Document XE9kKwB6RLLEqgk2B2p9MBew

FILE NAME: Union Carbide (UC) DATE: 1959 DOC#: UC348 DOCUMENT DESCRIPTION: American Standard Safety Code for Head, Eye, and Respiratory Protection Reg. U.S. Pat. Z2.1-T95S Revision <> Z2-I938 UDCSU.89I I American Standard Safety Code for Head, Eye, and Respiratory Protection C T A "4T* f ' y y MAY 141963 Sponsors Department of the Navy National Bureau of Standards U.S. Bureau of Mines -, . r Approved November 27, 1959 AMERICAN STANDARDS ASSOCIATION INCORPORATED American Standard Registered United States Patent Office An American Standard implies a consensus of those substantially concerned with its scope and provisions. The consensus principle extends to the initiation of work under the procedure of the Association, to the method of work to be followed, and to the final approval of the standard. An American Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American Standard does not in any respect pre clude any party who has approved of the standard from manufacturing, selling, or using products, processes, or procedures not conforming to the standard. An American Standard defines a product, process, or procedure with reference to one or more of the following: nomenclature, composition, construction, dimensions, tolerances, safety, operating characteristics, performance, quality, rating, certification, testing, and the service for which designed. American Standards are subject to periodic review. They are reaffirmed or revised to meet changing economic conditions and technological progress. Users of American Standards are cautioned to secure the latest editions. Producers of goods made in conformity with an American Standard are encouraged to state on their own responsibility in advertising, promotion material, or on tags or labels, that the goods are produced in conformity with particular American Standards. The inclusion in such advertising and promotion media, or on tags or labels, of information concerning the characteristics covered by the standard to define its scope is also encouraged. i \ -i A A Published by AMERICAN STANDARDS ASSOCIATION INCORPORATED 10 East 40th Str.eet, New York 16, N> Y. Copyright 1960 by American Standards Association, Incorporated Universal Decimal Classification 614.891/.894 PRINTED IN U.S.A. S1M163/3 | . (Thi f. i was beca ! of :1 : orig j; of S the \ Stan fb- f Proc ; lishe mitte arcs of M the A mate proti be s N. Y Orgai IaJ Amer Amer d b Amen Amer. \H Amerl > I Amer! f^A m ei: \l ilS 1 > ?i ^ f 1 t) 1 : i Ameri Assoc Associ Associ Bause! G ener. Grani' Indusl ith its er the proval sumer, ct pre using to one ranees, nd the ised to ndards ged to labels, elusion erning Foreword ,Thi. . . . . P .1 S...da Safety c * te H -4 &' " * z2-l im > = t u s iz , lhe p" 0^ -- Standards Handbook H2. i_ 1090 {ter revision by a sectional committee organized under Standards .- - P *" , B" ' " , , fished in 1938 as National Bureau of Standards Handbook H24. TM - In 1946 the sectional committee was reconvened and started work o n jta n l mittee on eye protection was organized under the direct Bureau ^esT : tn d T e " c l ^ f r W b L n d e v ^ T ^ e 1938, particularly the use of plastics for eye protection. t a tt,,, ftf this standard will be welcomed. They should Suggestions for improvement game Incorporated 10 East 40th Street, New York 16, be sent to the American Standards Association, Incorporated, v N. Y. The committee that developed this standard is as follows: Dr L eonard Greenburg, Chairman R . L . L loyd, Secretary Organization Represented J AAmiiKeruiwcan. C---e-r-a--m--i-c----S--o-ciet*y. ........ Name and Business Affiliation ...................................... J ohn P aff, RayO-Vac Company j Earl Duncan, P ittsburgh P late Glass Company ( A l t ) American W . - % American Foundrymens Society..................... . . . .F oward C. Baumann, Public Service Electric and Gas American Gas Association............................................................... Company b*4 America. Hy,, l... A - M - ............................... " S r " ' H'` " " " W. E. McCormick, T he B. F . Goodrich Company ( A lt) American Society of Mechanical E ngineers....................................T homas' ^ W alsh, ^ i T American Optical Company _ . r.HARIES W. W yman, W estern Electric Company, Inc American Society of Safety E ngineers.............................................. w j-# Scholtz, Allis-Chalmers M anufacturing . . Company (A lt) , . ....................... F rederick C. Saacke, Air Reduction Company, Inc American W elding Society............. . ................... .......Arthur L. Schmuhl Associated General Contractors of ................... .............M. B. Clayton, Southern Railway System Association of American Railroads. ^ ................... ` ` , william M. Pierce, Employers Liability Assurance Association of Casualty and Surety Companies....................... Corporation, Ltd ,, , , |# , V. 0 . Bohn, The Employers Group ( Al t ) ? _ , ............... Gordon T aylor Bausch and Lomb Optical Company.................................. j g Lueck (A lt) ,, .. . General Services A d m in istra tio n ...... ............... J ohn F. Kirby IV ! EDWARD Meade Granit Cutters' International Association oi A m e n ta ...............