Document B5Mz5MnLNp3dnGk8LMd0ORDyE

< ' WEDNESDAY AFTERNOON SESSION October 16,1935 The session was called, to order by Chairman, Irwin W. Millard,, president," Industrial Gloves Corporation, Danville^Tll. Chairman Millard mentioned some of * the problems of providing adequate safety equipment for industry. . . ... '. ' .cs. . ;. ' RespiratoryProtective Devices - ', l (An interpretation of the U. S. Bureau of Mines; Schedule 21) By CARLTON E. BROWN, Chemist, and . WILLIAM P. VANT, Supervising Chemist Gat Section, Pittsburgh Experiment Station, Pittsburgh, . Pa. >. The respiratory protective devices of industrial hygienic importance are those designed-to protect against-.the Inhalation of harmful solid, gaseous, or. liquid atmos- . pheric contaminants, or the inhalation of air deficient in oxygen.' gas masks for protection against,the inhalationx5P"gases and vapors; 'oxygen breath ing apparatus,/hose masks, and air-line respirators for protection against the inhalation -of any atmosphere provided it does not contauuHarmful constituent which can be1 Aabsorbedireadily through the skin; and the abrasive blasting helmet or hood for pro tection against the inhalation of and the.impact and abrasion from the atmospheric particulate; matter-generated in sand blasting or abrasive blasting-with steel shot . V These', devices are designed to furnish protection either by making the wearer's inspirecLair safe to breathe or by supplying the wearer.with safe air.Irom a supply. which he carries or from outside the contaminated zone. .. The .wearer*of the first or air-purifying type, on inspiration draws air from nis -immediate" surroundings ' through the device which either removes the contaminant," .-usually by chemical or mechanical filtration, or converts it into a harmless substance. -This type, .of course, offers no protection against atmospheres deficient in oxygent as it does not add oxygen to the air; - *. - There are twd types of respiratory protective devices of the second type designed to supply, the wearer with safe air. In one, the wearer receives his air .supply from a cylinder' of compressed oxygen, liquid oxygen, liquid air, or from a chemical which - yields oxygen upon decomposition; This air supply .is part of the self-contained unit, 'all of which is carried by the wearer. In the other type a hose, attached ..to a face piece, is connected to a compressor or blower whose intake is located in safe air.. Air is forced through the hose to the wearer. Note: Published by permission of Director,' U. S. Bureau of Mines, (Not subject to ci . right.) '' <, ' 133 . '.T - . TC 3 (AJV-QISSIO 134, Twenty-fourth Annual Safety.Cohgress---National Safety Council . There is someconfusionlntheuseof the term "respirator " ic/designate' devicis for protection against the inhalationof atmospheric rpartictote matter. Such devices / were the first and for alongtimewere the only respiratory protertive devices;' They were logically called respirators;, and as long as they; werevthe 6iUy devic^S^.o ttus k|nd there was do confusion. The development of other/devicesof industrial hygieciic .. importance and the development of ddvios for, mainto'ning^fartfficialjrespiratioh over long periods and for enabling men trapped in submerged submarines to reach the-'siir-' . face safely, all called respirators, was .responsiblefor*thie confusion. ; The:Bureau of Mines,suggests, that the:term "resmratori' be retainedfor.all of these, devices,Vbnt that respiratory protective devices of industrial hygienic importance be called inaus- trial respirators' and that , the different kindsof industrial .respirators be ^signed a name which will indicate their operating principle or field, of: use or both. Satisfac- - tory names in common use should be retained.,; On this basis, the' Bureau of Mines suggests tile following classification-for'respiratory protective.devices of industrial hygienic importance: ? Industrial Respirators h 1. Supplied-Air Respirators;1 ^ a. Self-contained type (1)'Oxygen-breathing apparatus* b. Hose -type (1) Hose mask ^ (2) Air-line respirator* . (3) Abrasive blasting respirator . 2. Air-Purifying Respirators a. Chemical filter respirator*?; * . r;. (1) Add gas orjtypeA* chemical filter respirator ' (2) Organic vapor or type B* chemical filter respirator . (3)' Ammonia or type C* chemical* filter respirator (4) Carbon monoxide of,type D chemical filter fespirator b. Mechanical filter respirator' - (1) Dust or type A"; mechanical filter, respirator (2) Fume or type B^ mechanical filter fespirator X3). Mist omtypfe C'-mechanical filter respirator - c Starve ,. '4 V . r- " Testing, and. Approving of Industrial Respirators by the U.-'S. Bureau of Mines Since its organization the U. S. Bureau of Mines has. been.interested in industrial ' respirators as a means of protecting workers, in the mineral industry against harmfdl atmospheric. contaminants. - To tills end tiie Bureau has developed an approval , system, thppurposes of which are:' (1) To encourage andaid manufacturers in the develop ment and marketing'of safe and suitable equipment: and (2) to encourage, the'.con sumer to use such equipment, to aid'him in o^tainfog it did to instruct him in its. usage; These purpose! are accomplished by establishing!a schedule of the material and performance requirements that a safe and suitable device should meet; biy making approval tests for conformance to such a* schedule; and by informing the public.of the. . Sometimes called mine rescue breathing,^apparatus. '` * Sometimes called paint-spray. respirator or positive pressure respirator. Sometimes called sand-blast, helmet or hood. * Commonly called gas mask. Letters assigned'to canisters of chemical filter respirators.. .See U. S. Bureau of Mines ; Approval Sched. HD; Procedure for Testing :Gas Masks lor Permissibility,. 