dh4 ,where exposed pipes pass through walls or floors of finished rooms they must be fitted with cast-iron nickel-plated plates4 #di4 ,clean-,out ,plugs4 ,brass screw-jointed clean-out plugs are to be provided in lines at all turns where indicated on the drawing4 ,the clean-out plugs to be #b in4 diameter1 except in the #a-;in4 lines1 where clean-outs are to be same diameter as the lines4 #ej4 ,exhaust ,connection4 ,exhaust pipe from the exhauster is to be run up to the basement ceiling and along same into the smoke breeching beyond damper as directed4 #ea4 ,sweeper ,inlets4 ,the following number of inlets are to be provided3 ,subbasement 1 basement 1 first story 1 second story 1 attic 4 #eb4 ,the sweeper inlets are to be fitted with hinged covers or caps with rubber gaskets arranged to be self-closing when hose is removed1 and those in corridors and lobby arranged to be opened with a key4 #ec4 ,inlets coming through finished walls or partitions are to be flush pattern4 #ed4 ,inlets on risers run exposed against walls are to be set close up against bead of fittings4 #ee4 ,if contractor desires to use other form of connection than above described which is equally satisfactory1 same must be submitted to the ,architect for approval after award of the contract4 #ef4 ,in this specification the word 8renovator0 is used to mean that portion of the tool which is in contact with the surfaces cleaned2 the word 8stem10 that portion connecting the renovator and hose2 the word 8cleaner0 is used to mean a complete cleaning tool4 #eg4 ,the following cleaning tools are to be furnished3 ,one carpet renovator1 with cleaning slot in4 by #ab in4 long4 ,one bare floor renovator1 #ab in4 long1 with curved felt-covered face4 ,one wall renovator1 #ab in4 long1 with cotton flannel curved face4 ,one upholstery renovator1 with slot in4 by #d in4 ,one corner cleaner4 ,one radiator cleaner4 ,one hat brush4 ,one long curved stem about #e ft4 long4 ,one extension tube about #e ft4 long4 #eh4 ,the renovators for carpets1 bare floors and walls to be arranged with adjustable swivel joint1 so that same can be operated at an angle with stem from #de for regular use to an angle of about #hj for use under or back of furniture and other similar places4 ,this movable joint to be so arranged that lips of cleaning tool will always remain in contact with surface cleaned1 and constructed so that fitted surfaces are not exposed to dust1 and the air currents when deflected to impinge only upon surfaces which are of heavy metal and where such wear as occurs will not affect the operation and handling of the tool4 #ei4 ,all renovators and stems are to be as light as is consistent with strength and ability to withstand cutting action of dust4 #fj4 ,the lips of carpet renovators and upholstery cleaner to be of such proportions and form as will prevent injury to the fabric1 and such widths as will reduce to a minimum the sticking of renovator face to the material being cleaned4 #fa4 ,stems to be not less than #a in4 outside diameter4 ,air passages in swivels to be same diameter as inside of stem4 ,stem for use with floor renovators shall be curved near upper end to form handle and provided with swivel to permit hose hanging vertical4 #fb4 ,stems to be drawn-steel or brass tubing1 not less than ,no4 #ba ,united ,states standard gauge thick if steel and not less than ,no4 #af ,brown ,sharpe gauge thick if brass4 #fc4 ,carpet renovators to be made preferably of pressed steel1 as light as possible1 or may be made of cast iron1 brass or aluminum with iron wearing face4 #fd4 ,bare floor renovators shall have renewable elastic wearing face curved in direction of motion when cleaning4 #fe4 ,all renovators and brushes must be provided with proper rubber or other approved buffers to prevent marring the woodwork4 #ff4 ,upholstery cleaners are to have inlet slots or openings of such size and form as to absolutely prevent drawing in loose covering of furniture4 #fg4 ,upholstery and corner cleaners are not to be arranged for use with stems1 but are to have their own handles permanently attached and be provided with hose couplings4 #fh4 ,all metal parts of renovators and stems are to be finished1 and all except aluminum parts nickel plated4 #fi4 ,hose4 ,furnish #ge ft4 cleaning hose in three #be-;ft4 lengths4 #gj4 ,the hose to be #a in4 inside diameter best quality rubber hose1 reinforced in best manner to absolutely prevent collapse at highest vacuum obtainable with the exhauster furnished and to prevent collapse if stepped on4 ,weight of hose to be not over #ab oz4 per linear foot4 #ga4 ,couplings for hose to be either slip1 bayonet-lock or all-rubber type1 with smooth bore of practically same diameter as inside of hose4 ,the couplings to have least possible projection outside of hose dimensions and be well rounded1 so as not to injure floors1 doors1 furniture1 etc4 #gb4 ,bayonet joints may have packing washer1 and slip joints to have permanent steel pieces on ends of hose and brass slip coupler4 ,all ends of hose at couplings to have outside ferrules securely fastened in place1 or pure gum ends glued to coupling4 ,simple conical slip joints slipped into ends of hose without ferrules will not be acceptable4 ,all joints must fit together so that they will not be readily pulled apart4 #gc4 ,tests4 ,all piping to be tested with air pressure equal to #e in4 mercury before being concealed in walls and other spaces4 ,mercury must not fall more than in4 in one-half hour4 #gd4 ,on completion of plant the pump will be operated with all outlets closed and1 under these conditions1 there must be an interval of not less than #aj min4 between the stopping and starting of the motor by the automatic control1 if pump system is used4 ,and if fan system be used1 the power required to operate the exhauster must not be more than #fe that required in capacity test4 #ge4 ,to test the capacity of the separator1 a mixture containing #f lbs4 of sand1 passed through a #ej-mesh screen1 #c lbs4 of common wheat flour and #af lbs4 of ,portland cement shall be spread over #ej sq4 ft4 of floor and picked up with a renovator attached to the end of #ej ft4 of #a-;in4 hose4 ,the machine shall be stopped and the material removed from the separator spread on floor and picked up4 ,this procedure shall be repeated until the material has been handled four times4 ,if the separator contains a bag1 the same must not be disturbed until after completion of the capacity test1 which will be made with the material in place in separator1 after being picked up the fourth time4 ,after completion of capacity test1 the contents of separator shall be weighed and if same be a partial separator it must contain #ie of the material picked up4 ,if a displacement machine is used as a vacuum producer1 the separator must prevent the passage of any dust through separator1 which will be determined by holding a dampened cloth over pump outlet during test of apparatus4 ,said cloth must not show any dust lodged thereon at end of test4 #gf4 ,to test the capacity of the plant a standard vacometer1 attached to the end of #ge ft4 of cleaning hose shall show a vacuum of #b in4 mercury with -in4 diameter orifice open4 #gg4 ,test of ,cleaning ,tools4 ,the plant shall be operated by the ,contractor in the presence of the ,architect's representative1 and a test made of each kind of cleaning tool furnished4 ,the tool shall be attached to a #ej-;ft4 length of hose attached to an outlet selected by the ,architect's representative1 and under normal working conditions each tool must satisfactorily perform the work for which it was designed4 ,dust and surfaces to be cleaned shall be furnished by the contractor4 #gh4 ,painting4 ,after the completion of the specified tests1 all exposed iron work except galvanized iron or tinned work in connection with this apparatus1 not specified to be otherwise finished1 shall be primed with paint suitable for surfaces covered1 and then given two additional coats4 ,machinery shall be painted as already specified1 and all other work shall be given finishing tints as selected or approved by the architect4 ,black iron pipe1 etc41 shall be given two coats lead and oil of tint directed4 ,modifications of ,specifications when ,alternating ,current is ,available4--,when alternating current is available1 instead of direct1 modify specifications as follows3 #bc4 ,motor to be wound for 