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FILE NAME Owens Corning OC DATE 1937 DOC OC432 DOCUMENT DESCRIPTION Gov Report - A Study of Dust Control Methods in an Asbestos Fabricating Plant ten ied PLAINTIFFS EXHIBIT NO 0-02 CASE NO BML / 87- IDENTIFICATION ADMITTED toupe puiltapepupiltapte khon kg^i kookt kookt -t . 2 : T. 7 s ait 23 eR 2 . ore. 3 : ett ~ ss . hy 7 soa toe Pe .2 e of, ee oh, | Se < Ree e Pas s 4 a.o. t = ae bt - ot Seno$. Pe hes | ate ase of in \ ro ae Le ae f. 6 oct ag ote wok A oft U. S. TREASURY DEPARTMENT HENRY MORGENTHAU Ja Secretary PUBLIC HEALTH SERVICE THOMAS PARRAN Surgeon General A STUDY OF DUST CONTROL METHODS IN AN ASBESTOS FABRICATING PLANT BY RICHARD T. PAGE Assistant Public Health Engineer AND J. J. BLOOMFIELD Passed Assistant Sanitary Engineer United States Public Health Service REPRINT No. 1883 FROM PUBLIC HEALTH REPORTS VOL 62 No. 48 November 26 1937 Pages 1718-1727 | CORNING FIBERGLAS CORP LEGAL & PATENT DEPT REC'D SEP 15 1941 UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON: 1988 For sale by the Superintendent of Documents Washington C. One . Price 10 centa -_- stgen Dez va 5 t sy OK oe 20 me, Seng te BU Fuad he FES my A ro te ws 1 %, wo ee xe < Toe . Sr wwe * * vos fy Seo geee MS. Beyer Pais eee . He Regaore =< 4. ' 2B pp BixCsdiceas ray wan SS ~ See set Se: ats: Haaten Rass yore pre aney 3 Sea po oN ene : DUST CONTROL IN AN ASBESTOB PLANT 3 These factors must be considered when comparing dust processes concentrations reported in this plant with the data which have been reported for other plants were employed in this plant of whom Approximately 300 persons asbestos dust hazard 180 worked in departments having a potential namely preparation This study was confined to these departments and winding and weaving The occupa- carding spinning twisting is shown in table 1 tional distribution of exposed workers and dust exposures of workers in an asbestos textile plant TABLE Occupations varage dost concentration M. P. C. F. Ocupation Occupation Ocupation Number of workere NormalNormal Without baust venvetntii lation Preparation Pickermen Pickermen Pickermen Pickermenbuilders PickeOrthmeersn Carders Stock rollers Card tenders Wick rope and cord Spinning twisting SpiningSpinning Male spincers and windingwinding and helpers 8 spinner Cop winders Twisters Univernal winders Yeaving Others Yeaving Yeaving Weavers cloth Wet cloth Tape and listing Oreelers Inspectors Inspectors Tape Other * 0 *** *** *** ** a o gho = o gho o gho o gho o gho oowe y 18 \ woeees 4224 4224 4224 4224 mer rae 167 60.6 119 148 1.7 1.7 i 1824 60 |. emernemnne [scence wees pee 5 errr 129 ae 11.0 1. 10 9.6 9.6 je ut a7 00.6 1818 see 8 11. 21 oe LB | system 1 Dust nabaust Bample after 1 for this operation hour's operation without exhaust loading #Sample #Sample taken inside blo during METHOD OF STUDY included a study of atmospheric dust concentra- This investigation study of the exhaust systems tions in the factory workrooms and or used to removeatamsobsepshteosridcudsutst samples were collected at the workers sampling apparatus 5 Eighty breathing level with the impinger dust conditions and 13 Sixty of these represented present working been turned off conditions while exhaust apparatus had represented A collecting medium containing 25 percent ethyl alcohol for 1 hour flocculation without causing ienxcdeissstiivleledevwaaptoerratwiaos n finouenidthteor ptrheevesnatmpling flasks the counting . ee oy wmewt cae re ag ar ... ... se Amite & drone. voty Diam Seg we we eer ewp ink 2 ches Teo Cer ey. nth w. ists hid .. od . hab Bit os iat ofthe 7.Met a 4 hesoats ! . . aah es ae ey ee THYMote ^' eo 4 a? * , qsint ve * i heAreyty epee. _s dhe y md bd technique described by eyepiece having an engraved square equivalent to fourth the standard Whipple square was used in to count only one counting Since it is customary quadrant of the Whipple field the same volume of sample 0.25 cubic millimeter per field was counted 7 The quantities of air removed through the various . exhaust were calculated from pitot systems Entrance velocities at description of exhaust systems