Document jy11bEK5RGd5KRmLE3yQrB1o9

3 5T H4 NATION A L S A F E T Y CONGRESS :.v^' 7*>. ' : . VOLUME V AUTOMOTIVE AND MACHINE SHOP SECTION ' '? J-** . 'IA<V^i` ll"Op At SAFETY OkH^sWACK ER B RI V E ;. W; ~ ?v`.? . f-; / 1- - .. C 0-U J H'C. - CH IC AGO 6V ItX. . ' : '. T-: o /> Automotive and Machine Shop Section " > ' ' ,' . ' '; ' . . ' Executive Committee 1947-1948 General Chairman--J. E. MOORE, Director of Safety, Corporate Service Incorported, Detroit, Mich. .' - '. /' ' Vice-Chairman--B. LOOMIS, Safety Engineer. Fisher Body--Ternstedt Division, General Motors Corporation, Detroit, Midi. C. A.. DeMONGE, Safety Director, Kdsey-Hayes . Wheel Company. Detroit; Mich. Secretary--D. L. McCULLY, Safety Supervisor, Westingfaouse Air Brake Company. Wilmerding;. Program Committee * Chairman: CEO. F, NUERNBERGER. Safety Engineer, A. B.. Dick Company. Chicago, HL^ R. D. HARVEY, Safety Engineer,/FJie Murray Corporation of America, Detroit, Michigan C. O. ENOCHS, $afety Director, fchevrolct Flint Division of General Motors Corporation. Flint, Michigan `1 F. H. HUMPHRIES, Manager Safety and Claims Division. American Car and Foandry Company, New York, N. Y. x. - ' Engineering' Commit! .. Chairman: F. W. FI5UE, Safety Diredor, The Brerrer Titchricr Corporation, Cortland, New YdttJ . . \ . r-> . BARNEY J.'POVOLNY, Safety Director, Detroit Diesel Engine JJlyisIon, General Motors Corporation, Detroit, Michigan *' . WM. SMITH, Director of Safety. Ford Motor Company of Dearborn, Michigan ; ... ' Mtmbuhip Commit!-- Chairman: PAUL J. BLACK. Safety Supervisor. Westingboose Eledxkt Corporation, Lima, Ohio . ARTHUR E. EWING, Latrobe Electric Steel Company, Latrobe, Pa. FRED C. YELTON, Safety Director, DdcotRcmy Division, General.Motors Corporation. Anderson; Indiana : ... ... Hows Letter Cotmnltl--' Chairman: PAUL F. BUNGER. Safety Director. Frigidaire Division. General Motors Cor- Yporation, Dayton, Ohio LOUIS A. GALANTUCCI, Safety Engineer, General Electric Company, Bloomfield. N. J. G. W. YEMM. Safety Director, Otis Elevator Company, Harrison, N. J. - Hoc dih. Commit!-- ,. . Chairman: A. L. BROOKS, M-D,, Medical Division. Tlsher Body Division, General Motors . C.Corporation, Detroit, Michigan ' . y'O; F; ENGEL, MJ>, Assistant Medical Director, Westingboose Electric Corporation. East vY`'''>PittsbBTgti, Pau-: ' . . . ' FRANK 'A. PATTY, Diretfor ofc Industrial Hygiene. Ccneral Motors Corporation. De- . trait, Michigan '' 5 6 35th National -Safety Congress, 1947- ` l . ^jPriaBcur Committor , .. Chairman: O. C. BOILEAU.`'Saperviaor of Safety. Health and Retirement. RilA. 'Victor Cor poration of America. Camden,;N. J. !` , v- . GERALD C. SQUIER Assistant Director of Personnel, Bulldog Electric Prodogs, Detroit. Michigan I V'k ' : "" <> ___ | -. ' * . . - : EDWARD G. HOLTZ.MAN., Dfirector of Safety and Medical. Depa rt ments,--W:---a--g--n-e--r--E--l-e:--ctric Corporation, St. Louis, Missouri Sfctflaficcd Commit!* A Chairman: H. J. JENNINGS, Safety Engineer, General Electric Company, West Lynn, Massa chusetts V W. E. BROWN, JR, Safety Director, The City Auto Stamping Company, Toledo, Ohio' LOYLE DAVIS, Director of Personnel and Industrial Relations. Mueller Company. De catur. Illinois / . . OfWt~Job CocnnBhbe ' - ' . . Chairman: M. P. BIANCARDI, Safety Engineer; Health and Safety Department. Industrial Relations, Dir, Allis Chalmers Company, Milwaukee, Wis.' ROBERT C. BENSON, Director of Personnel and Safety. Laming Stamping Company. Lansing, Michigan .) - E. CLARK WOODWARD, Director of Safety. A-O Smith Corporation. Milwankce. Wis consin Porter .Committee Chairman: CARL PETERSON. Safety Supervisor, Plymouth Motors Division of Chrysler Corporation, Detroit. Michigan `` '. . CARLTON R REID, Safety Engineer, Westinghousc Electric *and Manufacturing Com pany, Springfield, Massachusetts ] ; ` `. . HAROLD M. ERICKSON, Director of Safety, Nash Moton. Kenos^C^VU. . Manbarx-ct-Large--*]. W. YOUNG, Internatiocal Harvester Co, Chicago, 7. LEH*. MAN, Chrysler Corp, Detroit. Mkh-j *W. A, BECHILL,Chryikr Corp, Detroit, Mkh.; J. C. BOWER loti Mifflin Are, Pittsburgh, P14 *M- A. CLARK, 5557 Devonshire Rood., Grosse Pointe, Mich.; *H. B. DUFFUS, Weidiighocae Electric Coip, East Fittsbdrgh. Pa^ HOYT L. FRACHER, Detroit Steel Product* Co,iDcUoit.'MIdi4^'A^RUECHEN. MEISTER, Dominion Forge t Stampiiig Co^ WalkerrllR CARTHY, Fisher Body Detroit Dir, General Motors Corp^ Dctrott. Mkh4 ROBERTJL; SHAW, Detroit Diesd Engine Div, General Motors Corp, Detroit. Mki; LT.COMDR PAUL S. STRECKER; R F. THALNER Bukfc: MotorDir,' General'; ttoti^Tinpi; Flint, Mich.; *V. I. TROTTER; *C. E. WOOLIEVER6.'Smith wis. ' '' ' v3 -^vK Staff Xepraantativc--ARTHUR S. KELLY. National Safety Council,, Chicago, IIL " ` s Indicates Past General Chairman '' .... - ' Automotive and Mat'bine Sliop-Section 9 . . w* * ^ , ,: ,' < . brazing fluxes, some metals require fluxes disepmfore-assodated with metal fume fever conadning* significant quantities of fluoride may remit from such an exposure. - xxnpounds and fumes from these fluxes have been known to produce, significant nasal irri tation, Fluorides In general'are looked upon with suspicion since theupay. produce harm* ful effects, upon the ^ora^structure. A limit of a.5 mg. per cubic n^tojtas been suggested for fluorides; but no . standard has been agreed upon. Most industrial. hygienists at tempt to keep them as km as practicable in order to be absolutely certain that bone dam* age does' not occur among the workers. Where warranted 'the control of welding fumes is generally accomplished by providing a mechanical ventilation system. The type of ventilation used is dependent upon the na ture of the welding. When the object to be welded is positioned in a fixture or jig it is possible to obtain effective. control of the fumes by the use ofra, grill side hood, or flexible duct near the-sOuroc of fume. If the pans, are large and it Is necessary to weld more than a foot from a fixed point It is Silver solder Is one of the more common difficult to obtain good control.of the fume alloys used in fanning. Solders of this type with reasonable air- volumes through sys vary, in composition .