17 pp.,.1935. f Commonly called respirator. Sometimes referred to as dust. respirator or mechanical fitter-type respirator. * Letters assigned to mechanical filter .-respirator filters. See TJ. S. Bureau of Mines Approval Sched. 21, Procedure for Testing Filter-Type Bust, Fume, and Mist- Respirators .for. Permissibility, 14 pp,, 19J4, , S'The devices now referred to as Type If or Altr Service Gas Made and. the chemical cartridge respirator fall under this heading. ^ ' < ' . feV;'-**-'. WP -.-.. ' ,-"-V;*.`\:V'- './'' .',;' 1355 ady^^^Jin.^e-tKe; of; deyicesbeatTag.;Breauof;Min,approVal.;, If^lijedevifeis;': : fb^dtfyieaanunatiqn.andtKftomrefcthcreqturm . ;!^<V^y^diSii^mufiaii^^ay.certifica(e .of;ag>provalswhich hp5my^^lay^!e^V; dencectf-jthe^u^fyjbfihi^prbduct.;^ . which;:dwly4;distw^sb^ itlieiniand lindica^s^the,' purpose^fbirXw&ch^tb^are. aErH provcdjaiid*theillnii.tatipnsJjUnder whichthey may^fc' used^.:As.(dnaldvtoithe. coiLr ' . siimfr.sthe Bureau-of .Mm^ issues a . list of the devices whichhavemet -; tiipri^uffenieids.-;.... ;;p\ .>; ' /;;-, .t.' :-'' V .*.-The $hhmissipo -of<e<9u^ineht is,, entirely voluntary, on. the part,of- the, manufac-?* turer. On-d^aile^^mpl^ttip tbe tnanpfMu^-dc^ta;; avjfcs; - turned into;ithe';rascwahMti^^e^aptsv6 the treasury offthe>Uhited States;:nphe bf the?money accrues tb-'dfet'Btbreau, of `Mines;;, The approval system^is:;mcitivathd: en| : tirelybythedeiirebf.^ to produce and market?good equipment, the; intest pf the Bto haying safe: equipmerit available commercially, and; the demand o'j^^q^uhKrffor^sudt^v^p^^mit''; ' ( ..Approval schedules have: bn issued for..oxygen breathing apparatus,* chemical ' filter respirators', or gas masks * hose masks" and; mechanical futerrespiratbrs:* .The: l_____________________________--.I:____i -,i___________ 'Jl' -f u___J - zm jo ;.tUB .;i/u0U -vi muK0 nut ^ov oyyivvcw. avuvumw tut..ait'-tjjrvs . ut -. respirators now in common iise. The approval system; undoubtedly is largelyyirespdh- sible for the development of fundamentally safe arid suitable devices, and the damna tion of confusion.in their selection and .use.' v f - . . The .geijebd pian^of the various schedules; is similar. The requirements may be divided into3 parts:- . 4,. . ' i.. : ; ; - i. ' ; (I), Pre-test requirements, or. those'-Vrith which the .manufacturer must comply' . . before examination, and' test of a device, will -be. undertakeri^. For example, /the ` 'respirator must be in a.fully developed form ready forfriarket and available-fbr'pur- - ' ` chase if approval isgiranted. Also, thei^manufacturer must be prepared to test add maintain .control of the essential characteristics Of his device by amethodwhich meets' - * the, approval,of this Bureau.. . v ` . .**/.. j (2) Material, construction, and performance requirements which the equipment must meet by ex^minatioii and test s , (3) : Post-test; requirements,vor those with which the . manufacturer must' comply; . after the. deviceis approved. From the viewpoint of the consumer the most important of these concern; labelirig and marldng, provision of adequate instructions, foriiproptf! - * use of the device, and maintenance ofdesign and qualify of the product marketed under-. ,, the approval.. As mchedCon th^l^tter, the Bureau ofMines obtains samplesofthe- device. on the open market and subjects them to the various inspections and; testa? of . the appropriate schedule. The Bureau reserves the right to withdrew its approval?Of any device'for cause. "; *- ** ' ^ *r v >. ' . . f ,, Interpretation of U. S. Bureau of Mines Approval Schedule 21, Prpcedure^for Testing Filter-Type Dust, Fume, and Mist Respirators for PennissibiUty . -; Among thb reasons for the development of Schedule 21, Procedure for Testihg Filter-Type. Dust,'Fume, :and.!Mist Respirators for. Permissibilifyj Was the realization by the Bureau of. Mines ;and others that there-was a. definite nced for mechanicabfilter. - respirators to protect workers against harmful atmospheric'particulate-matter in situa- ,, . tions where better methods-of control of dust production .and removal were etiier not . available1 or -practical, the inefficiepqr of existing mechanical filter:^respirators, and': , * ^ -*' ' . iQ-`- I' I - . 1 Bureau of Mines, Procedure for.Establishing a Iist:`of Permissible Self-Contained;Oxygen .. Breathing Apparatus; Fees, Character-of Tests, >and^ Condition Under ..'which . Mine..'Rescttie. ; Breathing Apparatus willcbe Tested:-' Scfaed. 13A, Januaty 21, 1930, 12 pp. ` . - * Bureau of-Mines, Procedure for Testing Gas Masks forr-Perinisslbfiity: Sdied. 14D, -May 9, 1935, 17 pp. ' ' . : . ; - \- . 'Bureau of Mines, Procedure for Testing Hose Masks for Permissibility: Sched. ,19, April- - 28, 1927,8,pp.- j ' - ; . .- ' `Bureau of Mines, Procedure for Testing Filter-Type Bust, Fume, and Mist Respirators i . ..for PermissibilitySchet 21, August '-20, 193^, .14 pp,,- " -- ^ .. ! -. " ' /> ' ' O' I '" =. : -O 136 Ttfventy-fourth Annual Safety Congress--National Safety Council a .* equestsfrom manufacturers and consumers that this bureau test and approve such devices. 