velometer and open hoods were measured with an Alnor checked with a vane anemometer anemometer Most of the boods were of the enclosed type designed to exhaust only vent the escape of asbestos dust into the workroom Where measurements were impractical air volumes individual hood were calculated from exhausted through each Whenever differences in measurements of main velocities hoods on the exhaust exhaust volumes were noted between similar same operation the average value is given DESCRIPTION OF PROCESSES AND DUST CONTROL MEASURES Unloading Asbestos is received in burlap bags containing 100 pounds of Cotton is received in standard bales These are the fiber used in the preparation of asbestos .. yarn at this polnalnytraw materials storage and transportation of the packed raw materials hazardous occupations were not The progress of the material from to completed fabric is shown by means of a flow sheet raw fiber vidual processes and the fig Indi- measures for dust control are described below PREPARATION DEPARTMENT DEPARTMENT Crushing of the asbestos fiber arrives at the crushed fiber but most of the crude fiber has plant as pre- other than mining sorting screening screening and dumped from the bags into wheel received no treatment This latter type is hand 15 minutes These crushers have crushers and crushed from 5 to two heavy heavy rollers attached to a radial axle and revolve on a surfaced traytray in which the is placed During the crushing the asbestos fiber is asbestos stirred by revolving scrapers After being crushed constantly the replaced in the bags and carried to the asbestos fiber is were not enclosed or exhausted in any way but opener the Crushers tion in the preparation department was sufficient general ventila- concentrations of dust near this operation to prevent high Crusher men had res- ... * > - * Meete totalled dw . Rate 1 > eo tnd be 4, naa" DUST CONTROL IN AN ASBESTOS PLANT RAW MATERIALS COTTON CRUDE ASBESTOS MILL ASBESTOS RECOVERED MATERIALS ROVING WASTE CYCLONE & SETTLING CHAMBER WASTE BAG HOUSE WASTE CRUSHERS 4 COTTON OPENERS q ASBESTOS OPENERS & VIBRATING SCREENS ROVING REOPENER y VIBRATING SCREEN WILLOWER SSCREECN REENWILOWER | PICKERS MARKET 4 WICKING TWISTED CORD MACHINES | ROPE TWISTING MACHINES STOCK BINS CARDING DEPT . CARDS 2 ROVING CARDS . MULE SPINNERS RING SPINNERS 4 FOSTER WINDERS SPOOLERS) CHEM TREATMENT & BRAIDING DEPT NOTE HAVE DUST EXHAUST UNDERLINED UNDERLINED PROCESSES PROCESSES Process flow sheet asbestos textile plant Flats SYSTEMS while loading or unloading the operators and usually wore them of of a crusher man tending trees crushers The average exposure crushers was 3.5 M. P. P. C. F. and Janitors were provided with respira- - in the preparation department and all repai^rme^ncg oncentofrfainetmiillioon ns . |. * All employees tors of a type approved by the U. S. Bur of Me inesaAgnu inni 4 ( : b t - ae . 3 we: . "3 oi 3 f..- af a . % Be oF ew co 2%-: a? an Lhe Zim eee ase _- : Arba sits tt pwbetl 5 senate a . 6 CONTROL CONTROL AN ASBESTOS ASBESTOS PLANT screening crushed tro=n from Asbestos opening screening Asbestos Asbestos opening opening screening asbestos asbestos fiber dumped dumped : bags floor beside wooden openers and lifted into hand the food feed4 . lattice hopper with operation design were operation same was schematic fig 2. The feed lattice hopper second partially enclosed exhausted exhausted the top lattice _ partially exhausted bottom bottom from the 4) second hood opener opener hood The opened and settled dust from by the bottom of and pneumatically transported opened was picked where up by the large portion the dust dust onto an enclosed enclosed asbestos opener fine fibers entering entering asbestos opener opener CONVEYOR 3 CONVEYOR =. s A and B. of unopened Miovax hoods Clumps Clumps unopened unopened pieces pieces too heavy to be lifted fell onto onto enclosed enclosed belt conveyor conveyor the pneumatic openers and were serving fell carried conveyor both shown fig to recovery process Exhaust Exhaust volumes process conveyor conveyor follows Hood 400 volumes through hoods pneumatic conveyor conveyor