Document gbXpNyB2gYK9vQqjwnYr5R5yN

Revision oi 237.4-1941 _.- UDC 61?.63 Maximal Acceptable Concentration of Benzene _ -' . '7'fc C)0 . .- - . Sponsor .American Industrial Hygiene Associution Approved October 28, 1960 AMERICAN STANDARDS ASSOClATlON lNCORtOM1ED r .. American Standard Rtgtrfrird L`ntrrd SrotrJ f a f m f tifirrr A n Amcrican Staritlortl irnplics a conscnsus of tliosc airbatantiglly conccrncd with its SCO~JCniici provisions. T h e conacnsiis principle extcnds to thc initiation of work uiiclcr thr: proccdurc of tlic Association, to tim nrcthod of work to bc followcd, and to tlic fiiial approval ,of thc.stat?dard. :\a Aincricun Stanclartl is iiitcnclcd its it guidc to aid tlic manufacturer, thc `consuiiicr, and thr: gcncral public. `1Bc cxistcncc of an Amcrican Standard docs not in any rcspcct p r ~ ~ l u t al eny party who has approvcd of the standard from manufacturing, srlling, or iisiiig products, proccIIscs, or proccdurcs nut conforming to thc standard. . A n Anicrican Stanclartl clcfint~t product, process, or procerlurc with rcIcrcncc IO0rie or tnorc of tlic following: noincnclotiirc, composition, construction, clirucjiaions, tolt*raiaw, snfcty, tqwrating rliaractcristic3, Iwrfvriiiancc, qirality, rating, ccrtificntion, t(:r.tiiip, atid tlic scrvicc Ior which dcsignctl. ..ln:rricati Slarrrlards arc scihjccl to pcriodic rcviciu. T h y nrc rcaflirrried or rcvised I O rrievt c*lrrtrtf;irtgc?cononticconrlilions ~ I I 1I c~clinolnl;icnl progress. Users 01 Arricrican Slnrtdards arc cniclioncd lo J C C U ~ Clhc h c s l cdi1ion.s. Producers ot gtmls niaclc i n cmiforiiiily will1 an Arnci-icnii Staridard arc ciicour- aged to state on tlicir own rcsl)onsil)ilily iti iitlvcrtisinp, promotion nintcriiil, or on tags or Iabcla, tlint tlic ~ooclsarc procluccrl in conformity with particular Anicrican Standards. `I`hc inclusion i n such advcrtisi;ig anrl promotion mcdia, or on tags or labcls, of iri foriliation. co.iiccrning tlic cliaractcristics covcrcd by thc standard to dcfiiic its scopc is also cncuurogcd. ..- .. , I. .. ... .. .. -. ... . . B. Ainc:rican j:antlnrtl >laxinin1 ;\~:i~pt:iI~Clconcentration of Bcnzcnc, Z37.4-190, has b ~ m iclevelopcd .c;)tiiriiittcc, riiitioiial in scope. functit)iiiiig under the procedorc of tlic Anierican Standards Agsociation. e. ,I his comniittec: w:is c,rgiinirctI to co-ordinotc a11 available iiiformation 011 the various air con&tminants ai111to estnMisIi acccl~tnI~Iccoiicciitrations which could Ix iiscd i n t!ic JiveIopmcit of meails for controlling such coiitilniiiiatioii. `This stnnd$r(I o ~ ~i h cacccptaI)In conccritralion of benzene is one of a scrics of standards which linvc hcen prcparcd Ivy tlic w n i i i i i t t w a i d nppro\*c(lh y the American Standards Association. Tlic iriitinl draft of this st;tntl:ircl w;is prcpircd co-opcrativcly with tlic Lliiited States Public Heiiltli Scrvice. Thc first stantlard on this srrI)jitct wiis ii~)~~rovJti:idnunry 15, 1941. The stibcornrniltce which clcvclopcd the prescnt `revision of this