4444 volts1 4444 cycle1 4444 phase alternating current4 #bd4 ,motor to have rotor of the squirrel cage type4 ,omit #be1 #bf and #bg4 #bh4 ,to remain as for direct current4 #bi4 ,there must be an insulation between the starter or primary windings and the frame of not less than one megohm4 #cj1 #ca1 and #cb4 ,same as for direct current4 #cc4 ,tablet4 ,furnish and mount where directed a polished slate tablet having mounted thereon a #cj ampere1 #bej volt1 4444 pole knife switch with enclosed indicating fuses and1 if displacement type exhauster is furnished1 an automatic starter of the 8across the line0 type1 operated by vacuum in the separator which will stop motor when the vacuum in the separator rises #b in4 above that required to meet test conditions1 and start exhauster when vacuum reaches working range4 ,,class #b ,,plant ,,for ,,large ,,office ,,building ,,having ,,pipe ,,lines ,,of ,,moderate ,,length4 #a4 ,same as for ,class #a4 #b4 ,omit centrifugal fan4 #c to #i4 ,same as for ,class #a4 ,omit #aj to #ac4 #ad and #af4 ,same as for ,class #a4 #ae4 ,omit centrifugal fan4 ,omit #ag and #ah4 #ah;a4 ,base ,plate1 ,foundation1 etc4 ,provide suitable base plate to rigidly support the exhauster and its motor as a unit1 which shall be large enough to catch all drip of water or oil4 ,provide a raised margin and pads for feet of exhauster frame1 motor1 and anchor bolts1 high enough to prevent any drip from getting into the foundation or on the floor4 #ah;b4 ,provide suitable foundation of brick or concrete1 to which the base plate shall be firmly anchored4 ,the foundation shall be built on top of the cement floor of the basement1 which shall be picked to afford proper bond for the foundation4 #ah;c4 ,construct the foundation of such a height as to bring the working parts of the machine at the most convenient level for operating purposes4 ,exposed parts of the foundation to be faced with best grade white enameled brick4 ,if the base plate does not cover the foundation1 the exposed top surface is to be finished with enameled brick1 using bull-nose brick on all edges and corners4 #ai to #bc4 ,same as for ,class #a4 #bc;a4 ,the guaranteed efficiency of motor shall not be less than #gh at half load and not less than #hd at full load4 #bd to #cb4 ,same as for ,class #a4 #cb;a4 ,motor shall be subject to shop test to determine efficiency1 heating1 insulation1 etc4 ,manufacturer's certified test sheets of motor giving all readings taken during shop tests1 together with calculated results1 must be submitted to the ,architect for approval before motor is shipped from factory4 #cc4 ,rheostat4 ,furnish and install where shown1 upon a slate panel hereinafter specified1 a starting rheostat of proper size and approved made1 designed for the particular duty it has to perform4 ,it must have an automatic no-voltage and overload release4 ,all resistance for rheostat is to be placed on the back of the tablet4 ,contacts must project through board to front side4 ,all moving parts must be on front of board4 #cc;a4 ,tablet4 ,furnish and place where shown1 a slate tablet not less than in4 thick1 supported by a substantial angle iron frame1 so placed that there will be a space of not less than #d in4 between the wall and back of resistance4 ,mount on this tablet one double-pole1 #bej-volt knife switch1 with two #bej-volt inclosed fuses and one starting rheostat1 as specified hereinbefore4 ,the connections shall be on the back of the tablet4 ,the space between the column and the tablet shall be inclosed with a removable diamond-mesh grill of ,no4 #aj iron wire in channel frame4 #cd1 #ce1 #cf4 ,same as for ,class #a4 #cf;a4 ,automatic ,control4 ,suitable means shall be provided in connection with the rotary exhausters that will maintain the vacuum in the separators within the limit of the machine at point found to be most desirable1 irrespective of the number of sweepers in operation4 #cf;b4 ,controller shall consist of a suitable means provided in the exhauster1 or as an attachment thereto1 which will automatically throw the exhauster out of action by admitting atmospheric pressure to the exhauster only1 but not to the system whenever the vacuum in the separators rises above the point considered desirable1 and throw the exhauster into action when the vacuum falls below the established lower limit4 #cf;c4 ,vacuum ,breaker4 ,in addition to the controlling devices above specified there shall be placed in the suction pipe to the exhauster an approved positive-acting vacuum breaker having opening equivalent to the area of #a-;in4 diameter pipe and set to open at #aj inches vacuum4 7,if plant is to be run for long periods without much load1 as in a hotel1 omit #cf;a1 b1 c1 and substitute73 #cf;d4 ,automatic ,control4 ,an approved type of controller for maintaining practically a constant vacuum by varying the speed of the motor driving exhauster arranged to permit the operation of the motor continuously at any speed between full speed and stop1 so long as there be no change in vacuum and which will increase speed whenever vacuum falls and reduce speed whenever vacuum rises1 must be provided4 #cg4 ,dust ,separator4 ,there shall be one dry separator located where shown on plans1 having a volume of not less than #c cu4 ft4 for each sweeper of plant capacity4 #ch4 ,the interior arrangement of the separator shall be such that no part of same will receive the direct impact of the dust4 ,cloth bags or metal screens1 if used in this separator1 shall be so placed that nothing but the very lightest of the dust can lodge thereon1 and that same may be easily cleaned without dismantling the separator4 ,it must be so constructed that it will intercept all of the dust entering same4 #ch;a to #ef4 ,same as for ,class #a4 #ef;a4 ,tool ,cases4 ,furnish approved hardwood cabinet-finished cases for cleaning tools4 ,each case to be made as light as possible and of convenient form for carrying by hand and provided with a complete set of cleaning tools1 each securely held in its proper place1 and fitted with lock and key1 clamps1 and conveniently arranged handles4 #eg4 ,each case shall contain the following3 ,one carpet renovator1 with slot in4 by #ae in4 ,one bare floor renovator1 #ae in4 long1 with curved felt-covered face4 ,one wall brush1 with skirted bristles1 #ab in4 long and in4 wide4 ,one hand brush1 with hose connections at end1 #h in4 long1 #b in4 wide4 ,one #d-;in4 round brush for relief work4 ,one upholstery renovator4 ,one corner cleaner4 ,one radiator tool4 ,one curved stem about #e ft4 long4 ,one extension tube #e ft4 long4 ,at least one hat brush with the system4 #eh to #fd4 ,same as for ,class #a4 #fd;a4 ,all brushes to be of substantial construction1 with best quality bristles set in close rows and as thick as possible1 skirted with rubber1 leather1 or chamois skin1 so that all air entering renovator will pass over surface being cleaned4 #fe to #fh4 ,same as for ,class #a4 #fi4 ,hose ,racks4 ,furnish and properly secure in place1 where directed1 4444 hose racks in basement1 4444 each in first and second stories 74444 racks in all74 ,the racks to be constructed of cast iron1 galvanized or enamel finish1 and each rack to be suitable for holding #ge ft4 of hose of required size4 #fi;a4 ,hose4 ,there must be furnished with each hose rack #ge ft4 of noncollapsible hose in three #be-;ft4 lengths4 #gj to #gc4 ,same as for ,class #a4 #gd4 ,on completion of the plant the pump will be operated with all outlets closed1 and1 under this condition1 the power consumption must not be more than #ej of that required under test conditions4 #ge4 ,test of ,separators4 ,at each of ---- points1 near ---- outlets on different risers selected by the architect's representative1 the contractor shall furnish and spread on the floor1 evenly covering an area of approximately #ej sq4 ft4 for each outlet1 a mixture of #f lbs4 of dry sharp sand that will pass a #ej-mesh screen1 #c lbs4 of fine wheat flour and #f lbs4 of ,portland cement4 #ge;b4 ,fifty feet of hose shall be attached to each of the ---- outlets1 and the surfaces prepared for cleaning shall be cleaned simultaneously by operators provided by the contractor until all of the sand1 flour and ,portland cement has been taken up1 when the exhauster shall be stopped and the dirt removed from the separator and spread on the floor again1 and the operation of cleaning repeated until