1 Schedule 21 follows the general plan of the other bureau approval schedules for industrial respirators! theA pre-test and posf-test requirements are quite similar, and the general principles of the test requirements are the same.. The primary purpose of this paper is to explain the reasons for the various test requirements. Pre-Test Requirements' The pre-test requirements of Schedule 21 require that the manufacturer submit : information, drawings,- and samples of the device to be tested. The device must be completely developed and ready for release to the public, and the device , when tested by the manufacturer or his agent must have passed tests of 'the nature described in Schedule 21. The reasons for the third requirement are: (1) To assure the bureau that the manufacturer is prepared to control the filtering characteristics of his respirator; (2) to eliminate any question of competition with private consulting* agencies in developing respirators;' (3) to'fpraish evidence that the respirator really) is ready for release to public market; and (4) to save the manufacturer's and the. Bureau's time. ' After the manufacturer has complied with all the above pre-test requirements he must submit a fee for the examination and test of his device; This fee is turned into the miscellaneous funds of the U. S. treasury and none of die money reverts to the Bureau of Mines. ^ Test Requirements Iq developing die-tests for mechanical filter respirators consideration was given first to the general requirements for a safe and suitable device.' These requirements are similar for all types of industrial respirators. The'respirator must (1) giv.e adequate protection, (2) - be reasonably comfortable and physically convenient to wear, and (3) provide an acceptable service life. Adequate protection implies that the'mechanical filter respirator when properly .. maintained and. worn' must prevent, die wearer from breathing; enough particulate. ' matter to cause a harmful physiological response under the conditions of occupational exposure for which it is designed to be used. _' : Comfort and physical convenience factors are equal in importance ' tb adequate protection. Even though aware of the ultimate serious effect which will be produced after prolonged daily'exposure, workmen are inclined to be diffident and unwitting to suffer much daily inconvenience and discomfort from the respirator. * Encumbrance and discomfort also increase fatigue,-cause distraction, and in general handicap the wearer's ability to take care of himself, thus increasing the - possibility of accident .Important-specific .items include the weight of ;the respirator, its carriage on the face or head, effect on vision, heating of the area of the skin, under the facepiece, inability to expectorate, difficulty in talking^ and resistance to breathing. The importance of comfort and physical convenience cannot be over estimated. , The service life involves elements of practicability in the wearing and maintenance ` of the device, and indirectly the safety. Tins type of respirator is primarily not an emergency device, but a part of the workman's equipment for doing his regular job safely. If the service life is short, the-bother of changing of filter elements will be reflected in the workman's.-attitude toward good maintenance, and use. All mechanical filter respirators ..are subjected to certain inspections and tests and they mt&t fulfill certain requirements. The general design-and* construction, particularly as to facial fit, freedom from irritating facial contacts,'weight, effect on vision and the wearing of goggles, and ease of changing filter elements, and: examined. The materials are examined to determine if they are obviously suited for the purpose for which they are designed. Rubber parts which come in contact - with the >skm must not contain any skin-irritating constituent. Resistance to Air Flow Requirements The requirements for resistance to air flow are the same for ail approved me- . chanical filter respirators.- At no time during or after the filter efficacy- testing period must the resistance to air being drawn through the device at the rate of 85 liters ,n .. `Safety*Equipment 13? .3 (3 cubic; feet) per minute exceed. 50, millimeters (1.97' inches) of water colpinn height .or. the . resistance to air being blown through the device at the .$atne. rate , of flow exceed 25 .millimeters of. water column-Tieight^ An pir flow of . 85 liters per minute is approximately equivalent to the respiratory.rate of a man doing heavy ` work. The ampunt of particulate-matte?, pulled to the: device during the filter efficacy tests is roughly,.qquivalent: to toe amount that wduld be pulled to-the filter, by a worker wearing, the mechanical filter respirator in. a moderately concentrated ^ suspension of the particulate matter during an 8-hour period. Thus resistance to t flow of an approved mechanical filter respirator should hot become excessive when wo 'for ah 8-hour period in most suspensions ofCatmospheric particulate matter-en countered in industry. -The manufacturer is required to give. instructions on cleaning or changing the filter element's when the resistance to air flow noticeably increases. ' 'v . "Direct Leakage and Mari Test - : All.mechanical -filter respirators are subjected to a direct leakage and man.test to determine facial fit, whether, there is any direct leakage-of unfiltered air, and to obtains information on. die comfort of the device. .Three of the mechanical filter respirators-.are worn for 30 minutes by 3 men with different facial features in an .atmosphere containing a heavy suspension of bituminous-coal dust.- At-toe end of the geriodi the respirators are removed and that part of the face covered by thd facepiece is examined for evidence of any leak under the edge of the' facepiece. Sticks millimeter thick were wedged under'the edges" of the facepieces worn by subjects A.and C to cause the leaks. The location and approximate magnitude .of the leaks are shown by the black streaks on that part' of the face covered by the edges of the facepieces. The nasal passages and sputum of the subjects are also examined before and after the tests.? ' Filtering-Efficacy Tests , ! i 'In the development of the filtering-efficacy tests, particular attention was giVen j to.'the physical properties, especially particle size, of toe significant kinds of atmos- pheric particulate matter encountered in industry. Previous studies of filtering materials had shown that; in general, filtering efficacy decreases with a decrease'in . particle size. . '' ' It was decided that most of .the significant industrially, generated atmospheric . particulate matter could bfe classified- into the'`following three groups in' accordance with method of generation, physical state, and .particle size: 1. Mechanically generated dusts resulting from the^ disintegration. of a solid, such'as the dust clouds produced in-the various processes of mining, quarrying and . - tunneling and the grinding, crashing, and general processing of solid materials, i This type of atmospheric particulate matter is referred -to as Type A atmospheric ' particulate matter and mechanical, filter Respirators designed to furnish protection , against.'these suspensions are referred to as Type A..,mechanical filter respirators. 