conveyor A hood 400 hood pneumatic 1,800 cfm cfm ) 400 conveyor conveyor velocity velocity 2,730 feet minute pneumatic conveyor conveyor 1,800 A minute Each opener had own cyclone cyclone enclosed and ex- hausted vibrating vibrating screen beside charging charginsgcreenhopOperndreawin4 g 40 000 cfmano d n oveer the dis beside the charging hopper drawing 400 cfm and hoods, one one Over the dis. eR teite acee ra! eet Sg Se ae. Sith TS Be gn.Spee eset * ,; we tai ine Sask mn RETO tarmac sind eee 5 pd ee 1 Mase a le LE te Tre ex zh,i Ta sot ae Nt, ee Teens msa. Seereet A Be ty er tern, 4 ae Nsfg SS ee vibrating and Figure Fiber recovery process Willower . oe '= bas os o 3 sober at ea evoen rte Se~ ee eat @ per aN AFM SETS TATE . Oey ~fl TO ow? pepe oy pat feet +1 ce ct . 3 te * fi Public Health Reports Reprint Na 188 faces lap ers, ogre } AN ont a et hs) IT PRETO PLATEPLATEPLATE Rae 4 SE . re. - Flava Breaker and moving cards wore HO ene o*% tes rod Hae et pig ubed EIAs gabh: i ete eet bl) SEN cy DUST CONTROL IN AN ASBESTOS PLANT 7 end of the screen and the stock car drawing 770 cfm The charge drawing 615 second screen had one bood only over the discharge and cfm Short fibers and rock particles passing the screens fell through a chute to the enclosed recovery conveyor Fiber failing to pass these screens dropped into a stock car Full stock cars were pushed to a platform scale and then to the mixing beds The same men charged the openers and filled the stock cars The average dust exposure of asbestos operators was 3.6 M.P.P.C.F. M.P.P.C.F. Cotton openers best grades of insulation contain very small amounts of cotton if any but in all other cases cotton fiber is mixed with asbestos fiber to improve its spinning qualities At this plant the batch seldom contained more than 15 percent of cotton by weight but as much as 20 percent cotton was used in lower grade yarns The stage Lowell cotton opener was provided with exhausts at three points 770 cfm of air were exhausted through a canopy bood over the ecdlattice 270 cfm from the bottom of the primary opener and 1,120 cfm from the bottom of the secondary opener Opened cotton fiber was discharged into stock cars No samples were taken at the was about 2.4 cotton openers but the operators average exposure M. general air preparation department Weighed quantities of asbestos and cotton were placed in alternate layers in the mixing beds Occasionally layers of roving waste from the carding room were reopened and added to the bed Mixing was done in six exhausted booths each 10 feet 2 inches deep by 6 feet 10 inches wide by 6 feet high Sides of the booths were while the back consisted of a removable wood and canvas pseecrtmiaonn enEtach booth was covered by a pyramid hood 32 inches high through which approximately 1,025 cubic feet of air per minute hood were exhausted The velocity of air motion into these booths paevreraged 50 feet per minute during bed making and about 30 feet per minute during picker loading Dust concentration averaged 5.4 M. for the making operation After a bed had been placed the picker operator removed the rear partition of the booth and forked the batch into the charging hopper of a picker fig 3 The picker machine mixes the fibers in revolving beaters The four machines represented three different operations and two different types of exhaust systems The first machine not in operation during this study discharged mixed fiber into a stock car This material was then passed through a second picker for remixing The second and third machines discharged mixed fiber onto a belt Conveyor which transported it to bins in the carding room The product of the fourth picker was carried to the carding room by a pneumatic conveyor Each of the first three machines had a hood over the charging lattice exhausting approximately 500 cfm a pipe exhausting about 1,650 cfm from the bottom settling chambers = ee ee ete levls dust in ae Hn ame eee we ate ~ OH ements itl Bee laAd O eae l fen et ? ns 8 DUST CONTROL IN AN ASBESTOS PLANT under the main picker drum and a hood over the end of the discharge lattice exhausting about 400 cfm The