the mixture has been handled by the apparatus four times4 ,the bag contained in the separator must not be disturbed until after completion of the capacity test1 which will be made with material in place in the separator after being picked up the fourth time4 ,after completion of the capacity test the contents of separator will be removed4 ,during test of separators a dampened cloth will be held over the exhaust from pump4 ,if such cloth indicates dirt passing through the separator1 same will be rejected4 #gf4 ,to test the capacity of the plant1 one hose line #ajj ft4 long shall be attached to inlet farthest from the separator with standard vacometer1 with -in4 opening in end of hose4 4444 hose lines shall be attached to other outlets1 each with #ej ft4 hose and vacometers in end of hose1 4444 vacometers having -in4 opening and 4444 vacometers having -in4 opening4 ,under these conditions #d in4 mercury must be maintained in vacometer at end of #ajj ft4 of hose4 #gg and #gh4 ,same as for ,class #a4 ,modifications of ,specifications when ,alternating ,current is ,available4--,when alternating current is available1 instead of direct1 modify specifications as follows3 #bc4 ,motor to be wound for 4444 volts1 4444 cycle1 4444 phase alternating current4 #bc;a4 ,bidders must name efficiency and power factor of motor at one-half and full load4 #bd4 ,motor to have phase-wound rotor with collector rings for insertion of starting resistance4 ,omit #be1 #bf and #bg4 #bh4 ,same as for direct current4 #bi4 ,there must be an insulation between the starter or primary windings and the frame of not less than one megohm4 #cj1 #ca1 #cb1 #cb;a4 ,same as for direct current4 #cc4 ,rheostat4 ,furnish and install an approved hand-starting rheostat for inserting resistance in rotor circuit in starting1 of proper size to insure the starting of motor in not exceeding #ae seconds without overheating4 #cc;a4 ,same as for direct current1 except that switch must be either three- or four-pole1 according to current available4 ,omit #cf;d with alternating current machine4 ,,class #c ,,large ,,installation ,,with ,,unusually ,,long ,,pipe ,,lines4 #a4 ,same as for ,class #a4 #b4 ,exhauster shall be of the reciprocating piston type4 #c4 ,the piston type of exhauster shall be double acting and so designed that the cylinder clearance shall be reduced to a minimum1 or suitable device shall be employed to minimize the effect of large clearance4 #d4 ,the induction and eduction valves may be either poppet1 rotary1 or semi-rotary1 and shall operate smoothly and noiselessly4 #e4 ,the piston packing shall be of such character as to be practically air tight under working conditions and constructed so that it will be set out with its own elasticity without the use of springs of any sort4 ,if metallic rings are used1 they must fill the grooves in which they are fitted1 both in width and depth1 and must be concentric2 that is1 of the same thickness throughout4 ,the joint in the ring or rings to be lapped in width but not in thickness1 and if more than one ring is used they are to be placed and doweled in such position in their respective grooves so that the joints will be at least one-fourth of the circumference apart4 #f4 ,the piston shall have no chamber or space into which air may leak from either side of the piston4 ,all openings into the body of the piston must be tightly plugged with cast-iron plugs4 #g4 ,the piston rod stuffing box to be of such size and depth that if soft packing is used it can be kept tight without undue pressure from the gland4 ,if metallic packing is used1 it must be vacuum tight without undue pressure on the rod4 ,proper means shall be provided for the continuous lubrication of the piston rod4 #h4 ,the exhauster of the piston type shall be fitted with an approved cross-head suitably attached to the piston rod2 machines having an extended piston rod for guide purposes will not be acceptable4 ,omit #i to #ac4 #ad4 ,same as for ,class #a4 #ae4 ,reciprocating piston exhauster shall be provided with the necessary devices for the removal of the heat generated by friction and compression1 that shall prevent the temperature of cylinders or eduction chambers rising more than #ajj ,f4 above the surrounding atmosphere after two hours' continuous operation under full-load conditions4 #af4 ,speed4 ,reciprocating exhauster with poppet valves shall operate at an average piston speed not exceeding #bjj ft4 per minute1 with rotary valves not exceeding #cjj ft4 per minute4 ,omit #ag and #ah4 #ah;a4 ,base ,plate1 ,foundation1 etc4 ,provide suitable base plate to rigidly support the exhauster and its motor as a unit1 which shall be large enough to catch all drip of water or oil4 ,provide a raised margin and pads for feet of exhauster frame1 motor1 and anchor bolts1 high enough to prevent any drip from getting into the foundation or on the floor4 #ah;b4 ,provide suitable foundation of brick or concrete1 to which base plate shall be firmly anchored4 ,the foundation shall be built on top of the cement floor of the basement1 which shall be picked to afford proper bond for the foundation4 #ah;c4 ,construct the foundation of such a height as to bring the working parts of the machine at the most convenient level for operating purposes4 ,exposed parts of the foundation to be faced with best grade white enameled brick4 ,if the base plate does not cover the foundation1 the exposed top surface is to be finished with enameled brick1 using bull-nose brick on all edges and corners4 #ai to #bc4 ,same as for ,class #a4 #bc;a4 ,the guaranteed efficiency of motor shall not be less than #hj at half load and not less than #he at full load4 #bd to #cb4 ,same as for ,class #a4 #cb;a4 ,motor shall be subject to shop test to determine efficiency1 heating1 insulation1 etc4 ,manufacturers' certified test sheets of motor1 giving all readings taken during shop test1 together with calculated results1 must be submitted to the ,architect for approval before motor is shipped from factory4 #cc4 ,rheostat4 ,furnish and install where shown1 upon a slate panel hereinafter specified1 a starting rheostat of proper size and approved make1 designed for the particular duty it has to perform4 ,it must have an automatic no-voltage and overload release4 ,all resistance for rheostat is to be placed on the back of the tablet4 ,contacts must project through board to front side4 ,all moving parts must be on front of board4 #cc;a4 ,tablet4 ,furnish and place where shown1 a slate tablet1 not less than in4 thick1 supported by a substantial angle bar frame1 so placed that there will be a space of not less than #d in4 between the wall and back of resistance4 ,mount on this tablet one double-pole1 #bej-volt knife switch1 with two #bej-volt inclosed fuses and one starting rheostat1 as specified hereinbefore4 ,the connections shall be on the back of the tablet4 ,the space between the column and the tablet shall be inclosed with a removable diamond-mesh grill of ,no4 #aj iron wire in channel frame4 #cd1 #ce and #cf4 ,same as for ,class #a4 #cg4 ,dust ,separators4 ,there shall be one dry and one wet separator located where shown on drawings4 ,each separator shall have a volume of #c cu4 ft4 for each renovator of plant capacity4 #ch4 ,the separator first receiving the dust shall be a dry separator1 the interior arrangement of which shall be such that no part of same shall receive the direct impact of the dust4 ,no screens or cloth bags shall be used in this separator and it must be so constructed that it will intercept #ie of the dust entering same4 #ch;a4 ,the second separator must be a wet separator which may be contained in the base of the machine or consist of a separate tank4 #ch;b4 ,wet separators1 whether separate from or integral with the base of the machine1 must be provided with an attachment which will positively mix the air and water1 thoroughly break up all bubbles1 separate the water from the air1 and prevent any water entering the exhauster cylinder4 #ch;c4 ,suitable means must be provided to automatically equalize the vacuum between wet and dry separators upon the shutting down of the exhauster4 #ch;d4 ,the separators must be provided with suitable openings for access to the interior for inspection and cleaning1 and the interior arrangement of the separators must be such that they may be readily cleaned without dismantling4 #ch;e4 ,all parts of the