2. Fumes of. various metals (usually .their chemical compounds, as oxides or ; carbonates) such as lead, mercury (except mercury vapor) manganese, -magnesium, aluminum, antimony, arsenic, copper, chromium, iron, cadmium, and zinc -resulting - from sublimation or the condensation of their vapor,-or from.the chemical reactions, between their vapor and gases. This type of atmospheric particulate matter isv re ferred to as) Type B atmospheric particulate matter and mechanical filter, respirators designed to furnish protection against these suspensions are referred to as Type B ' mechanical filter respirators. t 3. Mists as produced by spray-coating with paint and `vitreous-enamels, chromic acid mist as produced in chgomium rplating, and other mists of materials. whose . liquid vehicle does not produce harmful gases or vapors; This type of atmospheric particulate matter is referred to as Type C atmospheric particulate matter and - mechanical filter respirators designed to furnish protection against these suspensions are referred to as Type C mechanical filter respirators. ^ The mechanically'generated dusts and fumes-^consist of solid particler while the' mists consist of liquid or liquid-coated -solid particles. The particleVsize^bf me* chanically generated dusts, extends over a wide range, in some cases,' from particles. - visible to the naked- eye .probably down to molecular dimensions^. -The range in' particle size of fumes is much: smaller. The upper limit is in the lower microscopic . 138 Twenty-fourth Annual Safety Congress--National Safety Council. range (about 0.5 micron), while the lower limit probably `approaches molecular -dimensions. The particles o! some fumes, particularly, zinc and magnesium, readily . ... join ^and form large flocklike clusters. The. effect is least pronounced in the case of lead. Mist particles are spherical and probably more uniform in particle, size than those of dusts and fumes. Suspensions of each of the types: of industrially-generated atmospheric particle matter were selected for use ip4he filtering-efficacy tests. These suspensions were chosen on the basis of their industrial hygienic significance and their physical properties, such as pardde-sice distribution and tendency to aggregate, which have an appreciable effect on filtration. It was desired to test the mechanical filter respirators against the most common or widespread harmful suspensions of each V type; the test suspensions to have: physical properties, such as particle size and aggregation tendency, .which would render them as difficult to remove by filtration as any other suspension of the same type. The test suspensions selected are: (a) For testing Type A mechanical filter respirators or those .designed to' furnish protection against mechanically generated dusts a suspension generated from very fine (99-f- per cent through 325' standard mesh sieve) silica dust consisting of 99+ per cent free silica (SiOi). is used. The suspension is generated in such a-way that all particles larger than about 3 microns, are removed before the suspension . enters die test' chamber. The particle-size distribution of the test suspension -must not exceed a .'geometric .mean of 0.6 micron and'a standard geometric deviation of 1.90. The particle-size determination is made by collecting, samples of the suspension by the Owen^-jet dust counter and determining the particle size distribution by a microprojection method developed by the Bureau of Mines." " (b) For testing Type'B mechanical filter 'respirators or those designed, to furnish protection ^gainst fumes, a lead oxide fume generated by the combustion of 'natural gas containing lead tetraethyl vapor is used. The particles, of this fume, are extremely small and have about the least tendency to . aggregate of any fume, hence , they are very difficult.to remove from the air by mechanical filtration. A suspension, of-magnesium oxide is also used to determine the effect of a fume, whose particles readily aggregate in large clusters, on. the resistance to air flow, of the filter of the device. ''' 1-- (c) For testing Type C^mechanical filter respirators or those designed to furnish protection against mists, three different suspensions are used. '.Chromic acid mist generated by electrolyzing an aqueous solution of chromic acid, as. is done in industrial chromiunrplating; lead paint mist generated by spray-coating.with lead paint; and h water mist carrying silica dust generated by spraying a 2 per cent aqueous suspension of silica dust are used. The water-mist carrying silica dust is used to simulate -the mists generated in-spray-coating with vitreous enamels. 5 . The concentration of the particulate matter in the test suspensions was chosen to represent more .or less the higher concentrations found in industry. Since.