-and may in some in* tem using flexible ducts. Since the effective stances ^contain cadmium which if volatilized range of most flexible ducts is approximately in sufficient quantities is considered to be 8 inches from the duct opening, it is neces harmful. At present the suggested limit for sary for the welder to move the duct when cadmium fume in air is r milligram per 10 ever the arc is outside this range. prac cubic meters of air. tical result is that most , ducts are\nqrmally Resistance, spot, or butt welding of plain not moved apd'tfac ventilation system does steel;is of no concern from the physiological not remove the fumes -when liberated. Ac standpoint. The fumes arising from such . cording to reports this type of system has operations generally ate caused by the vota* been effectively used in shipyards, for-the: rilized- oil which, has come upon the metal. control of welding fumes in confined areas. itodk during previous operations or which In vieW of this experience it should there has been plaiced upon the metal as a rust fore be a satisfactory means of control few preventive. , welding fumes in tanks; However, excellent The preceding dftcmskm of welding opera supervision and education is necessary to tions' has been based upon the. assumption make such systems effective. that the metals being welded are of plain Where the room volume per welder is large, steel. The performance of welding operations, the natural ventilation within the plant is either arc; , gas, or resistance, upon metals usually sufficient to prevent the.accumula which have been* coated with such toxic- ma- ' tion of excessive concentration of fumes from teriab as lotd, cadmium, or mercury may plain steel welding. Circulating fans directed cause harmful exposures. The beat crT-ihe from the side help to dilute the fume Which flame or of'the arc causes vobifllation^lof may be concentrated in the'breathing cone of there metals. Welding or cutting of terne-jrvthc welder.' V.y plate'ox.other metals containing significant ^' .: Another tbcafas of control, is the use of per- quandtfcsof lead can remit in the volatiliza- renal respiratory equipment. Air litre respira donofkadfiuhe, which if inhaled ,for a tors and fume respirators have been developed suffideni'period of rime, may-'result in lead which will provide adequate protection. Some absorption and ultimate poisoning. The cut* manufacturers of this type of equipment have ring or welding of surfaces which have been on the market welders' helmets with facilities coated with paint containing lead has caused for providing fresh sir to the wearer..Tbcjuse lead'pohdningjn.tbe past and will continue of this type of equipment has .boca liddtedL to -do wonte adequately ooottoHcd. Since the welder Is already burdened with Welding of cadmium plated material was helmet, goggles, and. protective dothing -he ' attributed -as the cause of . illness and even probably will not be receptive to a respirator. -death to a number of individuals during the It is usually, sufficient -in most welding for. recent',war activity. The reported cases in the employee to wear an ocdlnary helmet tmd dicated- that.dcath.occurred in a compara-. -to arrange, the position.of the work so as to tivdy short time after the exposure. prevent the concentrated fume from Bowing -*>Welding LOf galvanized . metal- causa the under the helmet. . . . . volat filiation of the zinc coating. Temporary Dry Grinding--The dust resulting from the 10 35th National Safety Congress, 1947 grinding of nontoxic metals which arc free of Machining--Smoke from oily parts is the sand l< generally comIdered a nuUancc and prevailing source of air contamination at it.not harmful per sc. Despite thU faa tome machining operations, jmecss has not been ifate laws require griding operations to be attributed to this type 6f exposure. As U the ventilated. This requirement has probably case with most- fumes and dusts of the nui been a hold over from the days when sand* sance variety little Is known as to what ef stone wheels were prevalent and also to pre fect, such materials have on already existing vent the creation of a nuisance condition. physical abnormalities. `. Grinding wheels in use in industry have ar Machining operations on steel produce tificial abrasives such as aluminum oxide or large chips-or turnings; consequently, dust ' silicon carbide. Emery, which is a natural is not a jirobfem. Operations involving the product composed of essentially aluminum machining of high lead alloys have been and the magnetic oxide of iron, may also be studied, and significant quantities of. air- $ used. A permissible limit of 50 million par- borne .lead have not been demomqated. tides per cubic Coot of air for aluminum Graphite which becomes airborne during oxide and silicon carbide was recently ac the machining of cast-iron is not considered cepted by~tbe members of the American Con ference^ of Governmental Industrial Hygien ists. Such a limit Is liberal and concentrations of suchSmagnltude arc normally not en countered. *. to be physiologically significant, and there fore is classified as a nuisance dual;. Frequently management considers it advisable to pro vide ventilatlop for the machine; which are productive of the moot dust, as gnphite on When lead, silica, or some similar toxic the clothing and person and surrounding material comes in contact with the grinding machinery is conducive to many complaints. wheel the exposure to the abrasive matter Ventilation systems' for the machining, drill may be Ignored and the exposure evaluated ing; and so*' forth, of cast iron should in on the basis of the toxic material. If this dude hoods located as near the cutters or latter materia] is controlled the nuisance will drills as is practicable. Many of these hoods also be eliminated. ,. are in use on production, machinery and are Ventilation systems for grinding /rheels doing an excellent job of dust control. ^ have been fairly well standardized'and gen Abrasive Cleaning--Since silica is recog erally are satisfactory to prevent a nuisance. nized as the most harmful of mineral dusts, Hoods should enclose the wheel as completely an adequate ventilation system is normally as is practicable. Air volumes should be pro provided at' the time of installation of com vided which axe sufficient to cause an inward mercially built sand blast equipment. Con flow into the bood when using the smallest tinuous usage and lack of maintenance result wheel. This is especially true where toxic in a breakdown of adequate control. Visible materials are involved. - , escape of dust is the bat evidence that this Wet