wet separator tank not constructed of non-corrosive metal must be thoroughly tinned or galvanized both inside and outside4 ,the interior of the wet separator formed in base of exhauster shall be painted with at least two coats of asphalt varnish or other paint suitable to prevent the corrosion of same4 #ch;f4 ,separators must be provided with all necessary valves or other attachments for successful operation1 including a sight glass for the wet separator1 through which the interior of the same may be observed1 and an iron-case mercury column reading #ej in excess of operating vacuum1 attached to the dry separator first receiving the dust4 #ch;g4 ,the wet separator shall be properly connected to water supply where directed and discharge to sewer where shown on plans4 #ch;h4 ,a running trap with clean-out shall be installed in the waste line4 #ci to #da4 ,same as for ,class #a4 #da;a4 ,waste and water pipe1 in connection with wet separator and jacket1 except waste pipe below basement floor1 to be standard galvanized wrought-iron pipe or steel screw-jointed pipe free from burs4 ,waste pipe below the basement floor is to be best grade1 8extra heavy0 cast-iron pipe1 with lead-calked joints4 #db to #de4 ,same as for ,class #a4 #de;a4 ,fittings on water lines to be standard galvanized beaded fittings4 #de;b4 ,fittings on waste line above basement floor line to be galvanized recessed screw-jointed drainage fittings and those below basement floor to be 8extra heavy0 cast-iron with hub joints4 #df to #ej4 ,same as for ,class #a4 #ej;a4 ,the exhaust pipe is to be fitted with an approved first-class exhaust muffler not less than #ab in4 in diameter and #fj in4 high1 closely riveted and constructed of galvanized iron not less than in4 thick1 and in event an exhauster requiring lubrication is furnished1 this muffler is to be arranged so that it will also be an efficient oil separator4 ,drip connection to be arranged at bottom of muffler4 #ea to #ef4 ,same as for ,class #a4 #ef;a4 ,tool ,cases4 ,furnish 4444 approved hardwood cabinet-finished cases for cleaning tools4 ,each case to be made as light as possible and of convenient form for carrying by hand and provided with a complete set of cleaning tools1 each securely held in its proper place1 and fitted with lock and key1 clamps and conveniently arranged handles4 #eg4 ,each case shall contain the following3 ,one carpet renovator1 with slot in4 by #ab in4 ,one bare floor renovator #ab in4 long1 with curved1 felt-covered face4 ,one wall brush1 with skirted bristles1 #ab in4 long and in4 wide4 ,one hand brush1 with hose connection at end1 #h in4 long and #b in4 wide4 ,one #d-;in4 round brush for relief work4 ,one upholstery renovator4 ,one corner cleaner4 ,one radiator tool4 ,one curved stem about #e ft long4 ,one straight extension stem #e ft4 long4 ,at least one hat brush with the system4 #eh to #fd4 ,same as for ,class #a4 #fd;a4 ,all brushes to be of substantial construction1 with best quality bristles set in close rows and as thick as possible1 skirted with rubber1 leather1 or chamois skin1 so that all air entering renovator will pass over surface being cleaned4 #fe to #fh4 ,same as for ,class #a4 #fi4 ,hose ,racks4 ,furnish and properly secure in place where directed1 4444 hose racks in basement1 4444 each in first and second stories 74444 racks in all74 ,the racks to be constructed of cast-iron1 galvanized or enamel finish1 and each rack to be suitable for holding #ge ft4 of hose of required size4 #fi;a4 ,hose4 ,there must be furnished with each hose rack #ge ft4 of non-collapsible hose in three #be-;ft4 lengths4 #gj4 ,hose to be #a in4 inside diameter of best quality1 rubber hose1 reinforced in best manner to absolutely prevent collapse at highest vacuum obtainable with the exhauster furnished and to prevent collapse if stepped on4 ,weight of hose to be not over #ab oz4 per linear foot4 #ga1 #gb and #gc4 ,same as for ,class #a4 #gd4 ,on completion of the plant the pump will be operated with all outlets closed and1 under this condition1 the power consumption must not be more than #ej of that required under test conditions4 #ge4 ,to test the capacity of the plant1 4444 hose lines each #ajj ft4 long will be attached to outlets on the system and each hose fitted with a standard vacometer4 4444 vacometers shall have -in4 opening and 4444 vacometers shall have -in4 opening4 ,under these conditions #d in4 vacuum must be maintained at vacometers having in4 opening4 #ge;a4 ,test of ,separators4 ,at each of ---- points1 near ---- outlets on different risers selected by the architect's representative1 the contractor shall furnish and spread on the floor1 evenly covering an area of approximately #ej sq4 ft4 for each outlet1 a mixture of #f lbs4 of dry sharp sand that will pass a #ej-mesh screen1 #c lbs4 of fine wheat flour1 and #a lb4 of finely pulverized charcoal4 #ge;b4 ,fifty feet of hose of size required by the system shall be attached to each of the ---- outlets1 and the surface or surfaces prepared for cleaning shall be cleaned simultaneously by operators provided by the contractor until all of the sand1 flour and charcoal has been taken up1 when the exhauster shall be stopped and the dirt removed from the dry separator and spread on the floor again1 and the operation of cleaning repeated until the mixture has been handled by the apparatus four times4 ,if1 after thoroughly flushing the system at completion of above run1 any dust or mud is found in the cylinder1 ports1 or valve chambers of the displacement exhauster1 or if less than #ie of the dirt removed is found in the dry separator1 it shall be deemed sufficient ground for the rejection of the separators4 #gf and #gg4 ,same as for ,class #a4 ,modifications of ,specifications when ,alternating ,current is ,available4--,when alternating current is available1 instead of direct1 modify specifications as follows3 #bc4 ,motor to be wound for 4444 volts1 4444 cycle1 4444 phase alternating current4 #bc;a4 ,bidders must name efficiency and power factor of motor at one-half and full load4 #bd4 ,motor to have phase-wound rotor with collector rings for insertion of starter resistance4 ,omit #be1 #bf and #bg4 #bi4 ,same as for ,class #a1 alternating current4 #cc4 ,rheostat4 ,furnish and install an approved hand-starting rheostat for inserting resistance in rotor circuit in starting1 of proper size to insure the starting of motor in not exceeding #ae seconds without overheating4 #cc;a4 ,same as for direct current1 except switch must be either three- or four-pole1 according to current available4 ,,class #d ,,large ,,or ,,small ,,plant ,,where ,,carpet ,,cleaning ,,is ,,of ,,secondary ,,importance4 #a to #ag4 ,same as for ,class #a4 ,omit #ah4 #ah;a4 ,base ,plate1 ,foundation1 etc4 ,provide suitable base plate to rigidly support the exhauster and its motor as a unit1 which shall be large enough to catch all drip of water or oil4 ,provide a raised margin and pads for feet of exhauster frame1 motor1 and anchor bolts1 high enough to prevent any drip from getting into the foundation or on the floor4 #ah;b4 ,provide suitable foundation of brick or concrete1 to which the base plate shall be firmly anchored4 ,the foundation shall be built on top of the cement floor of the basement1 which shall be picked to afford proper bond for the foundation4 #ah;c4 ,construct the foundation of such a height as to bring the working parts of the machine at the most convenient level for operating purposes4 ,exposed parts of the foundation to be faced with best grade white enameled brick4 ,if the base plate does not cover the foundation1 the exposed top surface is to be finished with enameled brick1 using bull-nose brick on all edges and corners4 #ai to #bc4 ,same as for ,class #a4 #bc;a4 ,the guaranteed efficiency of motor shall not be less than #gh at half load and not less than #hd at full load4 #bd to #cb4 ,same as for ,class #a4 #cb;a4 ,motor shall be subject to shop test to determine efficiency1 heating1 insulation1 etc4 ,manufacturers' certified test sheets of motor1 giving all readings taken during shop test1 together with calculated results1 must be submitted to the ,architect for approval before motor is shipped from factory4 #cc4 ,rheostat4 ,furnish and install where shown1 upon a slate panel hereinafter specified1 a starting rheostat of proper size and approved make1 designed for the particular duty it