-:the concentration of mechanically generated dust found in industry varies over such wide limits it was decided to test Type A mechanical filter respirators against two concentrations; one to represent the more or less average dusty industrial condi tions, and the other to represent very dusty conditions. ~ Hi [fi The complete' mechanical filter respirator is tested on a mechanical testing apparatus. The. test suspension is pulled through the device at the rate of 32 liters (1.13 cubic feet) per minute, continuous flow. , The volume, of air pulled through the mechanical filter''respirator is, 10 cubic meters in all cases except in some, tests against particular-kinds of suspensions as mechanically generated lead -;dusts and in the high-silica dust-concentration test, and the magnesium oxide test whose primary object is to determine 'the increase in resistance, to air flow of the filter with the .amount of particulate matter retained. Ten cubic meter^ is -approximately equivalent' to the volume of air breathed by a worker in 8 hours';-* Th,e samples of particulate .'matter for. concentration determinations are precipitated electrically from .the air- of the test suspension both before and after it lias passed through the mechanical filter respirator. ^ The samples-are collected, in containers which . can be weighed readily.'on ah analytical balance. For reasons of convenience,. speed, - * Brown, C. E. and .Yautf W. P.. The Microprojector for' Determining'. Particle' Size - Distribution and Number .Concentration bf Atmospheric Dusts. XT. S. Bureau of Mines Report \-of Investigations 3289, 1935. ' ' - 'and accuracy the samples. of silica dust are quantitated by weight rather than by . count Samples of the other particulate matter, are quantitated chemically. ' - The -requirements as . to .the amount of particulate-matter that the . mechanical filter respirators must remove from the air pulled-through them is based on the best -* available information on-the concentration of the. particulate matter .-that is safe to V. breathe. Theserequirements are' subject to- change with the1 accumulation of knowl* edge on the'physiological effects of industrially generated atmospheric particulate ." matter. In other words, the filtering-efficacy requirement is that the air inhaled by { ' | the wearer of such a .device must be safe to' breathe, and not that the device have any particular percentage filtering efficiency. t - Mechanical'filter respirators are hot approved for any. substance more harmful than the particulate matter in the test suspension against which they are tested. Thus Type A respirators are hot^approved for any substance more harmful than 'free silica (SiO) dust- However, Schedule 21 provides for testing and,approving mechanical filter respirators against any kind of industrially generated atmospheric .. particulate matter. For example, - Type A mechanical filter respirators are not : . approved for protection against poisoning by breathing dusts whose main 'harmful , constituents are'metals or their compounds. However, two mechanical filter respira tors have been submitted and approved for protection against the inhalation of . % mechanical generated lead' dusts. ' ' Table 1 .summarizes, the details of the filtering-efficacy tests and lists the me chanical filter respirators which have .been approved to date. (Page's 140-141.) . Post-Test Requirements ; 'f. The manufacturer of an. approved mechanical filter respirator is required to . mark his device, with, the name of . his company,-the name letter,-or number by which the type is. designated for trade purposes, and.the approval number assigned to the deyice by the Bureau of Mines-;'and the filter unit must be marked with the approval . number and with the type or kind of atmospheric particulate matter for which it is approve^. ,. * . The mechanical filter respirator and replacement- filter units must be provided With substantial and durable containers.. Copies of the-approval labels issued , td the ^ -. manufacturer by the Bureau of Mines must be attached tp these containers.' The. ~ H"7 approval'label gives the approval number, shows to. whom. the. approval is issued,' . v-;.' states what the device is iand is not approved for, and cautions .the wearer to follow the manufacturer's'instructions for the^qse and >care . of the device, -, The following is a sample of the/reqiiired instructions furnished by .the -manti- facturer. These instructions are similar, for all of thef approved mechanical filter respirators. - t . -* .- - vi -> < Instructions, for Use of Mechanical .Filter Respirator 1. Respirators will not protect Unless .placed on .the face properly each time they are worn. Carelessness in face-fit means dangerous-leakage.1 In general, a better fit is obtained if the .mask is worn not too high on the nose. **... * 2. To fit the respirator tor the face hold the respirator, exhaust valve pointing downward, by the metal screw connection with either hand, and hold the`headstcap with the other, hand Place .the facepiece against the face and hold, it in plaice while pulling the headstrap. over the'head and below the ears. Then adjust'the facepiece until a firm .snug fit is obtained The headstrap- may be adjusted while > 4 -l.-: the respirator, is in place by holding the metal slide between the thumb and forefinger of one hand kfid pulling- oh the. proper strap with the other hand, j 3. To. instruct the wearer/in the proper adjustment of the headstraps ^and ' ^ ' 5 position of the respirator on the face a,cardboard disc is enclosed. To. use "this ,, disc; unscrew the filter r bag,* platfe the. disc against the felt washer in the' metal - connection on. the felt bag, assemble the. respirator, and put it on. The wearer should; " not be;rable to breathe through the respirator- or feel any inward .leakage of air .. under the edges' of the facepiece. r? > * The. presence or absence of dust, stress on the fate inside the line of fit of the 'facepiece after wearing the respirator in a-dusty, atmosphere-can also be used to tell ? >Whetiier'a proper fit`;wss obtained. ' s' `. ' . 