stantlard wiis :tritlcr tlic cliairrnnnsliip of I-lcrvcy 11. Elkins. For riinny ycars the ricctl for staricI;irtI acceptill& coiiccritrations of tosic dusts, gases, mists, vapors, and fumcs i n tlic air of work pI:iccs lins 1)c:cri rccoyiizctl. A p : n t dcnl of information on such concentrations has Lccn puI)Iislicti, hut it fri:cliicntIy tIiITcrs, due largely to t h : lritryiiig coliclitions uiidcr which obscrvntions and tests wcrc matic. While rcsc:arcIi oti tlic losic I:ITCCIS or iiiaiiy cl:ists, fii1ncz+, iiiists, vnpors, antl p s c s is continuing in indusl try, ,~ovcrtiir~c:iitniIw t i t i i t i i i t l y , iiiiivi*rsitit:s, iind clscwlitw, tlic cniiccntriitioii .set forth i n this standard rcflccts informatioii obtained froin ill1 atitlioritativc: pu1~lislic.dd.iitii and tlic cxpcricticc of tlic mcmbcrs of the corninittee. Tlic ASA Scctioiial Coinniiltcc on Acccp:al)Ic Conccntriition of Toxic: Dusts and Gnscs, Z 3 i , which developed this stanclnrcl. hac1 the following personnel nt tlic tiiiic of approval: I!. H. SCIIRESCKlto. irnran DON D. IRlSIf, Vice-Cltnirrnnri I.1wnr C,. L A J I S~c,crcfnry 0rgnni:ntion Kcprcscrttrd Nnmo o/ /trprc.crnto:ic!e nntl lIcc.si:~essAliilintiorl E. S.;\merican Confwcncc trf (;ovrrtit~it*nta1 Intltirtriiil I1y~ienirt.r,. .J)n l l ~ l l l l ~ l l ~STiir;l?rc:t:1i, 1i . I'iil~lic Ilcalili Scrvica ..................Attrcrican I n t l i ~ s t r i ~I Il~ g i t * n r:\rweialiciti .I)n I~OllEllTI\. KEIIOC, Iliiivsrsitp of Cincinrinii I'IIIIJI* Dnisr;En. Ilarvnnl lliiivcrwily ( A h ) ................ ....\nirrican Instititti: of Cltrtrtical Etigirlr.i.r-. DII CAIICY1'. hlcCono, Linivcr$p of Micltigan (Aft) : I t . C. STIMTTOX. Travelers I n r i i r r n v n Conipiwy ` I'HOY. C. F. (;I!IISIIAM, 3licliigan S i r ~ c[Jniverrity (Air) Attivrican I't-trolciini Institii:c! .............................. AI.I..AS 1. 1)nni.w. Tltc Toms Gintiiany I)II I.ASISIO!I.NASIXSi.tn Oil Cnniliit~iy( A / / ) .......................Anicrican I'tililic llca1111 .4s*wi;t:iibt! .I111 1 ~ : J~. Cs IIAI.I.EY,(1. S. I'ttltlic ilcr~liltS r v i c c ......................Ameririin Society nf Safely Ettpinrw.~. .............`~\!zmc*iaiitinof Cawnlty antl Sort.:y (:iitttp:tttit**. \V~IIIII:XA. Coar, l!nivcr~iiy iif .\licJtigan . h l r l t o s A. SSEIJ.I.l;1rtf11r11Accitlcnt antl Inclernniiy Company F" E. 'I'iiv.vitm II:irifnrtl J\c:citlent nntl I n i l c n ~ n i t pCompany (All) ...................C;rrtatii;in ~tantiartis,~\irnt.i:cc:on f/.ittistiti) .DI: KISI:~I.EY KAY. I>i*pariniimt National IIcaItIi and Welfare Ctitifercctt*c:nf S~ntc?atit1 I'rot.icti~i:iI ....................I l r r d ~ I t;\iitItwiiiw of K i d :\mrrivn. ............................Inclt~itriii>j ltdic;il .:\smci:ition .I111 STA.\l.tY I I . O~IIIIIISSt.etc Dcpartnicttt of I l c a l i l i (Cnnnccticitt) .I)II C.AIIE1Y'. JIcCo~it)U, nivcrsiiy of Michigan DII A. .I.I..ASSZewAY.ork University ( A h ) ~ ....l n ~ ~ r n a ~ i ~:\zirntwi i~atlinn t * f ( h w i i w v ~ ~ i 1t .laI)tir .Of!i~~i;tl-. I I E I ~ ~ E 1Y1. I~I.KI3Sla~Sea,cl111scttDr epnrtnicnt of Iahor & Inclustries ......................3lat1ttl;lcillririp Clit:tni~:s' :\**oci;liiem .nil Jolts 11. For:i.cett. E. I. t l i i I'mt do Ncrnoiin and Cnntprny. I n c ........National ;\s.wciniion or 31ttttt:iI C;t~tt:tI~Cy ont;int~it.