has to perform4 ,it must have an automatic no-voltage and overload release4 ,all resistance for rheostat is to be placed on the back of the tablet4 ,contacts must project through board to front side4 ,all moving parts must be on front of board4 #cc;a4 ,tablet4 ,furnish and place where shown1 a slate tablet not less than in4 thick1 supported by a substantial angle iron frame1 so placed that there will be a space of not less than #d in4 between the wall and back of resistance4 ,mount on this tablet one double-pole1 #bej-volt knife switch1 with two #bej-volt inclosed fuses and one starting rheostat1 as specified hereinbefore4 ,the connections shall be on the back of the tablet4 ,the space between the column and the tablet shall be enclosed with a removable diamond-mesh grill of ,no4 #aj wire in channel frame4 #cd1 #ce and #cf4 ,same as for ,class #a4 #cf;a4 ,automatic ,control4 ,suitable means shall be provided in connection with the rotary exhauster that will maintain the vacuum in the separators within the limit of the machine at point found to be most desirable1 irrespective of the number of sweepers in operation4 #cf;b4 ,controller shall consist of a suitable means provided in the exhauster1 or as an attachment thereto1 which will automatically throw the exhauster out of action by admitting atmospheric pressure to the exhauster only1 but not to the system2 whenever the vacuum in the separator rises above the point considered desirable1 and throw the exhauster into action when the vacuum falls below the established lower limit4 #cf;c4 ,in addition to control1 a positive vacuum breaker having an opening equal to #a in4 diameter pipe net for #f in4 of mercury1 must be provided on separator4 #cf;d4 ,if centrifugal fan is used1 no control or vacuum breaker will be required4 #cg4 ,furnish one separator having a cubic contents of #d4e cu4 ft4 for each sweeper of plant capacity4 #ch to #ef4 ,same as for ,class #a4 #ef;a4 ,tool ,cases4 ,furnish approved hardwood cabinet-finished cases for cleaning tools4 ,each case to be made as light as possible and of convenient form for carrying by hand and provided with a complete set of cleaning tools1 each securely held in its proper place1 and fitted with lock and key1 clamps1 and conveniently arranged handles4 #eg4 ,each case shall contain the following3 ,one carpet renovator in4 by #ae in4 ,one bare floor renovator1 #ae in4 long1 with curved felt-covered face4 ,one wall brush1 with skirted bristles1 #ab in4 long and in4 wide4 ,one hand brush1 with hose connection at end1 #h in4 long and #b in4 wide4 ,one #d-;in4 round brush for relief work4 ,one upholstery renovator4 ,one corner cleaner4 ,one radiator tool4 ,one curved stem about #e ft4 long4 ,one straight extension stem #e ft4 long4 ,at least one hat brush with the system4 #eh to #fh4 ,same as for ,class #a4 #fi4 ,hose ,racks4 ,furnish and properly secure in place1 where directed1 4444 hose racks in basement1 4444 each in first and second stories 74444 racks in all74 ,the racks to be constructed of cast-iron1 galvanized or enamel finish1 and each rack to be suitable for holding #ge ft4 of hose of required size4 #fi;a4 ,hose4 ,there must be furnished with each hose rack #ge ft4 of non-collapsible hose in three #be-;ft4 lengths4 #gj4 ,hose to be #a in4 or #a- in4 inside diameter1 best quality rubber hose1 reinforced in best manner to absolutely prevent collapse at highest vacuum obtainable with the exhauster furnished and to prevent collapse if stepped on4 ,weight of hose to be not over #ab oz4 per linear foot4 #ga to #gc4 ,same as for ,class #a4 #gd4 ,on completion of the plant the pump will be operated with all outlets closed and1 under this condition1 the power consumption must not be more than #ej of that required under test conditions4 #ge4 ,same as for ,class #a4 #gf4 ,to test the capacity of the plant1 4444 hose lines each #ge ft4 long shall be attached to the inlets1 each hose to be fitted with standard vacometer with -in4 opening4 ,under these conditions a vacuum of #a in4 mercury must be maintained in each vacometer4 #gg and #gh4 ,same as for ,class #a4 ,,class #e ,,to ,,give ,,widest ,,competition4 #a4 ,same as for ,class #a4 #b4 ,exhauster to be piston1 rotary or centrifugal fan type4 #c4 ,the piston type of exhauster shall be double-acting and so designed that the cylinder clearance shall be reduced to a minimum1 or suitable devices shall be employed to minimize the effect of large clearances4 #d4 ,the induction and eduction valves may be either poppet1 rotary or semi-rotary1 and shall operate smoothly and noiselessly4 #e4 ,the piston packing shall be of such character as to be practically air tight under working conditions and constructed so that it will be set out with its own elasticity without the use of springs of any sort4 ,if metallic rings are used1 they must fill the grooves in which they are fitted1 both in width and depth1 and must be concentric2 that is1 of the same thickness throughout4 ,the joint in the ring or rings to be lapped in width but not in thickness1 and if more than one ring is used they are to be placed and doweled in such position in their respective grooves so that the joints will be at least one-fourth of the circumference apart4 #f4 ,the piston shall have no chamber or space into which air may leak from either side of the piston4 ,all openings into the body of the piston must be tightly plugged with cast-iron plugs4 #g4 ,the piston-rod stuffing box to be of such size and depth that if soft packing is used it can be kept tight without undue pressure from the gland4 ,if metallic packing is used1 it must be vacuum tight without undue pressure on the rod4 ,proper means shall be provided for the continuous lubrication of the piston rod4 #h4 ,the exhauster of the piston type shall be fitted with an approved cross-head suitably attached to the piston rod2 machines having an extended piston rod for guide purposes will not be acceptable4 ,insert paragraphs #c to #ae from specifications for ,class #a4 #ae;a4 ,reciprocating exhauster shall be provided with the necessary devices for the removal of the heat generated by friction and compression1 that shall prevent the temperature of cylinders or eduction chambers rising more than #ajj ,f4 above the surrounding atmosphere after two hours' continuous operation under full load conditions4 #ae;b4 ,speed4 ,reciprocating exhauster with poppet valves shall operate at an average piston speed not exceeding #bjj ft4 per minute1 with rotary valves not exceeding #cjj ft4 per minute4 ,insert paragraphs #af and #ag from specifications for ,class #a4 ,omit #ah4 #ah;a4 ,base ,plate1 ,foundation1 etc4 ,provide suitable base plate to rigidly support the exhauster and its motor as a unit1 which shall be large enough to catch all drip of water or oil4 ,provide a raised margin and pads for feet of exhauster frame1 motor1 and anchor bolts1 high enough to prevent any drip from getting into the foundation or on the floor4 #ah;b4 ,provide suitable foundation of brick or concrete1 to which the base plate shall be firmly anchored4 ,the foundation shall be built on top of the cement floor of the basement1 which shall be picked to afford proper bond for the foundation4 #ah;c4 ,construct the foundation of such a height as to bring the working parts of the machine at the most convenient level for operating purposes4 ,exposed parts of the foundation to be faced with best grade white enameled brick4 ,if the base plate does not cover the foundation1 the exposed top surface is to be finished with enameled brick using bull-nose brick on all edges and corners4 #ai to #bc4 ,same as for ,class #a4 #bc;a4 ,the guaranteed efficiency of motor shall not be less than #gh at half load and not less than #hd at full load4 #bd to #cb4 ,same as for ,class #a4 #cb;a4 ,motors shall be subject to shop test to determine efficiency1 heating1 insulation1 etc4 ,manufacturers' certified test sheets of motor1 giving all readings taken during shop test1 together with calculated results1 must be submitted to the architect for approval before motor is shipped from factory4 #cc4 ,rheostat4 ,furnish and install where shown1 upon a slate panel hereinafter specified1 a starting rheostat of proper size and approved make1 designed for the particular duty it has to perform4 ,it must have an automatic no-voltage and overload release4 ,all resistance for rheostats is to