4/ The recommended procedure'for cleaning the; filter hag is to insert loosely .. . the nozzle'of.a high-pressure air hose into the bag opening and to blow several 140 Twenty-fourthAnnual Safety Congress--National Safety Council TABLE 1. DETAILS OF FILTERING EFFICACY TESTS AND LIST Kind of i Mechanical' filter-type respirator Industrially generated atmospheric particu late matter against which the device is designed to furnish protection Test suspensions .used Type A Mechanically generated dusts resulting Air-suspended ground flint, which consists principally from the distintegration of a of 99+ percent free'silica (SiO*). Over 99 solid, such as the dust clouds produced in percent of the dust passes through 325- mining, quarrying and tunneling, and the mesh standard sieve ' industrial operations of grinding, crushing, ' and processing of minerals TypeS >. Type C Fumes of various metals (usually their (a) Lead oxide fume-produced by the de- - chemical compounds,-as oxides or carbon- composition and 'combustion of^Iead: ates) such as lead, mercury (except.taer- .tetraethyl - <\ cury vapor), manganese, copper, chromium, ^ iron, cadmium, line, magnesium, alumi num, antimony, and arsenic resulting from sublimation or condensation of their vapor, or from chemical reactions between their vapor and gases . .i - _ Mists as produced by spray-cx>ating with (b) Magnesium oxide fume, freshly pro- * paint and vitreous enamels, chromic acid duccd by burning magnesium ribbon mist as produced in chromium plating.'and (a) Chromic acid mfit produced by electro* other mists of materials whose liquid ve- lyaing an aqueous solution (200-500 htcle does not produce harmful gases or grams of chromic arid per liter) oi vapors % chromic acid Mechanically. generated lead dusts (b) Lead paint mist produced by spraying , a paint having the following composi tion: white-lead (paste having approxi mately .91 percent white' lead and 9 percent linseed, oil hr weight), 100 grams; linseed oil, 50 cubic centime ters; and steam-distilled turpentine, 25 cubic centimeters (c) Mist produced by spraying a 2 percent aqueous suspension of ground flint, air- floated' (994- percent through 325 stand*.' ard mesh sieve). The ground flint con- *sists oi 99+ percent free silica (SiO*). . Mechanically generated dusts whose main harmful constituent is lead, such as lead Mixture used in malting negative plates of lead storage battriries; Contains 72 percent litharge, PbO; 25 percent red lead, PbsO; and 3 percent lampblack ping painted surfaces; paintmaking; pre paring litho-transfers; and mining, milling and processing.lead ores * One milligram = 0.0154 grain. / * One cubic meter = 35.315 cubic feet. Rate of sampling=32 liters (L13 cubic.feet) per minute.. "One milligram of this silica dust contains approximately -300 million, particles as'deter mined by the nupinger method as described by the TJ. S. Public Health Sefvice.' Hence, 1 milligram per euuc meter of this dust is approximately equivalent to 8.5 millions of partiries per cubic foot* * See previous listing oi company for complete address;. : ... a Safety Equipment ' ... i i ' * " ` i;. f , 'v OP APPROVED ^MECHANICAL' FILTER-TYPE RESPIRATORS 141 : Concentration ..Volume of Maximum amount of particulate .. c -, of test test suspension suspension, "i "pulled j *5pas. Name and manufacturer of median* "percobic meter^ of air f* torouga toe s device, cubic meters* Milligrams . c% Milligrams per cubic meter of air to date, September 25, 1954 * `*\ (a) 50. 10 ; 2.88 4 mg; for any 1 of 1.0 Comfo Respirator. Approval < .. 3 devices, or an No. 2101, issued to Mine Safety Ap \n. average .of 3 mg. pliances Co. ' -V I for each of the 3 i* * /TTv" ,- ? i,'1 -- , devices V/v t Willson Bag Respirator Ntw30Q. Approval No. 2102, issued to Will* son Productspluc. * ... ,r.. (b), 5 24^ 9.98 12 mg. for any 1 1.04 Willson 'Bag Respirator No.' 400. of 3 devices, or Approved No. 2103, issued to Will- an average of 19 son Products, Inc.* ' mg; for each of the 3 .' \1 ' 15 Sof lead , \ 9.98 1.5 ' Safety .-Equipment Corp. SBiever - Respirator. Approval' No. .2105, issued to Stanaai:rd' ~Sa*fe'ty Equipment Co. 0.15 Willson Bag Respirator No. .4. Ap? proval No. 2106, -issued to Willson Products, Inc.* - , -.. 100'2S 5 of . icacid 2 9.98 0.1 ' M.S.A. Comfo Respirator. Approval No. 2101. issued to Mine Safety Appliances Co.* n. <: 300-600 of lead .9.98 > 10 4; 5* of : silica dust . i, 9.98 15 5 of-lead 1.5 tt.43 0.15 - M.S.A1 Comfo Respirator not ap proved for -lead containing mists. o . 0.5* "j . is,S.A. Comfo Respirator. Approval No;-2101, issued to Mine;Safety Ap-. pliances Co.*-- ' 0.15 .M.S.A. Comfo Respirator with spe-- - cial filters for lead dust. Approval . , . No. 2107, issued 'to Mine Safety' Ap- plfances Co.* -'X. Willsim Bag Respirator- No. '400b. Approval No. 2108, issued to Willson. Products, Inc;*' ii dr short blasts of air into the bag. This procedure removes frdm.the bag dust and grit which clop the pores of die filter and makes breathing difficult. The proper time for cleaning the. bag is when the wearer experiences. discomfort in breathing. When compressed air is not available some dust may be removed by tapping the bagTT%. . lightly and brushing the outside of the; bag. ' ("V . ' > . 5. Jo prevent irritation of the *ddn and for general sanitary purposes the^^' Mi ' respirator should be "cleaned after each day's use The rubber and metal parts . may Ik cleaned with soap and water, and for general sterilization they may be dipped in a 3 per cent solution'of carbolic acid, a-2 per cent solution of lysol, or a 70 per cent solution of denatured alcohol, then rinsed with water, assembled, and hung up by the loop in die felt bag to dry. The filter bag and headstrap always _.v must be removed before the respirator is washed or sterilized. 