~. Fit ASK S. l.o\v, F t w I hlacltiiic!r). and Clicniical Corporation ( A h ) .IhC. 1:. \YII.LI.AMS, I.iltcrtr >Liiitrl Ittcumncc Company CIIAIII.Y-* S. 1.Auni.y. I.cinilictriticnr rlfit~ualCrrnalty Contpany ( A h ) National . h f c t y Caiitrtcil ...................................Fitl:Itwrc:r; \V.S.\sns, Uniit*cl S~aIcsltiiiiltcr Company .....................I!. S.Dcparintcnt of 111c:\rmy (/.inison) K. I\. KKLWS (.4Ir) FIIWKIIICK11. I ~ I S I I O F F I!. S. Dcpn 1'111,IirI r l lmcnt nf c u l ~ l iSc llt*aItlt. Etltira rvirr (/.itci.wn) t.i.ti.n..i.tn..il..\.V.d.f.:t.rt.*.......... .Ihr 11mitnT E. STIWISI:KR Iln W. ( h n r C m i w (.-fh) i ! Contents .. SECTION 1'41x ..1lit: 3lc;itiittg of ~ c..- I. 1 ; ~ ~ i ,t\c~cc~pito~l)Il~:Cunccntrnticw ........................................ 0 1. Svi~iwatid I'urpow.. .............................................................. 7I 2. l ' r o i w t i c u d 1k:nrccte............................................................... 7 5.1 CcticritI I'roiwrtics ........................................................... 7 . 2.2 Pli~~icnl-Cl~r:nl~'ireiap~rtks ....... :......... i ................................. 94 2.3 `I'oxic I'rolwrtics ............................................................. 7 .. 3. hlit si i t i d hccciiInlile a. Coticcti t rati o t I ......................................... s t . Smipiittg l'rocctlorc atid Analytical k;lc~lii~!.:.:.. ....................................... 7 4.1 Sompliag Procctlurc .......................................................... 7 4.2 Ariiilyticol hlctltotls ........................................................... !I . 1 . I~cfcrcnccs!::th~e Tat. ................................................................. 9 Gctieral itfercticcs .................................................................... 9 ...... Tlic Mcaning of Rlssilnal ~'AcccptnbleConcentration . .-... 4 ~t is gcricrally rccogiiizc(1 tliat tlicrc arc' ~ c v c ~ofs coticcntrntioti of atnior;plii*riccoiltaminants 10 tvliicli i~ person may Le exposed witllout .known ill cflccts or tlisconifort. Sincc'it is not prnctical to maintain coniI)It:tcly uticoritaniinatcd air i n most industrial situa. titms, it is ncccssnry to cstalligli mnximal acccptalle conccntratiorrs o l atmosplicric contaniinniils ciicomtcrntl in ititlustrial operations. 