`.C arl Dehnehl, Union Carbide Corporation b Industrial M edical Association............................................................. ^ H olland W hitney, American Telephone and Telaernnii ComDanv ( A lt) Organization Represented Name and Business Ailiation Industrial Safety Equipment Association . . . , .D arrell E. Albert, Mine Safety Appliances Company F. R. Davis, Jr, Davis Emergency Equipment Company, Inc C H. Gallaway, American Optical Company S. C. H erbine, Ray-0-Vac Company A. F. P armelee, United States Safety Service Company V. P, Gopcevic, Industrial Safety Equipment Association (Alt) International Association of Governmental Labor Officials.........Morris Kleinfeld, New York State Department of Labor Craic H. H aaren, New Jersey Department of Labor and Industry (Alt) International Association of Machinists............................ . ......... W . G. F u n n W illiam Dameron (A lt) International Brotherhood of Boilermakers, Iron Ship* builders, and Helpers of America................................ .........J ohn V. Kearney M etropolitan Life Insurance Com pany................................ ........J. William F ehnel National Association of Mutual Casualty Companies........ .........E. G. Meiter, Employers Mutuals of Wausau J. C. Stennett (Alt) National Bureau of Standards............................................. .........R alph Stair R. L Lloyd (Alt) E. K. P lyler (Alt) National Electrical Manufacturers Association................. ........H. W. SPEICHER, Westinghouse Electric Corporation National Foundry Association............................................. .........C. T. Sheehan National Safety Council........................................................ .........Karl L. Dunn, Coming Glass Works National Society for the Prevention of Blindness, L. W. H agerup, Lumbermen's Mutual Casualty Company (Alt) .........Leonard Greenburg, Commissioner of Air Pollution of the City of New York Pennsylvania Department of Labor and Industry Telephone Group...................................................... J ames E, O'N eil (Alt) ........ T homas A. Oravecz .........Erle S. Miner, American Telephone and Telegraph Company Charles W. W yman, Western Electric Company, Inc U.S. Bureau of Mines, Department of the Interior.. . . (Alt) .........S. J. P earce U.S. Department of Labor, Bureau of Labor Standards, Lawrence B. Bercer (Alt) ........ Sheldon W. H oman U.S. Department of the Navy......................................... . W illiam G. Griffin ( A lt) ........ H. L. Mathews U.S. Post Office Department........................................... U.S. Public Health Service.............................................. Member-at-Large ............................................................ R. W. W ebster (Alt) . . . . Edward B. Landry , - - - . Donald J. Birmingham - Samuel R enshaw, Ohio State University t c- 1. Put " ' 1.1 t 2 . Ex< i : 3. Del 3.1 i 3.2 ] 4. Get I 5. He, 5 'L s 5. ; 5. t. 5. i 5. i 5. 5. 5. 5. 5.2 5. 5. > ' 5. > 5. . 5. ; 5.3 5. 5. 5. 5. I 5. 5. 5. 6. Ey. 6.1 6. 6. 6. 5. 6. 6. (5.26. I 6. 6. 6. 6. 6.3 6. 6. 6. 6. Company it Company, Company Vsaociation nt oi Labor Labor and ition ition of iph iy, Ine Contents 1. Purpose and Scope ............................................................................................................................... 7 1.1 Purpose ..................................................................... 7 1.2 Scope ............................................................. 7 2. Exceptions .............................................................................................................................................. 7 3. Definitions .............................................................................................................................................. 7 3.1 General Inform ation................................................................................................................ 7 * 3.2 Specific D efinitions.......................................................................................................................... 7 4. General R equirem ents........................... ................................................................................................ 10 , 5. Head P ro tectio n ........................................................................................................................ 10 5.1 Hats .................................................................................................................................................. 10 5.1.1 Types and Classes..................................................................................................................... 10 5.1.2 Materials ................................................................................................................................... 