be placed on the back of the tablet4 ,contacts must project through board to front side4 ,all moving parts must be on front of board4 #cc;a4 ,tablet4 ,furnish and place where shown1 a slate tablet not less than in4 thick1 supported by a substantial angle bar frame1 so placed that there will be a space of not less than #d in4 between the wall and back of resistance4 ,mount on the tablet one double-pole1 #bej-volt knife switch1 with two #bej-volt enclosed fuses and one starting rheostat1 as specified hereinbefore4 ,the connections shall be on the back of the tablet4 ,the space between the column and the tablet shall be enclosed with a removable diamond-mesh grill of ,no4 #aj iron wire in channel frame4 #cd1 #ce and #cf4 ,same as for ,class #a4 #cf;a4 ,automatic ,control4 ,suitable means shall be provided in connection with the reciprocating and rotary exhausters that will maintain the vacuum in the separators within the limit of the machine at point found to be most desirable1 irrespective of the number of sweepers in operation4 #cf;b4 ,controller shall consist of a suitable means provided in the exhauster1 or as an attachment thereto1 which will automatically throw the exhauster out of action by admitting atmospheric pressure to the exhauster only1 but not to the system2 or that shall cause suction from the system to cease whenever the vacuum in the separators rises above the point considered desirable1 and throw the exhauster into action when the vacuum falls below the established lower limit4 #cf;c4 ,vacuum ,breaker4 ,in addition to the controlling devices above specified1 if a reciprocating or rotary exhauster is used1 there shall be placed in the suction pipe to the exhauster an approved positive-acting vacuum breaker having opening equivalent to the area of #a-;in4 diameter pipe and set to open at #ab in4 #cf;d4 ,if centrifugal fan is used1 no control or vacuum breaker will be required4 #cg4 ,dust ,separators4 ,there must be provided at least one separator between the pipe lines and exhauster having a volume of not less than #c cu4 ft4 per sweeper of plant capacity4 ,this separator must be so constructed that no part thereof will receive the direct impact of the dust4 ,if rotary exhauster is used1 this separator must also contain a bag so placed that only the lightest dust will reach same and must be arranged to be readily cleaned without dismantling the separator4 ,if a centrifugal exhauster is used1 this apparatus may or may not contain a bag1 and1 if piston pump is used1 this separator must contain no bags or screens whatever4 ,if a piston type of exhauster is installed1 an additional separator must be placed between the first separator and the exhauster4 ,this must be a wet separator and may be contained in the base of the machine or consist of a separate tank4 ,omit #ch4 #ch;a4 ,same as for ,class #a4 #ch;b4 ,wet separators1 whether separate from or integral with the base of the machine1 must be provided with an attachment which will positively mix the air and water1 thoroughly break up all bubbles1 separate the water from the air1 and prevent any water entering the exhauster cylinder4 #ch;c4 ,suitable means must be provided to automatically equalize the vacuum between wet and dry separators upon the shutting down of the exhauster4 #ch;d4 ,the separators must be provided with suitable openings for access to the interior for inspection and cleaning1 and the interior arrangement of the separators must be such that they may be readily cleaned without dismantling4 #ch;e4 ,all parts of the wet separator tank 7if used7 not constructed of non-corrosive metal must be thoroughly tinned or galvanized both inside and outside4 ,the interior of the wet separator formed in base of exhauster shall be painted with at least two coats of asphalt varnish or other paint suitable to prevent the corrosion of same4 #ch;f4 ,separators must be provided with all necessary valves or other attachments for successful operation1 including a sight glass for the wet separator 7if used71 through which the interior of same may be observed4 #ch;g4 ,the wet separator 7if used7 shall be properly connected to water supply where directed and discharge to sewer where shown on plans4 #ch;h4 ,a running trap with clean-out shall be installed in the waste line4 #ci to #da4 ,same as for ,class #a4 #da;a4 ,waste and water pipe1 in connection with wet separator and jacket1 except waste pipe below basement floor1 to be standard galvanized wrought-iron or steel screw-jointed pipe free from burs4 ,waste pipe below the basement floor is to be best grade1 8extra heavy0 cast-iron pipe1 with lead-calked joints4 #db to #de4 ,same as for ,class #a4 #de;a4 ,fittings on water lines to be standard galvanized beaded fittings4 #de;b4 ,fittings on waste line above basement floor to be galvanized recessed screw-jointed drainage fittings and those below basement floor to be 8extra heavy0 cast-iron with hub joints4 #df to #ej4 ,same as for ,class #a4 #ej;a4 ,if reciprocating exhauster is used1 the exhaust pipe is to be fitted with an approved first-class muffler not less than #ab in4 in diameter and #fj in4 high1 closely riveted and constructed of galvanized iron not less than in4 thick1 and in event an exhauster requiring lubrication is furnished this muffler is to be arranged so that it will also be an efficient oil separator4 ,drip connection is to be arranged at bottom of muffler4 #ea to #ef4 ,same as for ,class #a4 #ef;a4 ,tool ,cases4 ,furnish 444 approved hardwood cabinet-finished cases for cleaning tools4 ,each case to be made as light as possible and of convenient form for carrying by hand and provided with a complete set of cleaning tools1 each securely held in its proper place1 and fitted with lock and key1 clamps1 and conveniently arranged handles4 #eg4 ,each case will contain the following3 ,one carpet renovator1 with slot in4 by not less than #ab or more than #ae in4 long4 ,one bare floor renovator1 #ae in4 long1 with curved felt-covered face4 ,one wall brush1 with skirted bristles1 #ab in4 long and in4 wide4 ,one hand brush1 with hose connection at end1 #h in4 long and #b in4 wide4 ,one #d-;in4 round brush for relief work4 ,one upholstery renovator4 ,one corner cleaner4 ,one radiator tool4 ,one curved stem about #e ft4 long4 ,one straight extension stem #e ft4 long4 ,at least one hat brush with the system4 #eh to #fd4 ,same as for ,class #a4 #fd;a4 ,all brushes to be of substantial construction1 with best quality bristles set in close rows and as thick as possible1 skirted with rubber1 leather1 or chamois skin1 so that all air entering renovator will pass over surface being cleaned4 #fe to #fh4 ,same as for ,class #a4 #fi4 ,hose ,racks4 ,furnish and properly secure in place1 where directed1 4444 hose racks in basement1 4444 each in first and second stories 74444 racks in all74 ,the racks to be constructed of cast-iron1 galvanized or enamel finish1 and each rack to be suitable for holding #ge ft4 of hose of required size4 #fi;a4 ,hose4 ,there must be furnished with each hose rack1 #ge ft4 of non-collapsible hose in three #be-;ft4 lengths4 #gj4 ,hose shall not be less than #a in4 or more than #a- in4 inside diameter1 best quality rubber hose1 reinforced in best manner to absolutely prevent collapse at highest vacuum obtainable with the exhauster furnished and to prevent collapse if stepped on4 ,weight of hose to be not over #ab oz4 per linear foot4 #ga to #gc4 ,same as for ,class #a4 #gd4 ,on completion of the plant1 the pump will be operated with all outlets closed and under this condition the power consumption must not be more than #ej of that required under test conditions4 #ge4 ,to test the capacity of plant1 one hose line #ajj ft4 long shall be attached to inlet farthest from the separator1 with standard vacometer with -in4 opening in end of hose4 ,hose lines shall be attached to other outlets1 each with #ej-;ft4 hose and vacometer in end of hose1 4444 vacometers having -in4 opening and 4444 vacometers having -in4 opening4 ,under these conditions #d in4 mercury must be maintained in vacometer at end of #ajj ft4 of hose4 #ge;a4 ,test of ,separators4 ,at each of ---- points1 near ---- outlets on different risers selected by the 4444 representative1 the contractor shall furnish and spread on the floor1 evenly covering an area of approximately #ej sq4 ft4 for each outlet1 a mixture of #f lbs4 of dry sharp