'I'lic~t: coricuntrations i n tlicmsclvcs do riot rclircsc:lit n scnlc (it rclntivc ttlsicity; thcy represent tlic coiiccntrations of con. tnrrrinants Lclow rvlricll ill cflcctJ itrc trnlikcly to bc csl)i:ricncctl I)y nriy Lut hypcrsiisccptiblc individuals. ,.I I ~ s ctrflcc:ritriitions ilrc ~ I S U ; I I I ~ L ~ c dupon data ol)taiiic:cI l q otic o r riiorc of t h followiilg proccdtircs: i1) 1,aI)orntory tosts on nniriials 12) 1,nl)orntory tcsts [!sing huriinn strl)ji!cts (3) Erivironiiicntnl nnd iiicdical invcstigations i n plnllts .'I coiiiinoii fcnturc of thcsc proccdures is tlint the t:xpcrimcntnI csposurc sIinII correspond. t.o thc nornial work pnttcrn. This shoulcl bc takcn into consitlcrotion ;iIm in thc application of maximal ncccptnblc COTIwritrotion valuc~. , 'fhrcc critcrin h a w govcriicd the cstnljlisliincrit, of . tlicsc conccntrntions: (1) Organic or othcr tissuc cllangcs (2) Fur;;:rionnl rcactions that hnvc no disccrnillc ui:tn\\-?;rd clTects on hcaltli ljnt CBUSC impairmcnts, sucli ns in-eo-ordinntions nnd incrcoscd proncncss to nccitlcnts (3) Discomfort o r advcrsc scnsory cffccts In thosc cases in which thc coaccntmtions liavc 1 ) L m cstnblishcd on thc bneis of. organic changcs, it is logical to assurnc that rcpeatcd exposure to conccntrations significantly in cxccss of tlic acceptable cancr:ritration probably woul~lproduce injury. When the lavcl has bcen establishccl on thc basis of a functionnl change or discomfort, it is logica.l .to assume that cxposure to concentrations not grcatly cxcccding thc ncccptable concentration wotild not produce matcrially injurious effccts. Hencc it is important to undcrstaiid tlic CritcriCtipon w Iiicti any sucli iiiisirnal , ilcccptiiblc coriccntratioii has h e n cstablishcd. Tliough tlic purpose of tlic acccptaijlc conccntratioii is to rniniiiiizc Iicattti Iinznriis, its initncdiate usc is for giiidnncc i n cstnLIisliing cnginccring procedures . to prcvciit objcctionallc conccntrations of toxic or riosious riintcrials from I)citis prcscnt in the air of work placcs. Cotiiparison of tlic rcsults of air annlyscs with tnuxinial acccptalh conccntrations indicate-. ~ iiccq~!;iIiIi: conditiolis or otlierwisc tlic ncctl, cstcnt, * ; i t i d tir;i!ri(:y of coqtrol iiicn,yrcs. Sampling and ; i i i n I y i s sIiouIcI I)c pcrforriictI L y 'conipctcnt pcrsonncl using :iii iict:(:jit;il)lc riictliotl tlint will provide a rcli;il)lc riicasurc of actual csposiirc. * I\ir nii;ily~csi n conjuiiction w i t h acccptnlilc conc.mtrnlioris of such ntniosplicric contamiriaiits as arc ciicowitcwil i n idustriiil opcrations scrvc as a iiicnsurc (if csposiirc, I)ut riot ns n iiicans of diagnosis of occupntionnl tlisciisc. ljinglioscs dioul(1 !x bascd rtii a consitlcrntion o l all factor$, including rcsults from clinical niid physical csnminntion, as well as , from-ia1r anidyscs, from nicnns of asscssing amounts nf matcrials in tlic body, and a knowlcdgc of toxicological circcts of tlic matcrin~sunder considcration. I n tlic applicnt!ort of tlic standards, it should be kcpt i n mirid that: (1) Tlic acccptablc conccntra:ions scrvc as stand. iirtls for good industrial Iiygicnc practicc. ( 2 ) Tlicy serve as cnginccring guides. Design and operation ::tiould aini at maintaining all concentra-. tions LcIow thc hcccptaI,Ic masimum. . (3) Tlicy sliould Iic n;ipliccl and iiitcrpretcd"by coinpctcnt individuals with a fulI undctstnnding of . tlic basis atid limitations of the information