10 5.1.3 General R equirem ents..................................................... 10 5.1.4 Detailed Requirem ents............................................................................................................. 11 5.1.5 Physical Requirements and Methods of T e s t...................................................................... 12 5.1.6 Selection of Head-Protective D evices.................................................................................... 13 5.1.7 Training A id s ........................................................................................................................... 13 5.1.8 Marking ................................................................................................................................... 15 5.2 Helmets and Hand S hields.......................... 15 5.2.1 function ................................................................................................................................... 15 , 5.2.2 T y p e s ................................................................................................................................... 15 ' 5.2.3 S ty le s.......................................................................................................................................... 15 ' 5.2,4 Detailed Requirem ents.............................................................................................................. 15 . 5.2.5 Marking ........................................................................................................................... 17 . 5.3 Face S hields...................................................................................................................................... 17 > 5.3.1 Function .................................................................................................................................... 17 5.3.2 Intended U se s............................................................................................................ 17 5.3.3 Styles and Types ...................................................................................................................... 17 : 5.3.4 Materials .................................................................................................................................... 17 ' 5.3.5 General Requirements .............................................................................................................. 17 5.3.6 Detailed Requirem ents............ : .............................................................................................. 18 5.3.7 Marking ................................................................................................................................... 18 5.3.8 Physical Requirements and Methods of T e s t ...................................................................... 19 6. Eye Protection ....................................................................................................................................... 19 6.1 Styles and Functions ofP rotectors................................................................................................ 19 6.1.1 Goggles, E yecup......................................................................................................................... 19 ,, 6.1.2 Spectacles, Metal or Plastic F ra m e .......................................................................................... 20 f 6.1.3 Goggles, Flexible F ittin g .......................................................................................................... 22 J` 6.1.4 Goggles, Plastic Eyeshield......................................................................................................... . 2 2 6.1.5 Spectacles, Plastic E yeshield.................................................................................................. 22 6.1.6 Goggles, Foundrymen's ........................................................................................................... 22 6.2 Materials and Methods of Test of Protectors................................................................................ 23 6.2.1 Materials ................................................................................................................................... 23 6.2.2 Disinfection ............................................................................................................................. 23 6.2.3 Corrosion R esistance............................................................................................................... 23 6.2.4 Water Absorption ................................................................................................................... 23 6.2.5 Flammability ........................................................................................................................... 23 6.3 L en se s............................................................................................................................................... 23 6.3.1 Types of L enses....................................................................................................................... 23 6.3.2 General Requirements ................................................................................. 