Grinding--Baffles, hoods, and guards has occurred and it is advisable to correct axe generally located near wet grinding such a condition without undue delay... wheels to prevent dispersion , of the liquid Employees who are stationed in blast rooms used as a coolant. These devices lire usually are dependent, upon * personal respiratory sufficient to control the dust if it 4s/ nontoxic equipment. It is of utmost importance that in nature. If the dust liberated is toxic, roe- . such devices are of a type which will provide chanical exhaust ventilation may be required.' the necessary protection. Devices of this type Buffing and ' polishing--The buffing com-'1 pound applied to wheels used * for buffing and polishing vary in composition. Waxes and various types of-abrasive are the major components. These materials plus lint and fibers from the wheel are the essential In gredients of the airborne dust. The toxicity is- dependent upon the type of abrasive. . Generally ventilation is `provided so as to improve housekeeping and reduce the num ber of complaints and not because of the huard to health. . are of the supplied-air variety, and it is neces sary that the air provided be free of harmful contaminants. The air compressors should be located in an area free of contamination otherwise the contaminant will be transmitted to the helmet and the breathing, zone of the worker. . * *. >-- . ; y ` . Normally, ventilation within the.room-b ` provided so as to Improve visibility and to help prevent the escape of duk. to tbc.sur^ rounding areas not to reduce the concentra tion of silica dust to a. safelcvel, . . 1 Automotive and Machine Shop Section 11 Turablast or routing table type of sand Practically all industrial plants have open* - blast units should be provided with sufficient tions which involve the use1 of leading base entllatlon to prevent the escape of silica bearing metal ' or solder. Babbitt baring dust. Leakage due to excessive'wear should metal containing, approximately 75 per cent be remedied. lad has been encountered. The composi Small sand blast Cabinets, where the opera* tion jot solder metal '-is variable and de tor controls the blast nozzles from outside the< pendentupon the purpose Cor which It is cabinet, frequently have faulty seals around used, with ordinary soft solder containing a the door* or the rubber! gauntlets are loose comparatively high percentage of lead.,- . or tom. The dust which escapes from the . cabinet through these openings is in close proximity to the breathing zone of the cm* ploycc and in many instances exceeds the per missible limit for silica. This leakage should Assuming that the babbitt or* solder \n use is one containing a significant amounrof lead, the question then arises as to whether or not the employees working with this ma terial will become UL The answer to such a be corrected and'the men . should not be re question could be given by z qualified in quired to use respirators. dustrial hygienist after he had seen the opera If the articles being blasted are free of tion and considered such factors as the tem silica or other toxic material, the dust result perature to which the metal is hated, the ing from grit or shot blasting is classified in method of removing excess solder, the length the nuisance category. It follows that the of exposure, and the effectiveness of the con maintenance of ventilating systems for grit trol measures provided. . blasting, although desirable, is not always It is a well known fact that' lad causes so necessary as for sand blasting. illness if absorbed in excessive amounts, and The use of steel gr|l or shot in blasting therefore operations wherein lad . is used rooms produce -excessively high ooncentra- have received considerable * attention and 'wj of dust within the enclosure. It is there- study^iStH, of this experience certain prac >e, necessary-to-protect the worker.vVhbin tices art knbwn to produce excessive exposure the room. 'The"remaiks included in,sthe Sec whereas''t>ther. practices have been proved not tion devoted to sand blasting rooms attNhere- to be harmful: It. is generally conceded that fore; pertinent when considering rooms in excessive concentrations do not result from which steel grit of shot are used as the abra operations where solder is applied by mans sive. of an electric soldering iron. This is probably Vapor blasting, a variation of sand blasting, due to the small amounts of solder used and is bf comparatively recent development. This the comparatively km bat of the metal. procedure Involves-the use of fine silica and When an iron is/used which is-bated In a water under pressure. The silica used in vapor small gas fined furnace, the exposure may be blast units varies in size and may even be as of grater consequence. Solder which remains small as 1250 mesh (approximately to mi on the iron coming into contact with the crons). It Is generally believed that airborne flame or bat 1 vulnerable -for volatfliguion. silica partidcs bclow 5 microns are most rig* Small amounts of solder drop from the iron niScant in catuiftg silicosis. It then follows onto the hot Boor pf the furnace where it is that operations involving the use of silica radily volatilized or oxidized. The oxidized .-abrasive wjyosc initial particle size approached' 'material may become airborne due to dis that order of magnitude are more hazardous,' turbances crated by the flame or by remov and require continual vigilance in maintain ing or placing' the soldering iron in the fur ing good control. It is, therefore, essential that nace. Frequently industrial hygienist* recom the vapor blast cabinets be maintained so mend that ventilation be provided for bating that leakage of mist' docs not occur. Good units of this-type .thereby removing lad housekeeping is also essentia] as spillage of fumes and dust from the environment. This the. sand and water sludge upon the floor is particularly , true in small rooms or where '~^pl create a . source for .dust dissemination many units are in use. . ien - the. water evaporates. likewise, con The atmospheric contamination occariooed tainer* of the dried sludge should not be al by the use of either'gas or electrically hated lowed to *tand fn the factory vfhere they pots containing solder is dependent on a can be Influenced by air currer/tv of high number of factors. With higher temperatures vdodty. ........ .. more volatilization will occur and the rrratrr 12 35th Motional Safety Congress, 1947 will be the exposure. With the higher lera- Heat Treating-High temperatures 'are a perature the metal ii more readily oxidized to ' frequent source of complaint from employees produce a dross consisting of a high percent- in heat treat departments but such condi- age of lead oxide. The dross may provide a dons and thdr control are not within the protective coating to reduce the volatilization subject matter. under discussion.- . . of the lead; however, disturbance of this coating will create art exposure. As a safeguard against excessive contamination, pots contain ing solder or babbitt-are usually ventilated.' Wherever possible it is advisable to enclose the pot as completely as possible and provide sufficient air volume to overcome the thermal effects of the molten metal. Attempts have been made to use natural draft ventilation systems to control thee fumes and In those instances where the ducts were not of suffi Fume's dis' sem'inated fro.m cyanide p. ots are often associated, with cyanides used as fumi gants or as the lethal agent in death cham bers and supervision as well as rise employee becomes apprehensive. Fumes from such a source arc Irritating and because of this property should be adequately vdfttilatcd. The Irritant nature of the fume is caused by alkali formed upon decomposition of the cyanide. cient diameter the system was inadequate Molten lead is sometimes used 41s a harden A preferable method is the use of mechanical ing medium for metals. Frequently charcoal systems^` or some similar- material.is placed on 'the Thc/removil\of excess solder with power surface.of'the metal to conserve beat and driven Stools, such as grinding wheels, discs, prevent oxidation. A covering of this type or wire Wheels/creates airborne dust. which reduces the volatilization of lead while the may contaminate large areas of the factory bath Is quiescent, but has no effect.while the if the operation is extensive. Diligent use of bath Is In use.. Adequate venribirion should abrasive cloth will also result in excessive therefore be provided for baths of this type. concentrations of lead dust. Filing, however, As complete an enclosure as Is practical for is not productive of small particles and is the operation being performed is advisable preferred over the use of power driven tools. (with air quantities dependent upon Use open If filing is not practicable or feasible it will areas in the bood. To prevent contamination be necessary to provide some type of me resulting from volatillntloo of lead acaimu- chanical ventilation system for the solder re - taring in tbc combustion chambers the prod moval operations involving the use of power ucts of combustion- from gas fined lead pots tools. Since the permissible limit generally should be vented to tbc outdoors and not accepted for lead is- i. milligrams . be allowed to dhslpate Into'fhe worfcrooes.' ' cubic meters of air (555' cubic feet) it necessary to' have an effective system vide idcqualc co-rol Engines exptri^ m designing venlibuon sjttem. U> ~\Ircm Foundries--The principal Ingredients otfoundry dusts aresQicx,tea coed,days,usd parting ompdao*. He pmkeoimnt: B- bTde^dent ^^toptne toxic materials shouIld be consulted, otherwise a costly system might be erected and later discovered to bc entirdy ineffective. Fre quently solder removal operations require tbc use of portable tools on large objects and a o,f the.f*o_u__n_dry operation is-bring studied and what operation is bdhg performed...Tbc control of dust'Is tbc major problem, whereas fume is of secondary importance.- " . local exhaust system would not be effectfve. as ' A discussioo of alt tbc aspects of tbc in-, is the case in tbc fabrication of automobile dustrial hygiene problems, in'-jsuchvplants bodies. General contamination of. the'factory > would-require a separate treatise. For.' with lead duxihas been eliminated by .endos_ _____1 J____, _______________.1*______!__________I 1__________------------ present- discussion it should W .sufl-------------------------------------------------.W^.14 kJ ---- - ing the entire operation in a large booth and state that afl obvious soutocs. of dc exhausting a sufficient quantity of air from persion sboold. be reduced to a minimi the enclosure to insure a constant inward vadeq^atcV localized. exhaust vsyscemv- In\- a Bow of air from the factory into the. booth. mechanized foundry such places..wodld.be Under these circumstances no practical sand conditioning axxl' mixing equipment, amount of air;acould be removed.from the tumbling mills, shakeouts, coifc removal arid booth to reduce the lead concentration to a knockout stations, .' transfer' piihits- of .`-dry safe level, and .'therefore'it is necessary that sand, `abrasive'blasting operatibro, and';all the men. working, therein be provided with "grinding,,operations performed on . castings adequate personal protective devices.- containing appreciable quantities of sand. - Automotive and Machine Shop Section 13 .I . , '* Maintenance of ventilation equipment is Experience has shown that frequently pro a major Item in foundries because of the tective devices have been issued which do not abrasive action of.the dust. Tt la imperative provide adequate protection- Upon Inquiry that a good program be maintained to as to information was generally offcrnl that the keep the equipment functioning at maximum safety engineer was not too well Informed as efficiency. . to what should have been provided. . Because of the heat associated with large ThcJU^S. Bureau of Mines at tbeir experi scale foundry activities it Is a common sight mental station In Pittsburgh* tests equipment to see pedestal fans or air cooling ducu di of thlMype and studies the pjQte^ion^of- rected in ,such a manner as to create cross fered to the wearer. If thp^Kfl^tTmtlsfie^-' drafts which interfere with the efficient re tory. in performance, the^lwue ati^pproyil moval of the klurt dispersion. Better discre number to the manufacturet\whly appear^ tion in the placement of these fans or ducts on the device as well as thc'Utfntalner In'- will go far irt'`reducing dust concentrations which It Is received from the manufacturers. in the areas where they are used. The approval granted by the Bureau also After the obvious has been corrected, it Is stipulates that type of materials