from wtrich thc standard Iins bccn. devclopcd. . ( 4 ) It is-advised that thcsc standards arc con- sidcrcd to bc guitlcs townrd good industrial hygiene and ore not,inten$d as Icgal rcquircmcnts. ( 5 ) The lcvels h ' a p p l i c a b l c only for cxposure to a singlc substance. In the case of cxposure to mixturcs, thc cITcct may bc increased or decreased, and controls should be based on thc specific situation. L. 4: _. .' G - .. American Standard b Masimal Acceptable Concentration of . Benzene 1. Scopc and Purposc 1.1 `I'hc rnaxinial acccptablc conccntration of 1)r.n. zciic applies lo all placcs of cmploynicnt. 1.2 TIICp u r p s c of this stan&rtl is 10 pruscribc t)lc ni;lxir:in] acccptablc concentration of tenzcnc in thc atmorplicrc of work placcs for guidancc in design and opcration, so as to protcct thc healtli of tlic workcrs. lating wliitc bloorl cclls, platclctr, and red blood cclls. Individual swccptibility varirr greatly. Absorhcd Lcn:nnc is cxcrctcd partly as plienol conjugatcd with sulfntc i n tlic urinc. Dctcrmination of thc ratio of iiiorpiiic In total sulciitcs in the urinc is ;I U S C f d lllcthd Of EJlillialing hllZcliC CXpOJUrC [41. h l r ~ i c dcontrol proccdurir should cmphaairc pc. riodic blood examinations. * 2. Propcr!ics of Bcnzciic [l] * 3. J I a s i ~ n n lAcccptnl)lc Concentration 2. I G!ncrd I'ropcrties. Dcnxcqc (bcntol) is tIir lowtut lioninlopuc of thc aromatic liydrocarbons. 11 sliaultl nnt 1)c c o n f i l d with bcnxinc (benzin), a mix. t u r o mainly of aliphatic hydrocnrl,ons. Dcnzcnc is n ~ ~ ~ I c ~ rliIcicusidi. Coninicrcid bcntciic is zcldom purc and may' hc coritnrniiiatccl with xylcnc, tolucric. plicnnl, tliioplicnc, carbon disulfide, acctoiiitritc, and also by pyridinc and athcr sub,.tams: 2.2 I'liysicnl.Clrcmicn1 Propertiiv Clicinicat.. formula: Csll1; I\lOlL.XUlPr WCiSht : iC. 11 . [21 Spccific gravity: . 0.279 at-2c0 4 -Vapor clcnsity (air 1.00) : ' noiring point: .. 3lclting point: 8 Vapor prcssiirc at 26.1 C: 2.7 m.1 c . 5.5. c 100mm Hg (milli- mctcrs of mcrcury) Flarli point (closed cup) : -11 C (12 F) . Explosivc limits (pcrccnt 3.1 Tlic maxirnnl acccptablc conccntrotion of IwnZL`IIC ( l ~ c t i ~ oslh) all hc: 23 Itarts pcr 1, O U O , O O O ~ ~ . ~o. ~fS ;iir l)y tuliittit:, (!i~rri.~iif)iiiltioIi~0.08 ing (milligrnrn) . pcr litcr at 25 C :itid i ( j O ~ t i n ilr.t!ssitrc, for csposurcs . not cxcccding a tola1 of. G r1out-s p r Jay, with tlic. . ttndcrstanding that t w i n 1 ions i n conccntrntiori ahoul'd .' ` fluctuate below this lurcl. 3.2 Tlic maximal ncccptalh: concentration of Icn. zcnc is i i l ~ e don field s t a c ~ i min plants wticrc bcnzcns poisoning tias occurrrd. Scrims caics of Lcnzcne poisnning Ilavc h n rcportcd srhcrc conucntrations tircragcd 1.50 ppm (parts pcr million) [SI, 103 ppiti. IGI, 100 ppin (3 cascs) [ i ] a,nd 60 ppm (81. Blood rliangcs wcrc found in wotkcrs cxposcd to averagc ronccnlrations of 100 ppni arid !IO pprn (91, 80 p p I .;I, 105 ppii [GI, and GO ppni [a]. Thc conccntration of% ppm is intcndcd