24 6.3.3 Detailed Requirements............................................................................................................. 24 6.3.4 Methods of Test and Examination of L enses...................................................................... 24 7. Respiratory Protection ............... 7.1 Classification of Hazards . . . 7.1.1 Oxygen Deficiency........ 7.1.2 Gaseous Contaminants . ., 7.1.3 ~ Particulate Contaminants (Dusts,' Fumai,'Smokes,' Mis'ts F o e s!....................................... E 7.1.4 _ Combination of Gaseous and Particulate Contaminants g .......................................... 28 7.2 Classification of Resopiratorvy Prrnott>etci,r^Di e ^ c e...s." ;'." " "" " "" 10................................................... 28 : Atmosphere-Supplying Respirators ............ .............................................................. 28 7.2.2 Air-Purifying Respirators . . v . . ................................................................ 28 7.3 Requirements for Respirators .......................................................................................... 30 7.4 Selection of R espirators......................... ........ ....................................................................... 33 7.4.1 General Considerations .................................................................. 34 7.5 Use and Maintenance of Respirators.............................................................................................. 34 7.5.11 General C onsiderations..................... . .................................................................. 36 7.5.2 Precautions To Be Taken in the Use of Respirators . ! ...................................................... ^ 7.5.3 Instruction m Use of Respirators. .................................................... 36 7.5.4 Maintaining, Cleaning, Disinfecting, ^ oring Respirators ! ! ! ! ! i ! ! ! : ! i 1! ! ; ' ` ^ Tables a Table 1 Comparative Hat and Cap Sizes .. Table 2 Table 3 Table 4 Color Code for Gas-Mask C anisters............ ................................................... 27 Table 5 Selection of Respiratory Protective Device.......................................................................... 31 Figures ........................................................................ 35 Fig. 1 Fig. 2 Fig. 3 Brinell Hardness Penetrator Assembly.. Dimensions To Be Measured in Heat Deformation pparatus for Heat Deformation Test . . ..................................................... 14 .................................................... 21 Appendix for Section 6 21 A l. Visible-Light Transmiission and Haze Test S 2 AS. Fimog of Goggle, and Spectacle. _ 45 ................................................................................ 45 pfci.. gpvlde nethods lead, fa iguipmei L.2 Sco itions or communi gamma r such as , Variati may be j when it : administr afforded. 3.1 Gem 3.1.1 .'qualificati itrative ag requirente f 3.1.2 ] ("shall" it word "she 3.2 Spec the follow tions, ant according Abrasii L Aerosoi particles it : Air-tin Air-Reg tween the ,an air-line rator wher or hood m Air-Suf blower for h e a p , e y e , and r espir a to r y pr o t e c t io n Z2.1 27 Table 3 Selection of Eye- and Face-Protective Devices Hazard Involved Relatively large flying objects Dust and small flying particles Dust and wind Molten metal Gases, fumes, and smoke Liquids Reflected light or glare Injurious radiant energy (moderate) Injurious radiant energy (intense) Part To Be Protected Eyes, Face Eyes, Face Eyes Eyes, Face Eyes, Face Eyes, Face Eyes Eyes Eyes, Face Permissible Protective Devices Type Reference Goggles Spectacles Face shields 6.1.1, 6.1.4, and 6.1.6 6.1.2, 6.1.5 5.3.3 Goggles Spectacles Face shields 6.1.1, 6.1.4, and 6.1.6 6.1.2, 6.1.5 5.3.3 Goggles Spectacles 6.1.1, 6.1.4 6.1.2, 6.1.5 Goggles Spectacles Face shields 6.1.1, 6.1.4, and 6.1.6 6.1.2, 6.1.5 5.3.3 Goggles 6.1.3, 6.1.4 Goggles Face shields Goggles Spectacles Goggles Helmets Hand shields Face shields Helmets Hand shields 6.1.3, 6.1.4 5.3.3 6.1.4 6.1.2, 6.1.5 6.1.1 All described in 5.2 All described in 5.2.4.2 5.3.3 (must include crown protector and chin protector) All with spectacles described in 6.1.2 All with spectacles described in 6.1.2 7. Respiratory Protection 7.1 Classification of H azards. Hazardous at mospheres fall into the following hroad groupings: Oxygen deficiency Gaseous contaminants: Immediately dangerous to life Not immediately dangerous to life Particulate contaminants (dusts, fumes,mists, fogs) Combination of gaseous and particulate contam inants Immediately dangerous to life Not immediately dangerous to life 7.1.1 O xygen D eficiency. The oxygen content of normal air is about 20.9 percent by volume. Atmospheres in confined spaces such as wells, mines, holds of ships, tanks, and burning buildings may contain a lower percentage of oxygen because of dilution or displacem ent of the air by other gases or vapors, or because of the loss of oxygen by its reaction with, or absorption by, other substances. When the oxygen content of the air is about 16 percent, the flame of a safety lamp will be extin guished. Below this concentration, a person breath ing the air exhibits symptoms ranging from increased volume of breathing and acceleration of pulse rate to unconsciousness and death, depending on the oxygen content of the air and the degree of his physical activity. 