for which advisable that^ a survey of the foundry be it is approved. made by an jhdustrial hygienist so that an accurate evaluation of the exposure may-be obtained. \ ' " `v__ ) It has become general practice In the field! of industrial hygiene to recommend the use of only those respirators which have been ap Respiratory ^ Protective Devices -- As has proved by the Bureau. Safety engineer!; been stated, the - atmospheric concentration should likewise insist that -such devices be of dust and fume and other materials may procured and acquaint themselves with the be reduced to a safe level by adequate ex type of. protection afforded by each device haust ventilation. In some cases it is possible and thereby provide adequate control for the 10 correct the> condition by substituting a individual,-wearing the equipment. Some en less toodc material. If these, measures are not gineers prefer to stock only that type of res practical respiratory protective devices may pirator which will protect against the more be -used. Tbey^ may also prove valuable in harmful dusts or, fumes, since a respirator 61 giving protection duringan emergency or to this type will also give adequate protection provide protection for intermittent exposures for materials of.lower toxidty. The advan or to supplement other-methods of control. tage of such a procedure has merit as it re- They: should, however i;hbt ^se considered as .daces the types of devices needed in stock the desirable means ^cpRtrojQing a health and likewise insures the correct device Coir hazard. . *. the more serious exposures. Metal Cleaning ; By THOMAS MOONEY : Med-Fcrc Industrial Hygiene Txiboratories Tfe complete finishing of metals by elec troplating may.indodc: i;;?CJeffiQing by at t. ` PolishIxjg the base ^ 3. Cleaning with solvents. . 4.; Cleaning 'with Alkaline'solutions. . .5. 'Cleaning withadds, often referred to as 'v-Tfokllng.^'.' . 6.\MeaF deposition or electroplating. 7.!; Buffing the deposits. 8., Lacquering the finished product. In - abrasive cleaning, sand or sted shot is sued under pressurtjrbe potential health hazards in this type of cleaning afe exposure to dust of a high free silk*. (StO^ content caused by the sand andLaho to metallic dusts whereT'roetals capable: of producing toxic dusts are deaned by shot and rand blasting. Steel shot blas(ing is a, much kas severe health hazard than sand blasting: consequently, sted shot abrasive cleaning methods should be used wherever posdblc. . . - The maximum. allowable concentration* (M.A.C.) for free silk* are live million parti- Automotive and Machine Shop 17 scratches, before the petal is platted or paint- the area; All workers involved in metal fin ctL Tbe principal hannfa to health in metal ishing where lead Is used and ground with ) finishing are the dusts of toxic metals such power .tools -should be. required to wear a as lead, whlch^are used to fill hollow sur- metal fume respirator approved by the U. S. {aces when pbwhr grinding or disc machines Bureatr of Mines for lead dust, if the con are need to grind'them down to a .smooth centration of lead in the air is. 1.5 milligrams finish, as is often done in automobile fin per. ten cubic meters of air as determined ' ishing. . ' by test. The writer knows of do lead hazard! In operations of this kind, where the lead introduced when. finishing lead surfaces by surface is ground with power tools, the job hand filing.. . shoald' be isolated from other adjoining de-f ' REFERENCES partmems and hare suction applied to it to l. BlooafieM;' J- J-. and Blnm, Wm., "Health remove the fine lead particulate dusts from . Hazard*, In Chromium PUtin*." Public Health Re . 4J;;-23p (192*). Control of Solvent Exposures ' By E. C. BABNES Industrial Hygiene Engineer ' Westinghouse Electric Corporation The term "solvent** as used in industry mixtures are supplied to industry; In addi denote?]* variety of liquids that are used tion to this group of liquids which is avail mainfyrfbr tbc purpose of dicolving tome able to Industry' in huge quantities, there other material. The term is used rather loose are several thousand others which are avail ly and may indude such'liquids as water or able in quanthjpof a few -quarts or gallons. adds.; Although these are many; interesting Out of the'/miBv millions bOgaBons in floors involved in the proper control of all volved, tbc N|op-*otgank solventY which are types of solvents, perhaps the greatest con available In Urge quantities present the cern is attached to the organic tolvenuTand greatest' problem of control.. At the same this discussion will be limited to. that group time, this group- of solvents has been used of solvents generally referred to as "organic and studied sufficiently, so that reasonably solvents." Most of these solvents are pur good technical. information and methods c< chased to perform a spedfic function and. control .are available.`Manyof the several they`are later thrown away, usually'in the thousand organic solvents used in small quan form of a vapor. For example, a varnish may tities axe not so-well known and adequate be made by dissolving a min in toluol. The technical Information may not always be varnish is applied to some piece of equip available. They thus present a more diffi ment and-tbe toluol is 'then evaporated by cult problem in control. placing the equipment In an oven. Or, per In addition to these solvents which are'] haps it la desired to wash grease from mate now available,, there; are.probably at least metal ports. _The ports may be wet with the a doxen new organic solvents made, available solvent until the grease, ia removed and they in large quantities each year, and hundreds are theq allowed to dry. We'can almost gen of new searchts are made available In limited. eralize-and say that solvents are purchased quantitiei'-A continual check 00 new nuiV for th* express purpose of creating solvent rials and new processes fa therefore advis vapors.'These! vapocs create hazards which, able to be certain that the' uae^df new solv-. most' be'Controlled. . . . : , cuts will be adequately controlled. There are''about soo different organic When we speak .of controlling solvent ex solventa availablc In dram or tank'car quan posures,' yrt obviously- must Ihdude all the ,, tities. These solvents arc supplied to industry hazards associated with the use of the solv botH..a* a;.specific-chemical `compound