6. While not in use the respirator should be kept in a dust-free .place, prefer- ably in die original container. ' The manufacturer is required to maintain the quality of his product and to see that each mechanical filter respirator in all its parts is ^constructed according to the drawings or records that have been accepted by the Bureau for this device and that are in die Bureau's files. Mechanical filter respirators that exhibit changes in de sign or'inefude any parts that have hot been approved are not permissible respirators and must not bear the Bureau's, approval label. Schedule 21 provides for the manu facturer to apply for an extension of approval on any change in the mechanical filter respirator which' does not .affect die filtering .characteristics of the'filter. Changes in the filter require the application for a neW approval. `The Bureau obtains information on the maintenance of design, and quality of approved mechanical. filter respirators by testing samples of the devices obtained on the open market The Bureau reserves the right to rescind for cause any ap- ' proval issued. A Safety Style Show By JE. J. SMITH . Safety and Health Directory-Western Electric Company Hawthorne Works, Q^jy**"* ,... . For the~pdfpo^e of assiStihgour foremen in the selection of the proper safety equipment we have standard specifications and every foreman has a copy. In it he will find the protective*equipment required for anyclass of work. Molders, cupola tenders, furnace tenders and helpers in foundry and- forge are equipped with heaVy duty metal or composition cup goggles with hardened lenses. Tne lenses in die furnace tender's goggles are of a forge and furnace shade. Electric furnace tenders,'however, wear a welder's goggle,'described later. When a goggle is equipped with clear lenses, it is used for such operations as breaking defec tive castings, cleaning castings' with compressed air, grinding castings to remove gates or fins, pounding on castings to remove sand cores, pouring molten metal into molds with hand or bull ladles, removing gates or fins from castings with air chisels, . or hand chisels'and hammers, and working in vicinity of chipping hammers. Leggings are of the non-lacing, non-buckling and snap buttoning type held in . place by hidden steel springs similar, to the old'bicycle pants guard. `They will come off instandy from a tug at any point. There are no gadgets to confuse you or those who are .trying to help you in an emergency. Just one simple thing to remember-- jgrab anywhere and pull. , Men wear safety hats when chipping slag but of cupolas.- Our .construction crews oj^ masons, carpenters, millwrights,- and so on, wear them whenever they are engaged m; work where there is the slightest chance of objects falling from overhead. Our employees wear "Congress" safety.shoes; for their protection In addition to . . die leggings:' v> * -.a We use a leather steel faced glove .when charging a'cupola .or handling pig iron.. Full leather palm gloves with band toil are used in chipping casting fins, load?, ing and unloading ,tumbling barrels,;and removing castings from sand. S For the protection of health, ^workers in the brass foundry' are. provided with ' overalls, and- undershirts with full -length sleeves. This is in accordance with Illinois ` j. D. Safety Equipme(i0 r 143 labor lawn. At the termination of a shift, .molders take shower bafhs bn'company tinier Workers-in this classification,, are provided withtwo lockers, one for working clothes and the other for street clothes. / J?or protection against solid non-volatile particles suspended in air men cleaning ~rsSi;*<vrr^? inside of . a* cupola are provided with respirators. " .. X Incidentally, our supervisors . make periodic inspection of respirators and other 'safety equipment to insure that they have not become worn, damaged, or deteriorated 0` to^such an extent that they no longer provide adequate protection. Special precau^ tions are also taken. tp, see that cracked, broken,'"or pitted lenses ..in goggles are not used, leggings are.not'worn threadbare nor with tom places so as to.permit molten metal to get into the 'upper portion of me shoe and Congress shoe soles are not worn- through^ nor upper, torii outside the'area, covered'by'leggings. Employees operating woodworking machines are required to wear goggles,' when, ' in the opinion-of die..supervisor there, is the slightest eye hazard .present. Goggles are mandatory, oh all tool grinding operations; ,, The hands of all. employees handling rough lumber on machines: such as swing saws# rip saws, ..molders,^ automatic and' glue jointers are protected against cuts, scratches, and slivers with leather-palm canvas gloves. - Those engaged in shellac. dipping operations are supplied with rubber gloves. The fingers of employees gluing wooden parts are protected with finger cots., . .The personal dodung 'of employees dipping parts in shellac or spraying parts is protected with"'overalls.. - > '- In the manufacture of'rubber andiitrother operations our supervisors instruct , employees In the proper manner in whftm-.e<Bupinent is to be .worn to insure the great- . ' est possible-protection. , When mixing rubber compound, sifting or handling sulphur or powdered shellac, cleaning dust collectors^-sacking powdered rubber, breaking rubber scrap,; blowing soapstone and sandblasting rubbers parts, our employees wear heavy duty cup type - goggles. They protect against large, heavy particles, severe impacts and High dust concentrations. = '' When handiing-india-rubber'yello.w.or vermilion, or cleaning brass equipment in . an acid dip tank our*men wear light acid gloves. Gauntlet gloves are worn' when mixing shellac or rubber compounds containing . poisonous substances on milling rolls. They are also used in handling hot molds subsequent to-vulcanizing operations. : The type of respirator, named before, is also worn-when mixing, rubber compound containing,, a high percentage of hard Rubber powder, handling .sulphur, sifting powdered shellac'and in the .performance of other work;, where harmful kinds of dust and material are encountered;- :> , A special, goggle is used to protect against sprayed or .