fourth picker had the same hood arrangement over the charging lattice but had no bottom exhaust and the mixed fiber was removed by pneumatic conveyor exhausting approximately 2,000 cfm of air at a velocity of 2,550 feet per minute The picker operators wear respirators during the charging operation Dust concentrations during picker charging varied from 4.0 to 9.5 M. P. C. averaging about 6.7 M. P. C. F. Recovery processes Waste roving from the card room was returned to the preparation department for reopening The roving reopener was exhausted only from the pit below the last beater but the 1,780 cfm of air drawn through this hood was sufficient to prevent the escape of dust through the discharge lattice The dusty air collected by the exhaust systems in the preparation and large carding department was blown into a settling chamber occupying two stories in the end of a separate building Air was displaced from this room to a bag house occupying the second floor on the other end of this building Dust was filtered out by burlap filters stretched on frames The filters were beaten down by hand daily during the noon rest period The collected dust was removed during the weekend down and stored in bins in the preparation department house dust was screened on a completely enclosed and exhausted vibrating screen background fig 4 and the long fibers were removed to a cyclone collector by a pneumatic conveyor The dust from the settling chamber the long fibers from the house dust and fibers separated by cyclones on the exhaust lines from the spooling operation and the weaving department were passed through a willower and vibrating screen fig 4 Approximately 250 cfm of air were exhausted from the top of the charging lattice and 620 cfm from the discharge side of the opening drum Dirt passing the screen dropped onto an inclined tray and was removed by an exhaust hood drawing 730 cfm Fibers which did not fall through the screen were removed by the hood at the lower end of the screen 1,710 cfm and pneumatically conveyed to a cyclone collector Rock and other impurities not picked up by the pneumatic conveyor fell into a waste box below the end of the screen The market for recovered fiber is limited and such fiber is usually the of too soiled for use in grade textiles Consequently only part of collected dust was passed through this process Average exposure operators was estimated at between 3 and 5 M. P. C. F. As a measure of the effectiveness of the dust control system in the preparation department the exhaust fans were shut off for one hour Pneumatic conveyors remained in operation Dust concentrations increased steadily to about One 50 M. P. P. C. F. at which time the exhaust fans were turned on oH The samples taken during this period of time showed an increase Pe ' FO eEE OM WRB AR 1eRAG set ees en ek TOT as Bet:os Wcate MWEas Cy , nEsA : 2: 2s ro . id. h ; ay t}a$ & i peYs AY t Phy \ omvft agedSet a ets ae DUST CONTROL IN AN ASBESTOS PLANT 9 were only a partial measure of uncontrolled conditions since the hoods ~ and enclosures had a definite control value While the location and design of hoods were the most important factors in dust control in the preparation department general ventila- tion helped prevent high dust concentrations This department occupied approximately 320,000 cubic feet of space from which ap- proximately 34,650 cfm of air were exhausted Consequently 6.5 air changes per hour were produced by mechanical ventilation which was supplemented by natural ventilation through doors windows and roof ventilators Fortunately heating was not a problem in this plant CARDING DEPARTMENT Mixed fiber from the preparation department was dropped from pneumatic or mechanical conveyors into bins in the carding depart- ment The total volume of exhaust from four bins was 6,850 cfm the major portion of this air being drawn through the one or two bin doors left open during the loading of carding room stock cars Dust concentrations as high as 40.4 M. P. P. C. F. were measured inside an active bin while the dust concentration just outside the door of the same bin was only 4.6 