sand that will pass a #ej-mesh screen1 #c lbs4 of fine wheat flour1 and #a lb4 of finely pulverized charcoal1 if wet separator be used1 and #f lbs4 of ,portland cement1 if bag be used4 #ge;b4 ,fifty feet of hose of size required by the system used shall be attached to each of the ---- outlets1 and the surface or surfaces prepared for cleaning shall be cleaned simultaneously by operators provided by the contractor until all of the sand1 flour and charcoal has been taken up1 when the exhauster shall be stopped and the dirt removed from the dry separator and spread on the floor again1 and the operation of cleaning repeated until the mixture has been handled by the apparatus four times4 ,if1 after thoroughly flushing the system at completion of the above run1 any dust or mud is found in the cylinder1 ports1 or valve chambers of the displacement exhauster1 or if less than #ie of the dirt removed is found in the dry separator of the centrifugal exhauster1 it shall be deemed sufficient ground for the rejection of the separators4 ,if bag is used1 same must not be disturbed until after capacity test1 which will be made with material in separator after being picked up the fourth time4 #gf-gg4 ,same as for ,class #a4 #gh4 ,evaluation of proposal 7for #d-sweeper plant73 ,no proposal will be considered which contemplates furnishing an exhauster requiring more power to operate under test conditions than3 ,full load1 #ad ,k4 ,w42 three-quarter load1 #ab4be ,k4 ,w42 one-half load1 #aj4e ,k4 ,w4 ,test ,requirement3 ,paragraph #ge to be considered full load4 ,to reduce the load to three-quarters1 one -in4 vacometer opening to be closed2 to produce one-half load1 one -in4 opening to be closed in addition to the -in4 opening4 ,bidders are requested to state in proposal the power consumption required by their apparatus at full1 three-quarters and one-half loads1 and in case the guarantees of the various bidders differ1 they will be evaluated as follows for the purpose of comparison3 ,for each full ,k4 ,w4 of power consumption or fractional part thereof there will be allowed the following amount or proportionate parts for fractional parts of a ,k4 ,w4 hour at the various loads3 ,per ,cent4 of ,full ,load #ajj #ge #ej ,amount #aef4jj #fb4jj #id4jj ,as an illustration1 let it be assumed that proposals have been received offering equipment in accordance with specification requirements1 and the one offering the most economical apparatus based on guaranteed power consumption names the highest price for the installation4 ,to determine if the purchaser will be justified in accepting the highest proposal1 let it be assumed that he has guaranteed a power consumption of #a ,k4 ,w4 less at full load1 #j4ge ,k4 ,w4 less at three-quarters load1 and #j4be ,k4 ,w4 more at half-load than the lowest bidder4 ,under these conditions the algebraic sum of the saving of the higher bidder over the lower bidder would be #aef #df4ej - #bc4ej #agi1 which is the additional amount in dollars which the purchaser would be warranted in paying for the apparatus of higher efficiency4 ,in making the economy test to determine if the guaranteed power consumption has been fulfilled1 an integrating watt meter1 previously calibrated and found correct1 will be placed in circuit and a two-hour run made at each load and the power consumption based on the meter readings4 ,penalty4--,it must be distinctly understood to be one of the conditions under which bids are to be submitted for the work embraced in this specification that the apparatus shall meet every requirement of the specification and the guaranty for efficiency under which conditions the contract price will be paid4 ,in the event the apparatus tested fails to meet the specified requirements for capacity or economy1 or both1 the ,architect shall have the right to reject the apparatus1 absolutely1 and require the installation of satisfactory apparatus1 which shall comply with the contract requirements2 or if he elects to accept the same1 in the event the capacity or efficiency at any load 7irrespective of other loads7 is less than that named in the proposal1 then the contract price shall be the amount named in the contract for a satisfactory plant1 less the amount of deficiencies shown by the test based on the following3 ,for ,capacity4--#ejj4jj for each inch of vacuum and a proportionate part thereof for each fraction of an inch below the #d in4 required in vacometer when operating under full load4 ,for ,economy4--,deduction for each ,k4 ,w4 or a proportionate part thereof for each fraction thereof required in excess of guarantee4 ,percentage of ,full ,load #ajj #ge #ej ,penalty #bbi4jj #ic4jj #ada4jj 99 99 99 99 99 ,this evaluation was based on the same time of operation and cost of current as that used in illustration under tests 7,chapter ,,xii74 ,the maximum power to be allowed for plants of various capacities should be as follows3 ,capacity in #ajj #ge #ej ,sweepers of ,load of ,load of ,load #h #bd #bj #ag #f #bj #ah #ae #d #ad #ab4be #aj4e #b #g4e 44444 #f4be ,in event that the plant is to be run with vacuum 8on tap10 as in a hotel1 a guaranteed power consumption at no load should be required and evaluated on the number of hours the plant will probably operate under these conditions4 ,this will be the largest item in the evaluation under such conditions4 ,,chapter ,,xv4 ,,portable ,,vacuum ,,cleaners4 ,while this book is primarily intended to deal only with vacuum cleaning systems1 which would limit the work to such apparatus as is permanently installed within the building to be cleaned1 the author considers that it would not be complete without some mention of the portable cleaners which are so popular at the present time4 ,on first consideration1 the portable cleaner would appear to have a considerable advantage over the stationary type in that the length of hose is usually limited to not over #ae ft4 and there is no pipe line1 which results in the elimination of practically all friction loss1 giving practically the same vacuum at the renovator as at the exhauster4 ,this should result in a saving of practically #ej of the power required to operate the exhauster4 ,referring to ,chapter ,,xii1 we find that the power required to operate a really efficient vacuum cleaning system is approximately #b4e ,h4 ,p4 per sweeper4 ,if a portable cleaner1 with the same efficiency and capacity1 be built1 it would require at least #a ,h4 ,p4 ,such a cleaner would not be portable in the sense of the term as applied to the most popular cleaners today4 ,the same type has been built on special order by the ,american ,radiator ,company1 which mounted its #a ,h4 ,p4 ,arco ,wand machine on a truck4 ,this cleaner weighs several hundred pounds and could be moved up and down stairs about as easily as a sewing machine and would not be of any service in a building not equipped with elevators4 ,the power required to operate this cleaner is also so great that special power wiring and large capacity outlet plugs have to be installed throughout the building4 ,such equipment has been provided in at least two department stores where these cleaners are in use4 ,this means that one wires his building for vacuum cleaning instead of piping it1 and there is also the necessity of moving a heavy machine about to do the same work as a stationary plant4 ,it would appear to the author that the cost of wiring would about equal that of piping and that the additional labor required to move the machine about would cost as much as the additional power needed by the stationary exhauster4 ,this cleaner1 as well as all other portable cleaners1 discharges the air from the exhauster directly back into the apartment cleaned1 and is open to the same objection that was raised against the early compressed air cleaners4 ,while all the dust may be caught by the dust bag1 the microbes are allowed to escape with the air and the cleaner is not a sanitary device by any manner of means4 ,there are a few portable machines using rotary exhausters of the ,root type1 and piston pumps1 all of which are heavy to move about and1 in making them as light as possible1 the efficiency of the exhauster has been sacrificed4 ,these machines will do the same quality of cleaning as the stationary plants recommended for residence work and they require about ,h4 ,p41 which is no less than is needed for a stationary plant of the same capacity