and ent. We must-Indude.'such dements as. fire, ahoi-a?;*5 mixture'of ooc- or more of these explosion, and bcalth hazaixL When speaking ebemkal; compounds. Thousands of these of control, we; may ' fed 1 the' desirability of 18 35th National Safety Congress, 1947 establishing tome kind of an automatic con indicates whether the vapor is lighter or trol which would shut off or reduce the ex heavier- than air, and in cases where highly posure before hazardous conditions are creat concentrated vapors may fscape' from en ed. It would be nice if we had a thermostat closures, it. will be known whether these or regulator that would automatically, turn vapors will tend to flow downward.or up off the exposure before any hazard was ward through tbc air. You will note that 1 created. said "concentrated vapors." J should like to Automatic controls should obviously be emphasize this because there is frequently a applied wherever they are practical. For ex misunderstanding in connection with the In ample, combustible gas alarms may be used terpretation of the flow Of vapors of varying to control the explosion hazard in an oven densities. If there are only a few hundred being used to volatilize solvents. Automatic parts per million of. vapor in air, this mix- releases may be installed to actuate fire fight- lure will not tend to flow upward or down mg equipment the moment a fire *tarts. Un ward through the air when it is released, but fortunately, we do not have such a gadget will rather be carried along with whatever which can be attached to one of the work air currents may be present at the point ers to indicate when he is over-exposal ,, where it is released. You are all familiar with Other methods of controlling the human the high school chemistry experiment of exposures must be utilized, and these will, pouring carbon dioxide from one beaker into be discussed later. Essentially, control of another beaker containing a burning candle . solvent exposures must be based on preven . and the resultant extinguishment of the tion of hazardous exposures. In order to pre flame on the candle. If the carbon dioxide vent these exposures, certain technical in in the first beaker were diluted to a concen formation must be available. Equipment and tration qf only a few hundred parts per; mil processes must be properly designed. Finally,' lion of caxboin dioxide in air. it would not .quantitative measurements must be made to pour from the first beaker into the second establish the extent of the exposure. Perhaps but would be carried away with any air. cur- we should consider these three elements more reffis and rapidly diffused in the. surrounding carefully. * Before giving much consideration to the design of a piece of processing equipment or a air. Thus, any interpretation placed upon vapor density must take into consideration only thoie Vapors which have not been dilut manufacturing operation involving organic ed appreciably with air or otbex gases. solvents, a considerable amount of technical It is certainly desirable to know whether information must be available,. Such clemeu-. a solvent is flammable or non-flammable. If tary data as the boiling point; vapor; rprta-. the solvent bf noft-flunmabte. no spcdal con sure, vapor density,, fUmmabtlity, flash point, - sideration need be given to the possibility of explosive limits, corrosive action,, and .last: an explosion or the danger qf fire. If the but not least, the Maximum Allowable Con solvctti is' flammable,. however, spcdal con centration and skin irritation properties must sideration most be #ven to Its use so that be known. ' . the possibility, of ah urtcootrolls! fire or ex The boiling point of a liquid is of-Interest plosion may. not occur. Even though condi because it Indicates the temperature at which tions may be established for use of. the solv 5 Urge quantities of vapor will be given off at ent which minimize the fire or explosion haz ordinary atmospheric pressure. It also serves - ard, it is essential that a suitable type, of as a guide in estimating the volatility of a fire fighting equipment be made available in solvent. . .. case some accident should occur which would The vapor pressure of the liquid at room temperature, and also at any processing tem perature, is of importance because it indi- ' cates the possible concentrations, of solvent vapor that might be present under varying conditions. When' the. vapor pressure ; is known, the maximum vapor' concentration cause the solvent to born. Fire ..flirting equipment of a type suitable tor the specific solvent involved should be selected. Assuming that the proper fire fighting equipment has. been provided, it then becomes ncccasaryt to train a. suffident number of persons in' its .proper use. ' ' , .- i. that will be present under saturated condi* Assuming that, we are dealing vrith^a. flam tions can b<* calculated. ^, mable solvent, its flash point must.be known The vapor density is significant since it to properly evaluate the .means, of protection Automotive and Machine Shop Section 19 % -"Mch u required. The flash point of a flam- tablbhcd, using the four to one safety factor. >ie liquid is the lowest-liquid, temperature After installation of thi^equipment, actual at which enough vapors arc given off to form measurements are made jk> be certain that a flammable mixture of vapor in air imme the design conditions Have been met. diately above the liquid surface. If the liquid is above the flash point temperature, a small flame will ignite vapors from the liquid and they will continue to burn. Bdow this tem perature, a small flame passed over the sur face of the liquid will not ignite the vapors. In general, the corrosive action of organic solvents b not very, great. However, this fac tor must be known sb that suitable piping and processing equipment can be provided. We can thus be assured that a corroded pipe or piece of equipment will not fail and pro Where a solvent is constantly maintained at a temperature bdow its flash, point, there is not much -chance of it being - ignited by iparks or small flame. If. however, the solvent b at a temperature higher than its flash point, any small spark or flame near the sur face of the liquid will ignite it and the liquid will bum with increasing intensity. Thus, we see that a solvent whose flash point b above room temperature can be used without much danger