M. P. P. C. F. Workers classed as stock rollers fork the mixed fiber from the bin into stock cars This operation is supposed to be performed with both stock car and stock roller outside the bin door This rule of keeping out of the bins should be strictly enforced However stock rollers wearing respirators like to push their cars under the chute and then climb into the car and tread the stock The cards are machines having a series of revolving cylinders wound diagonally with strips of leather set with fine sharp steel bristies Carding removes remaining small bits of rock and combs the fibers into a more or less parallel condition to facilitate spinning At the time of this study 31 roving card units and 2 wicking cards were being operated A roving card unit fig 5 consisted of two cards a breaker or primary card and a finisher or roving card The mixed fiber was fed by hand from the stock car to the feed hopper of the breaker card The stock roller wore a respirator during this operation The fiber passed through the breaker card emerging as a loose blanket or web It was carried to the finishing card by a lattice conveyor or camel back The fiber was stripped from the last cylinder of the finisher onto a moving leather apron where a set of reciprocating rubbers condensed it into loose rovings of unspun yarn These rovings are wound on long jack spools to be taken to the spinning department The rovings at the extreme ends of the cards cannot be used for spinning because they lack uniform thickness These rovings are collected by two small boods and pneumatically conveyed to a collection bin for return to the preparation department om oe ro on . ae a . 10 DUST CONTROL IN AN ASBESTOS PLANT The exhaust system applied to roving cards is shown schematically in figure 7. The quantity of air exhausted varied from 1,100 cfm to 1,800 cfm on different carding units with an average exhaust of 1,440 cfm per unit Cards are partially enclosed and only sufficient air is exhausted to prevent the escape of dust Each breaker card is exhausted at three points Hood B exhausts from the top of the feed hopper over the feed apron This hopper was enclosed and covered the cover being lifted during filling About 160 cfm of air were exhausted through the hood Hood A exhausted the top fly from the enclosure covering the main carding cylinder Hood CAMEL CONVEYOR CIMT CAMEL 1 | IOe OF | =~ A BREAKER { Wl FINSHER | ! wage 1G . C FEED BOX COVER Figure Schematic plat of card exhaust system C exhausted the bottom fly from the settling chamber under the carding cylinders Approximately 285 cfm were exhausted of through each of these hoods The finishing card had four exhaust connections besides the two small hoods G which removed the waste roving Hoods E and F correspond to hoods A and C respectively on the breaker approximately 255 cfm each The card providing an exhaust doffer card cylinder doffer combs and roving apron were exhausted from below through hoods D and Dat 70 cfm each About 40 cfm were exhausted through each roving collector ee 5 Hite Sie aan 7 IEEE ve ew aaa) and oan) daniel te ttien tesd Se - a teat ay topes phos Petey gna te . ott 7 4 . ; Cent ee rs s tows s f., oe Sme etaomnrie got bag onto Anpbilies bc B achive vebid.cals debs steno Ee aeOR i . hat | he eet aie ee TOOL PeUure eye PN e e DUST CONTROL IN AN ASBESTOS PLANT 11 The volumes of air exhausted through each bood were estimated on the basis of pipe areas Actual volumes showed wide variations on different units Single cards were used in the manufacture of asbestos wick and- rope since a thick roving was desired The wick or rope was twisted from the unspun roving The wicking cards were exhausted at three points Approximately 380 cfr of air were drawn from under the feed lattice 490 cfm were exhausted from the top of the main cylinder cover to remove the top fly and 550 cfm were exhausted from the bottom- By settling chamber concentrations during carding averaged 1.7 M. P. P. C. F. This was also the average exposure of wicking card operators and wick and rope twisters Samples taken near the carding department weight scales showed less than 0.5 