-splashed corrosive solu tions and irritating liquids. - ? l' - ' Undershirts and overalls are also furnished for platers- and acid dippers. Pro tective clothing is laundered weekly.'. Rubber gauntlet gloves are worn by those, engaged in all plating and/dipping operations. , ' . > . - (" - -jj Wooden soledfshoes are. well known in plating circles. The kind we useTTiow- ever, are. equipped with safety toe caps. . i ; Rubber aprons are worn whenever acid is changed or. tanks are cleaned. O' All arc-welding, at Hawthorne js performed inside special enclosures. Welders, helpers, and others "in the^welding, booth are provided with eye and face protection and safety..clothing which, with their persona,!, apparel, affords complete protection from the heat and the rays of the arc.- .Protective goggles are wdm. under the helmet They, protect the eyes against, an unintentional flash which sometimes occurs while men are arranging their .work with ihe helmet^ in the tip or overhead position. v` The arms, hands, body, and feet of welders are protected with such clothing as fanned leather gloveS, .fanned leather.: sleeves, chrome leather aprons, chrome tanned leather leggings, .jumpers; '. : ' v ' i. \ .Periodic inspection is made of fhis equipment too. Special precautions" are taken with- masksto insurethat they donqi leak light,' cover glasses, are not brokeh or cracked, colored^ lenses, afe protected'by' cover glasses,, co^er glasses are",replaced r if burned or pitted so that vision is affected, and fibre is not bruised nor broken. In lathe,.millings, shaping, and similar machine operations our employees wear, the light duty type of goggle. When side protection is required from materials thrown from neighboring machines goggles with side screens are wbrai When acetylene welding or cutting,- a goggle with shade No. 8 is generally used. It is also equipped with a cover glass. *. Although shoes are not furnished by the company,- everya effort is made to encourage employees to wear safety shoes.' -.This shoe is equipped with a safety steel _ toe* cap which will withstand 1,950 pounds before deflecting one-quarter of an inch. -Rough chrome soles,,are worn in our rod mill and other places where! drawing compound^ or oil are encountered. ... Sandblasters wear the same white acid gloves as that worn by platers. Inci-r dentally, we stock and order die right-and left as separate items because the right hand glove wears out much faster. They also wear flame-proof sleeves. On most grinding operations we use a. goggle with screened sides. On lighter operations, where' no side protection is required we use the light duty goggle. All men at Hawthorne working at a height of ten feet or more above the floor are; required to wear life belts. For seven years not one occasion occurred to bring a life belt into play. In the eighth year, however, a 21(hpound apprentice, equipped with a safety beltr and.life line, was working on a scaffold twenty -feet above the ground dismantling a gas holder when one of the hooks failed, . His body dropped a matter of inches when his safety belt `came into play. To prevent callouses'-forming on ^fingers men. who lay out the .lines or form the harness for switchboards wear special gloves. To -facilitate dexterity the glove fingers are- cut off wherever protection is not needed.* ' We use a canton flannel glove for removing hot work from plastic material molds and die casting-machines. Rolling mill operators in our copper rod mill wear puttees for protection against . hot rod stock. The copper sheathing on the inner side is put on by us. It affords additional protection when men-straddle the rod as it comes through the rolls.. -Where men-lift heavy objects such as pig load from one pit to another or load them omto a truck, foot guards are provided. Because of the tripping hazard presented by the foot guards themselves, their use is restricted to operations entailing a minimum of walking. We find coveralls which fit over-ordinary spectacles, quite useful on certain -. jobs where goggles are required less than 50 per cent of the time. However, they. are much too heavy for constant use. In cases where goggles are required more than 50 per cent of the time for operators who wear spectacles in every day life prescription lens goggles. are furnished free of charge. . I want to go bade to the subject of goggles to fell hOw we sold our employees, on goggles. We found 'that mofit of the complaints were relative to discomfort After consulting several optical concerns we found that goggles could-be fitted to give as much comfort as a pair of spectades. So we set up a goggle-fitting Section in'our storeroom and placed in charge an expert who had been trained by one of the optical companies. Our present practice is for the individual to visit the store room himself and have them fitted by this expert Our complaints now are few. We^ran into another snag when, we tried to put goggles on our girls, but here we found that the main objection was appearance. There were some complaints on .. discomfort too. So, in addition to fitting the goggles we designed a different type. . It .was made much lighter in weight and. a forty-two millimetre lens was used with smaller frames. This goggle has a pleasing appearance and has overcome objec tions. This goggle could not be assigned _to our men operators, however, because tire male orbit requires^at^least a fortyrsix millimetre lens for adequate protection. The same safety ^les apply ftb' women as to men, keeping in mind that we do not employ'womeurtin operations entailing contact with acids, oils, or other materials requiring protective clothing.J It is an iron clad'rule, however, that they must wear " goggles on all jobs where there is the slightest eye hazard present Women working around any kind of revolving machinery are required to .wear hair'nets. '- ADJOURNMENT v