to provide tlic averagc individual with a considcratlc margin of sdcty asainst scrious hcntcnc poisoning. A nicdicnl conrrol program is rccornmcndcd xiicncvcr workcrs arc expdscd to canccntrntions of bcrizcnc vapor approactring tlrc maxiiiial acccptablc eanccntration. by volumc in nir) : 1.4-7.1 ~31 ..;Autoignition tcmlwrature: 562 C (10.M F) , 2.3 T&fc Piapcrties Bcntene absorption. occurs mainly through inhalation of t h i vapor. Upon acutc cxpoiurc, benzene acts prcdominantly as a narcotic, causing dcprcssion of the central nervous system. With chronic cxposure, bexzene may cause bone- marrow damage, resulting in a change in the circu: .Nitmben in brackcb throughout ihc tcxt refer to cor. raponcling numbers in Rcfcrencea .on P.RC 9. . 4.. Sampling Proccdurc and AnoIytical BIetho(1s 4.1 Sonipling Procecliirc 4.1.1 The sampling proccdurc zhal1 be in accord. ancc with what expricncc shows is ncccstary to sccurc a sample-which is trttfy representative of the acttia! working conditions at the location tested and /or the period 01 the employed daily exposure. Thii impliea that the d u m e of the sample and &e rate at which it is drawn into the sampling apparatus shall -7 ,. z37.4 .-- .3 tlinitrol)cnterrc I Jth~e action of fuming nitric acid and conecntratctf sulfuric acid. Thc sample may bc taken originally by passing the air through such a nitrutins niixturc, in a s u i t ~ b l cbubbler, at a rate of 0.02 to 0.25 liters p:r iiiitiutc [101;or grab sampler niay bc Lakcti in Suitiihlc r ~ ~ c p t n c l cansd then shaken w i ~ l initrating acid [ 11); or tlic air may he passaccl w c r silica gilt awl the latter licntccl in tlic IaLoratory t o clriw u:f tlie I)e~izeiie,which is 1 ) a s ~ ~ 'tdhrougii ..nitrating acid. 1lie ditiitro1n:nretic m;ry he dctcrminml by the c o ~ n rprotlucctl ~ i ynictiiy~e;try~tetonc anct alkali. Any otlictr at!iilstical metliocl may IN? UILYI,pro- vicltnl it is cciuivulent i n applical~ilityotic1 relia1)ility I O l l l l l ~cited SOTE: I t is iitiili*rs1iniil 11131 tlic mupliiig and analy4n of wiitaiiiiiiiitril air e- gwciliivl ~IWJaVt11I1:1,1iit inti-r1m*1alim of 11iv &IIY in rvliitiiiti to IIIV s ~ a i i * i I pi~riiii+sililecoiiwiitration rli:tll IN: ilirnt. only Iiy ti*i*liiiicaIly qi1;LlificiI ant1 cornliclrnt ~ll*l-e~llu. f .. -._ . . . . . . .. , 237.4 _. . 9 Refcrcnccs to the Test ! Gcnercil References Ihtonsrsc. E m EL. I'cisici~yoi Itrdustrint Organic ( Itcnzol) poisoniag in thc rotogravure printing Srdiwnts. Ih-iserl ilmcrican crl. Ncw . York : industry i n Kew York City. Jorcrnal o/ Indus: Cticrnicnl 1'ul)lishing Compnny, Inc, 19.33. [ r i d 11ygicne and Tosicology, vol 21, 1939, p * ' D.iv~s,P. A. Tosicity of benzcnc. Journnl of fltc 395. Amcricnn rlledical A.r.socintiorr, vol 114. 19:iO. II.iaitr.Tos, ALICE and II~RDT, ~ I R I E TL. InrIusrrin1 pp 553.5.5i. F.imll.\m, LAWRESCTE. IncZu.ttria1 To.ric4ology. 2cl 9b.ricolopy. 