M. P. P. C. F. Card rolls were cleaned and ground at night except in cases of emergency Cleaning was done with hand scrapers made of strips of card cloth and the card cylinder was turned by hand Grinding was done with the usual type of card grinders The large roll was ground in place in the carding machine Slightly greater quantities of air were exhausted during grinding due to the decreased loss of head resulting from removal of the wooden card covers The small card cylinders were ground in a grinding frame These frames were partially enclosed and covered with a canopy bood exhausting 2,330 cfm per grinder Dust concentrations averaged 0.65 M. P. C. F. during grinding A special run of a group of carding machines made with all exhaust ventilation turned off and windows closed showed that dust concen- trations steadily increased At the end of 1 hour the concentration was 62.4 P. the air Under Dormal operating conditions about 64,000 cfm of air are exhausted from the carding department This is equivalent to about 5.5 air changes per hour disregarding natural ventilation through windows on all four sides of the room winding The Spinning twisting and yarn as roving is twisted or spun into compact threads on either mule or ring spinning frames In this plant most of the spinning was done on mule spinners The spun thread was transferred from the spinning spindles to spools on Foster winding machines spoolers Spooled thread to be used as filler or woof in woven cloth was rewound on a cop winder into cops which will fit into the loom shuttles The remaining spooled thread was respooled on twisters which twist several threads into a yarn The number of strands used determined the size of yarn Both plain and metallic yarns were twisted Metallic yarn contains one or more strands of fine wire Part of the twisted yarn was used in cloth weaving while the remaining yarn was rewound on Universal winding frames for the market tore. + en mw te ee . Pp - At al od eh s - . ade - . . . own sae wt _ . % Ee wee eae : wo Was, aan a - wT ier a aS Vandy done a mary eT ~ me Marat It =. DUST CONTROL IN AN ASBESTOS PLANT 12 recorded Mule spinning was separated from other operations in this depart- Natural ventilation was good and no ment by partial pwaerrteitiuosnesd The average dust concentration was exhaust systems with maximum of 1.3 M. P. C. F. 0.85 M. P. P. C. a machines were Ring spinning cop winding and Universal winding ex- with the twisting machines Average located in the same room which were not themselves posures in the first three opduesrtatfiroonms the twisting operation With especially dusty were due to one twister the remaining the exception of a trial exhaust system on with exhaust The trial system was machines were not provided and is to be installed on all twisting reported to be satisfactory of exhaust system applied to Foster winders Notas Bebematic views a the bottom of the twisting frame was machines In this system cfm of air per machine was drawn down- enclosed and total of 1,700 five conical hoods distributed ward past the twisting yarns and through winding along a central exhaust duct operations various operations in this room Average dust concentrations at the M. were ring spinning 5.0 MM..C P. P. . C. F copand twist6i.n9g 11.0 M. P. P. Universal winding 2.8 M. P. P. C. F. recorded beside a C. F. with a maximum of 18.8 of the efficiency of the twisting frame No accurate measurements could be secured but exhaust system on the single exhasiudsetsedoftwithsitserframe showed a dust simultaneous samples on both NES SEIS Som Spach ; 28 Rrica ete anaes we . gee sks ee C4 4 7S Coe 1 rh ae . - . . - ed Public Health Reports Reprint Na 1883 PLATE 111 rey -e*: eraques weny , BH 95-7 4 gsr ihn Fl le Ah 4B Od be see a *,Se d a at a . ue ae 1 wv 3 a yg a4 + ben sg . oe boca: . ye Ab were > eo - wow ae - Figure Tpexhausted broad loom en EDOe oe Figure Table for inspecting calendaring and brushing woven cloth - Wa Se oe ee Dos Se DUST CONTROL IN AN ASBESTOS PLANT , 13 concentration of 18.0 M. P. P. C. F. on the side toward the unex- hausted twisting frames and a concentration of 6.3 