and efficiency4 ,the most popular type of portable cleaner is one which can be attached to a socket or plug connected with the lighting system4 ,this should limit the power consumption to ,h4 ,p4 ,however1 many of these cleaners use as much as #djj watts and a fair average for cleaners retailing at about #abe4jj is #bej watts4 ,such cleaners will exhaust about #be cu4 ft4 of air with a vacuum of #a in4 mercury at the vacometer1 a -in4 orifice being used4 ,the theoretical power required to move the air is approximately #ej watts and the overall efficiency of these cleaners is1 therefore1 about #bj1 as against #dj to #ej in a good1 one-sweeper stationary plant4 ,the power expended in operating these portable cleaners in proportion to the work done is no less than with an efficient stationary plant4 ,portable cleaners have been made in many types but practically all the standard makes use one or two forms of vacuum producers1 either the diaphragm pump or the single or multi-stage fan4 ,the pumps of the former type are able to produce a vacuum as high as #f in4 to #aj in4 of mercury1 when no air is passing1 and will displace as high as #cj cu4 ft4 of free air per minute1 when operated with a free inlet4 ,they produce about #a in4 of mercury at the carpet renovator when operated on an ordinary carpet4 ,when small-sized upholstery renovators are used1 a much higher vacuum is possible4 ,when operated with bare floor renovators or brushes1 the quantity of air exhausted is not much over #bj cu4 ft4 per minute and they make very inefficient bare floor and wall cleaners1 but will do thorough carpet and upholstery cleaning provided a small enough renovator is used4 ,machines using a multi-stage fan will produce a maximum vacuum of approximately #b in4 of mercury when exhausting no air1 and will produce a vacuum of approximately #a in4 of mercury when operated on an ordinary carpet4 ,with an unrestricted inlet1 they will exhaust from #dj to #ej cu4 ft4 of air per minute4 ,when operated on a bare floor1 they will exhaust approximately #cj cu4 ft4 of free air per minute4 ,they are1 therefore1 more efficient floor cleaners than the pumps1 but cannot do thorough carpet and upholstery cleaning1 no matter how small the renovator4 ,the smaller-fan type of machines1 in which the fan is placed integral with the carpet renovator and in which hose is not used in cleaning floors or carpets1 are provided with a single-stage fan4 ,they produce a suction of not exceeding in4 of mercury when no air is exhausted and will exhaust from #e to #aj cu4 ft4 of free air per minute when operated on a carpet4 ,with a free inlet they will exhaust from #ae to #bj cu4 ft4 of free air per minute4 ,these machines are little if any better than ordinary carpet sweepers4 ,machines of this type are open to another objection in that the dust bag is placed on the outlet of the fan and the dust in the bag is continually agitated by the passage of the air1 with the result that all the finer particles of the dust are blown through the bag back into the apartment4 ,to be effective1 the dust bag must always be placed on the suction side of the exhauster and should be so arranged that the dust will not quickly cover the entire area of the bag1 for1 when this occurs1 the suction is quickly reduced to such an extent that no further cleaning can be done until the bag has been cleaned4 ,there is another type of mechanical cleaner manufactured by the ,hoover ,suction ,sweeper ,company which is provided with a mechanically-operated brush for loosening the dirt from the carpet4 ,the dust is then conveyed through a single-stage fan to a dust bag4 ,the cleaner does not depend on the vacuum to loosen the dirt and will do quite effective carpet cleaning with a small expenditure of power4 ,owing to the small suction produced1 it is of little value for cleaning anything but carpets4 ,from the experience the author has had with portable vacuum cleaners1 some thirty makes having been tested for the ,treasury ,department by him and by the ,bureau of ,standards1 the use of such cleaners is not considered as either an efficient or sanitary means of mechanical cleaning4 ,if a cleaner requiring small power is required1 one of the smaller stationary plants1 costing not over #cjj4jj and operating with or ,h4 ,p41 is considered a better investment than #abe4jj paid for a portable cleaner4 ,if the purchaser feels that he cannot afford to pay more than #abe4jj for his vacuum cleaner1 a type such as the ,water ,witch can be furnished for this price4 ,this cleaner is placed in the basement1 with arrangements for starting same from any floor4 ,the manufacturers state that this apparatus produces a vacuum of #b in4 mercury in a carpet renovator1 #d in4 mercury in an upholstery renovator and exhausts #be to #cj cu4 ft4 of free air per minute with open hose4 ,the machine operates by water pressure and the manufacturers state that it requires about #f to #h gals4 of water per minute4 ,all air is exhausted outside of the building and all dust washed down the sewer with the exhaust water4 ,it is therefore1 a fairly efficient and sanitary cleaning system4 ,the statements made above apply to parties who own their residences and occupy offices in modern buildings4 ,there are1 besides these1 a great many who live in rented houses and apartments or occupy offices in buildings where the owners are not sufficiently progressive to install stationary cleaning plants4 ,to supply the needs of this class is evidently the field of the portable cleaner1 as even the poorest of these machines is more effective in the removal of dust and dirt than the broom and carpet sweeper4 ,the selection of a portable cleaner by one who must necessarily resort to the use of such a cleaner should be made with care4 ,the motor should be looked into and only one which has brushes readily removable and one in which the condition of the brushes can be easily noted should be selected4 ,lubrication is important4 ,a good cleaner should be so constructed that it can be operated for at least #ajj hours without relubrication4 ,the dust bag should always be on the suction side of the vacuum producer and of such a design and construction that at least peck of a mixture of #dj sand1 #cj flour1 #ae sweepings and #ae ,portland cement can be picked up from the floor and retained in the bag and the machine still be capable of picking up material from a bare floor4 ,a good test for capacity of a portable machine is to pick up peck of such material1 then fit a thin disk with -in4 diameter opening over the end of the hose4 ,a machine1 to be of any value1 should show a suction of #c in4 water and a first-class machine will show #h in4 under these conditions4 ,this will do fairly good bare floor work4 ,to ascertain if the machine will clean carpets1 use a similar disk with -in4 diameter opening1 when a suction of #g in4 water indicates the lowest value and #af in4 about the best that can be obtained from any portable cleaner4 ,cleaners must be readily portable and should not weigh exceeding #ge lbs4 ,transcriber's ,notes ,inconsistent and unusual spelling have been retained4 ,in several places the text appears to be incomplete or jumbled2 this has not been corrected4 ,in many of the illustrations reference letters are given in uppercase whereas the text uses lowercase letters2 this has not been standardised4 ,inconsistencies and differences in wording and structure between the ,table of ,contents and the text have not been rectified4 ,page #hc1 paragraph starting ,much of the hose in use today 4443 as printed in the source document2 part of the text may be missing or mixed up4 ,changes made3 ,illustrations and tables have been moved outside text paragraphs4 ,in some illustrations reference letters have been enhanced for the sake of clarity2 in ,fig4 #fa reference #a has been added4 ,obvious minor typographical and punctuation errors have been corrected silently4 ,in multiplications1 the letter x and the multiplication symbol 77 have been standardised to the latter4 ,page #ch1 ,table #b3 ,f changed to ,f cf4 text4 ,page #ada3 ,o changed to ,o cf4 ,fig4 #gg;a4 ,page #adi3 444 by using metal shins 444 changed to 444 by using metal shims 4444 ,page #agj3 444 the control 7,fig4 #ajg7 444 changed to 444 the control 7,fig4 #ig7 4444 ,page #bje1 item #cc3 444 approved made 444 changed to 444 approved make 4444