2d cd. Sew York: Paul B. I-Iorbcr, Inc, 1949. ed. I3altiniorc: The Williams ant1 Wilkiiis Com- HESDERSONY, . and 1I.icc.mn.H. W;Noxious Gasr..c pany, 1957. and the Principles of Itcspiration Influencing Fire-llnmrd Properties of Flammatle LiquiLs, Gases Their Aclion. 2d ed. N e w York: Rcinliold Pub- and Volnlile Solids. Boston: Nationnl Firc Pro. tection Association. 1954 (NFPA Bo. 325). lishing Corporation, 1913. PATTI-.FRhSK A., ed. industrial Hygiene ntrd T0.1-i- Flnmmnblc Liquids nnrl Gases. (The A`ational Fire cokogy, vnl IT. Kcw York: Interwicnce Puhlislt- Codes, vol I.) Bostodi: National Fire Protcc- ers, Inc, 1939. tion Association, 1958. \*os OETTINCEWN,. F. Toxicity anti Potential Dangers G R E E S ~ E RLC~, os.4nnB. cn:ol Poisoning ns an Itidus- of Alipltatic and Aromatic iyrlrocarbons. trial /In:nrd. Washington, D. C. : Govcrnl*mt Washington,`D. C. :Goccrnrnent Printing Oficc. I'riqting Ollicc. 192G (US.Pul)lic Ilcaltl: i're- 19-40 (US.Public Ilcaltli Service Bullc,tin KO. ports, Rcpritit No. IO%, pp 1337-137.5. 1410- 2.3s). 1491, 1516-1533, July 2, 9, 23). STULLD,'. 11. Vapor p r c s u r r of pure sulwtan-cs- GREESRERCL,EOSARDM: AYERBSI,AY R.; COLDWATER. nrgonic compounds. Indrcstrin! m? Enpncering L~o?i,\nn;nnd SJIITIT, I\DELilI)E It. Bcnzcnt- Clrcmttry, vol 39. 19ti. 1) 517. U American Standards The standtrrd in this booklet i s one of over 1950 standards approved to date by the American Standards Association, Incorporated. . The ASA. provides the machincry for creating voluntary standards. It serves to eliminate duplfcation of standards activilies and to weld conflicting standards into single, nationally accepted standards under the designation "American Standard." Each standard represents general agreement among maker, scller, ,and user groups. s to the best current practice with regard to some spcdic problcm. Thus the completed stqndards cut across tho whole fabric of production, distribution, and consumption of goods and services. Manufacturers, consumers, technical -orgonitationf, and governhental agencies all substantially interested and -affectod groups are represented on the committees which develop and regu- larly revise American Standords. The completed standards are used widely by industry and commerce and often by municipal, stale, and federal governments. The ASA, under whose auspices this work i s being done, i s the' American clearinghouse for standords activity on the notional level. Founded in 1918, i t i s a federation of more than 100 trade associations, technical societies, professional groups, and consumer organizations, Some 2200 companies are off iliated with the ASA as company members. ASA i s the United States member of tho International Oiganizotion for Stand- ardization (60)T.hrough this channel American industry makes i l s .position felt on the.international level. Americin Standards are on file in the libraries of the national standards bodies of m'ore than 40 countries. For a free list of 011 American Standards or information about membership in the ASA write: AMERICAN STANDARDS ASSOCIATION INCORPORATED 10 EAST 40th STREET NEW YORK 16, NEW YORK 6 ... f ..