M. P. P. C. F. on the other side Four Foster winders spoolers were partially separated from the other operations by partitions fig 6 The exhaust system consisted of an individual conical hood around each spindle holder fig 8 Approximately 46.5 cfm were exhausted through each hood or a total of 9,270 cfm through the 200 boods on the 4 spooling frames Dust concentrations at the spoolers averaged 2.9 M. P. P. C. F. and increased to 9.6 M. P. P. C. F. within 30 minutes after the ventilation had been shut off WEAVING AND INSPECTION Cloth tape listing and brake bands were woven on different types of looms In this plant exhaust systems had been applied to the dry cloth looms since these were considered to be the most important source of dust The dust control program calls for installation of exhaust systems on dry tape listing and brake looms At present these operations are mainly performed wet or partially wet Brake looms were not in operation during this study Signifi- cant differences could not be noted between dust samples collected around the various tape and listing looms Dust concentrations ranged from 1.2 to 4.0 M. P. P. C. and averaged 3.0 M. P. C. F. Nineteen cloth looms were in operation in this department One of these was a wet loom not provided with exhaust hoods 4 were dry looms provided with exhaust hoods and the other 14 were so provided but could be operated either wet dry A loom without exhaust hoods is shown in figure 9. The exhaust system is shown schematically in figure 11. A double exhaust hood drew air from under the warp while a second bood was attached to the top of the loom lay with exhaust ducts running down the side of each picker arm to an airtight swing joint at the bottom The openings in the loom hood consisted of four alots nine inches long by 1 inch wide extending over a space of 4 feet across the woven fabric at right angles to the warp A total volume of approximately 10,500 cfm of air was exhausted from the 18 hooded looms This averaged about 560 cfm per loom but since it was seldom necessary to operate more than 10 dry looms at one time the average quantity of air exhausted was close to 1,000 cfm per loom Exhaust dampers were provided on all looms and a sufficient number to balance the system are closed on wet or idle looms The average dust exposure of a weaver operating a dry loom with exhaust was . bate 0.7 M. P. C. F. while the average exposure in wet weaving without veot exhaust was 2.6 M. Samples taken beside a dry loom . a without exhaust showed dust concentrations of 9.6 M. P. P. C. F. reBy fe Pee + :Gwe eh e etoses . te nie : al eat f 7 TTT TO a = Sr Pe . eee won eo PYF x EX ee TSE boveynp a AEA PESR 4 Ve Se . om Be ad we aah . hae aiind Sere are eas te, Eo eee oe a prt od wee etEe ws te wt. eee oe PAN. om we ry rad A - bt mA etee ee ne a ie -} 14 DUST CONTROL IN AN ASBESTOS PLANT , after 45 minutes Average dust concentrations during dry weaving have been shown as 49.7 M. P. P. C. F. 5 inspec Woven cloth was inspected brushed and calendered on the inspec tion table shown in figure 10. Each of the driven brushes was oe a car a OF == FIGURE Schematic views of exhaust system applied to broad looms partially enclosed and exhausted Approximately 750 cfm of air were the drawn through each of the two hoods at front of the table and about 200 c^>mwere drawn through the cleaning hood at the back of Pe) ( . . Do ~ . . . . 4 . * & a 2 e& ey mo dle ware . - bd ta - . 1 : : . DUST CONTROL IN AN ASBESTOS PLANT 15 the table Dust concentrations M. P. C. F. A sample taken across the table without benefit of tion of 11.8 M. P. P. F. during while a exhaust inspection averaged 0.5 roll of fabric was passed . showed a dust concentra- Doffing inspection and calendering of tape and listing were hand operations and were not provided with exhaust Dust concentrations of 5.0 M. P. C. F. were recorded during these operations but the exposure was intermittent Creelers had an average exposure of about 1.3 M. P. C. while placing spools and threading looms , An exhaust of 12,200 cfm of air was provided in the weaving department corresponding to approximately