of fire or explosion wherever the solvent remains at room temperature. If, however, its flash point b below room tem perature, care must betaken to avoid ignitCare must abo_.be taken to avoid the. station of explosive mixtures where thej navh point is lets than room temperature. In general; it can be said that when liquids are maintained at temperatures above their flash point, it is possible that explosive mixtures-of the vapor in air will be formed. c duce hazardous conditions. ' 4 ...The Maximum Allowable Concen tration and skin irritation properties of a solvent are part of the technical information which must be available if we are- to satbfactorily control exposures. We do not find . these properties listed in the handbooks the same as boiling point, vapor pressure, flash point, etc They ' are just as important, however, and must be furnished as a part of the tech nical information which must -be in the hands of people who are developing, design ing and operating processing equipment or - manufacturing, operations involving organic solvents. The Maximum Allowable Concen tration for different solvent vapors varies over a wide range--from a few partr. per million to thousands of parts per million. It is obvious that a piece of processing equip ment involving the use of a highly toxic solvent would, be designed quite differently The lower explosive limit of a gas or vapor than one using a solvent of low toxicity. b that concentration-of vapor in air, below . The need for providing engineers and su which an explosion cannot occur even though pervisors with all. essential technical, infor a 'source' of ignition is present. If we are mation-regarding solvents hak been 'empha operating an oven under conditions where sized. Perhapc it should be re-emphasized. explosive concentrations of solvents are pres All this information may be very helpful and ent*, then it requires only a spark or small useful if it is in .tbe- files of the safety en- flame' to came* a shattering explosion. Since ginccFtir tbe industrial hygiene engineer. It is difficult'to be certain that no spark or However, to be most useful; it must be in flame trill be present. It seems reasonable the hands of those persons who are actually that we should always operate this type of developing, designing or operating tbe proc equipment In such a way that the solvent esses which use these solvents. We have used vapors will always- be well bdow the lower several methods of supplying, suds informa explosive limit. Then we can be sure that if tion, which I will describe briefly. a spark, dr flame occun, there will be no pos All materials used in our plants are as sibility,of an explosion. We have fdt that it signed a material number. For each'material is desirable to maintain a four to one safety sctor?.oo, such exposures, and therefore we *hnlt;thc >apor conccntratkms In oven* or a' 4 x 6 card U written by our Headquarters Engineering Department. On each card they lbt the following Information-- . ` hdlar.;pieco>of-:procming equipment , to Material Number ' ( - *5;percent of the lower explosive limit. When Material Name . .. .. newf ^equipment V is r being designed, v the Caution. (A brief statement, of precautions amount of/solvent.' vjq>or to'. be released can to be observed In using this material) usually;, bercalculated, and. from . this the For Use By (Name: of. plant) r anKJunt of 'exhaujt .rentilatioo can be es- Furnished By (Name of. supplier) 20 35th National Safety Congress, 1947 Order From Supplier As (Supplier'* detig- limits, etc.' In each specification. More' re nation or catalog number) cently, wc are making reference in the speci Characteristic* (A brief statement of the properties or engineering characteristics of the material). fications to a Safe Practice Data Sheet. These Safe Practice Data. Sheets are provided'along, l with the process specifications to that-when Application (A brief statement of where the material b used and its general applica tion). . Specify As (How to spedfy the material on drawings or other written documents). You will note that the third item on thb material card b "caution." Before issuing any of these material cards, the Engineering Department .consults the Industrial Hygiene laboratory and they are furnished 'with a brief statement of the precautions that should be used for thb specific material. These sure brief statements such as "do not breathe va pors of thb material," or "avoid contact of thb material with the skin." Thb system has a person baa a process specification be also has a safe practice data sheet. The Sate Prac- lice Data Sheets list the following Informa tion about each, material that may involve any hazard-- ... ` Containers and Storage Properties Fire ' Explosion Breathing Swallowing * Skin Irritation * Personal Protective Equipment Precautions ' ' First Aid ' two advantages--first, it provides the Indus We fed that thb provides fundamental tech trial Hygiene Laboratory with Information nical information to all persons who are in about all new or changed materials that are volved in the design, 'development or opera used in the plants; second, a suitable warning tion of processing equipment. as to any hazards can be given. These ma terial cards are distributed to purchasing agents, materials and process engineers, de velopment laboratories, design and engineer ing departments and all other persons having a definite need for Information about mate rials. . We have made a. number of references to the "engineering design" of equipment or processes involving the use of organic solv ents. With complete technical information available, the designer of the equipment b in a good position to take- advantage of any special characteristics which a material may Another method that b used for providing have. He can utilize equipment and methods good technical information to the proper to suit the specific needs of the solvent in persons in the organization b the data which ' .votved. If bc.b dealing with a solvent which are famished with our Process Specifications. has a relatively low vapor pressure'and also Any process operation used at' any plant b a low order of toxidty, such'at kerosene, described on a; process specification. Each there may-be no need for totally endoetd process specification- b assigned a specific . equipment. If the solvent *1ris a 'relatively number, and in general it can be said that high , vapor pressure; and a .high, order of each of these process spedBottom describes toxidty, such as carbon disulfide, the design in detail any methods to bemused in prepar er will recognize that totally enclosed cqtrip- ing a specific Item or producfc^Jfdr example, \ roent fa eeential,. and in addition, local' ex one process specification may describe in de haust ventilaifoa wQl be required `wbcrcrcr tail the method to be used for insulating vapors might escape. In the second case, a armature ooib. and another may specify the oooriderabk. expenditure of money 'will be details of the method of molding rains. necessary for thb type of eqtdjpniexit. Before Issuing or revising any of these process specifications, our Headquarters En gineering Department sends a copy to our Industrial Hygiene Laboratory for approval. It U checked to be certain that wherever hazardous materials are used, a suitable warn* ing regarding the hazards has been Included. For a number of yean we included certain technical information such a Maximum Al- . inwsfdr Concentration, flash point.'explosive It b surprising'the number of solvent ex posures that can be eliminated by proper design'of equipment 'dr shop ;layout.'.Of course, if ,we;,fnberj[t a piece of equipment, or manufuturing methods hate not ..been originally, set up to. eliminate ,the solvent ex postures, some means of protection against the exposures'must be devbed.:3udi methods' as thcjnstallatton ^of; exhaust ventHating equipment, the use of'respIrators, or theap- Automotive and Machine Shop Section - `' 21 tlcatiori of hand creams1 nuy- be indicated, mcdmes these methods -of protection may be satisfactory. In general, however, they require.an abnormal amount of supervision. be used as such. They may not be related in any way to any harmful effect- of tbe solvent. The second general method of determining . an exposure of an employee to a solvent va Wherever relvcnts arc mod. it seems cxren- por is by a periodic physical examination. tbd that-some quantitative measurements be This method depends upon making . some made toestsblish the extent of the exposure. specific determination which will give an in We may hare good technical information and dication of early effects of the. solvent in the good engineering design, but we are never body. For example, blood counts, when certain'that we hate attained bur goal in properly performed, can be used to indicate controlling tbe solvent exposure unless the any early effects from exposure to a num actual exposure has been properly measured. ber of solvents, such as benzol. Other lab Tbe fire hazard can usually be determined by oratory tests may be made, depending on the - impectioa.-If there p any possibility of an type of injury reaction that may occur in the explosion hazard, the measurement of vapor body from a specific solvent. If we depend concentration by use of ooe of the readily upon physical examinations to determine available combustible gas indicators will de exposure to solvent vapors, they, obviously termine accurately whether satisfactory con must be 'done at rather frequent intervals, trol has been established. and the physical examination program must Unfortunately, it is a little more difficult continue indefinitely. to determine the exposure of a person. There I should like to emphasize the difference are two basic methods of determining the between these two general methods of con exposure of a person to a solvent. Tbe first trol. By making measurements which indicate is by some measurement or inspection. Tor the exact extent of any individual person's. ample, we may determine by measurement exposure, we are carrying out a procedure .DC concentration of solvent vapor in tbe air which gives an indication rot over-exposure w__h_e_r_e__ti_r_e_employ, ee worts, or an insp4 ection before there is any-hanoe for a harmful rc- may reveal whether there is-any contact of action to occur in. tbclemployee. When wc the solvent with the skin of the employee. depend solely upotKp^ysical examinations to Another method of determining the true ex determine these exposures, it is possible to posure of an employee b by some measure get an indication of over-exposure holy after ment whkh Indicates the amount of solvent some physiological change Ins takerrplaceJn vapor which has been breathed by the em tbe body. Tbe desirability of the first proce ployee daring`his working period. Exposure dure b obvious.. : ' to benzol, for example, mar be determined Even though we may not wish to utilize by a chemical , analysis of a urine specimen, tbe periodic physical examination as a means to determine the .ratio of organic sulfates to of controlling our solvent exposures, there is total sulfates In the urine. Some recent re- still a need for--proper pre-placement an^ carch wock Jndkates that it .win be pos- periodic'physical examinations. The pre- tible tb determine. tire- exposure of an cm- placement examination can indicate any ab- ployee to trichkrethytene vapors by a mess- normalities in an employee which later might urement qf the trichloracetic add in urine, be interpreted as the result of score solvent A number of solvents increase tbe rate of exposure.. Likewise, certain physiological excretion of glucuronic add In the urine, ^changes may take place in an employee dur- There-- methods have not been extensively fmgfshb period of employment, even though used, but certainly will find wider applica- C there has been no harmful exposure. It- b tlori- In tbe. future. -Wc have found it very { desirable to detea there unrelated changes helpful.In controlling benzol exposures to 'and make them known to the employee so determine the sulfate ratios In , tbe urine at that proper treatment can be Instituted and '>eriodk. Intervals, Whenever these determln- the employee will not have seeding that' tiqm indicate an excessive exposure, an In perhaps hb solvent exposure was a factor. vestigation fal Immediately made to determine To summarize briefly, there are a wide whyT such . exposure' exists -and -. to instigate, variety of! organic solvents used In Industry corrective-measures.. in relatively large quantities. From there sol v Ifibfauld like *to "emphasize that these are vents a tremendous quantity of solvent yapors metlreds of determining exposure and should are liberated. To control exposures , io- these