three air changes per hour In cold weather warm air was distributed through the department from a plenum system while in warm weather natural ventilation was secured through use of windows on all four sides of the department OTHER OPERATIONS Other operations in this plant consisted of processes in which the yarn was chemically treated and fabricated or processes for chemically treating or rubberizing fabricated cloth No potential asbestos bazard was associated with these processes with the exception of one braiding machine used to make large diameter asbestos tubing This machine was covered with a conical canopy bood about 6 feet in diameter which provided an exhaust of approximately 200 cfm of air A sample taken beside this machine showed a dust concentration of 0.4 M. P. C. F. at the operators breathing level Table Volumes of air exhausted per machine in various operations in an textile asbestos textile plant Total volume Just - Dust Dust code 00. ft./min ft./min M.P.P.C.F. | M.P.P.C.F. Asbestos opener Vibrating } 111-860 seTEED 700 Cotton opener Miting beds 1.023 Picker 0.22 Roving reopener ...... Fir lower and f.... neces Roving (2 625-1,000 625-1,000 i 3 1.160 ) 3 2.570 2 3 1,780 1 .800 LI 111-860 eer ea a? Joo. oS eee, weeb Se see * 1-10 142748 142748 meee, Roving Breaker primary primary _ Breaker primary . Wicking | Wicking card . a 1. 1. 420 4 440 3 120 272 121 Foster winders a 2.830 272 Foster spoolars winders spoolars *, __ Twisters broad loomlsooms Weaving broad ...... $ 111111 i 1,700 > 11.0 2 1.300 7 49.7 3 L850 ry 11.8 Uppoblabed through conveyor Equipped with pneumatic erbaur conveyor conveyor data other plants M. Dalla Fulton Rel f U. 6. P. not included H. 8. Individual cone for each spindle connected to exhaust manifold roy ee - - TIe S e e . = er _ 16 DUST CONTROL IN AN ASBESTOS PLANT SUMMARY exhaust Table 2 gives a summary of the operations provided with listing the number of exhaust ducts and the rate of ventilation machine as well as the average dust concentrations to which per are exposed Average dust operators concentrations measured near corte- sponding operations without exhaust are tabulated to show the effec- tiveness of the control methods which have been described CONCLUSION This study of actual results secured by a dust control in asbestos fabricating plant is presented program an control of an industrial hazard as an example of engineering Adequate data have not yet been published to justify the determination of threshold limits of dustiness which will produce asbestosis in any definite period of time In the absence of such threshold values it is not a^flblelimits of dustiness possible to determine permis ciable decrease in the on a medical basis Nevertheless any appre- amount of asbestos dust will cause a decrease in the incidence and severity of the resulting asbestosis The elimina- tion of all the dust in an industrial workroom is a physiological standpoint and usually economircaarlellyy niemcpersascatriycfarbloem Consequently actual atmospheric conditions in from the application of practical methods of dustancoinntdruolstcra ynrebseuulsuendg as temporary standards by that industry 6 REFERENCES Incf. NReiwesYoBr.kand19W3a7tson T. .: Engineering Geology John Wiley and Sons 2 Fulton W. B. Dooley A. Matthews J. L. and Houtz R. .: Part II The nature and amount of dust_encountered dust_encountered in Asbestosis 2p0la1nt9s35 Spec Bull No. 42 Pennsylvania Dept. of Labor anadsbeIsntdousstfrabyricSaetpitn.g Health 3 Bloomfield J. J. Industrial dust Pub . D. D. C. 1935 and Valle J. M The determination and control of Bull No. 217. Govt Printing Office Washington data 4 Barding L. A. and Willard A. C Heating ventilation and air tioning John Wiley and Sons Inc. New York 1932 condi 6 Unpublished United States Public Health Service Service 6 Higgins relation E. Lanza A. J. Laney F. B. and Rice G. B. Siliceous Siliceous dust in in to pulmonary disease among miners in the Jopia District Missouri Bull 132 U. Bureau of Mines 1917 Page 7 R. T micrometer Note on a new ocular micrometer for use in in dust Pub Health Rep 62 1315 1316 counting --