7 .1 .2 Gaseous C ontam inants. Gaseous con taminants may be classified into two broad groups as follows: toxic and inert. The toxic or poisonous gases may produce harmful or objectionable response in man in relatively low concentrations, whereas the inert gases produce undesirable effects primarily by displacement of oxygen. The term "gases" as used here applies equally to gaseous substances (such as nitrogen, carbon monoxide, and carbon dioxide) and the vapors of volatile substances (such as benzene and carbon tetrachloride). The toxicity of gases and vapors for m an varies over a wide range. For instance, a 10-minute exposure to a concentration of 120 parts per million (ppm) of phosgene may be fatal, whereas one may safely Z2.1 28 breathe 1,000 ppm of dichlorodifluoro-methane (freon) throughout a working day, 7.1.2.1 Gaseous Contaminants Immediately Dangerous to Life. Gaseous contaminants immediately dangerous to life are gases present in concentrations that would endanger the life of a person breathing them for even a short period of time. For example, 400 to 500 parts of sulfur dioxide per million parts of air (0.04 to 0.05 percent) by volume is considered to be dangerous for a short exposure. 7.1.2.2 Gaseous Contaminants Not Immediately Dangerous to Life. Gaseous contaminants not im mediately dangerous to life are gases present in concentrations that could be breathed for a short period without endangering the life of a person breathing them, but which might produce discomfort and possible injury after a prolonged single exposure or repeated short exposures. For instance, the thresh old limit value for sulfur dioxide has been set at 5 ppm, based primarily on the irritating effect of this gas on the nose, eyes, and throat. 7.1.3 P articulate C ontam inants (D u sts, Fum es, Sm okes, Mists, F ogs). Particulate con taminants may be classified, according to their mode of action, into three broad groups as follows: (1) Toxic particulate contaminants that may pass from the lungs into the blood stream and are carried to the various parts of the body to exert their injurious effects. These effects may be chemical irritation, systemic poisoning, neoplasms (tumors), or such effects as hay fever, asthma, or simple febrile reac tions. (2) Fibrosis-producing dust, such as asbestos and free silica, or other pneumoconiosis-producing dusts that are not taken up by the blood stream but remain in the lungs and may cause significant pul monary impairment. (3) Nontoxic and nonfibrosisproducing particles (so-called nuisance dusts and mists) that may dissolve and pass directly into the blood stream or may remain in the lungs producing neither local nor systemic effects. Particulate contaminants may be classified accord ing to their physical properties into three broad groups as follows: (1) solid, such as dusts and fumes; (2) liquid, such as mists and fogs; and (3) a combination of solid and liquid, such as silicawater sprays and paint sprays. The majority of particulate contaminants are not immediately dangerous to life; that is, days, weeks, or even years of exposure may transpire before harmful effects are noted. Notable exceptions are dusts and mists containing the organic phosphorus insecticides which, if present in high concentrations, \ AMERICAN STANDARD SAFETY CODE FOR may incapacitate or even kill a man in a very short i time. Other exceptions to this generalization are certain radioactive particulates and the toxic war ' smokes such as diphenylchloroarsine (DA) and diphenylaminechloroarsine (DM ). 7.1.4 Com bination o f Gaseous and Parti J culate C ontam inants. In addition to atmospheres containing gaseous or particulate contaminants, there \ are those in which both types occur simultaneously. The contaminants may be entirely different substances, such as carbon monoxide and oxides of nitrogen produced by blasting and the dust from the blasted ij material, or they may be the same substance in the | liquid and in the vapor form, such as slightly volatile <1 liquids that are atomized. The simultaneous occurence a of both gaseous and particulate contaminants in an 1 atmosphere complicates the procedure for providing ij adequate respiratory protection against them. 1 7.2 Classification of Respiratory Protective ; Devices. Respiratory protective devices fall into the following broad groupings on the basis of their mode of functioning: Atmosphere-supplying respirators Self-contained type Hose type Air-purifying respirators Gas masks or chemical cartridge respirators Self-rescue-type respirators Dispersoid (dust, fume, mist) respirators Combination gas and dispersoid respirators , J A more detailed classification, brief description, ; and the limitations of the various types of respir ators follow: 7.2.1 A tm o sp h ere-S u p p lyin g R espirators. Atmosphere-supplying respirators provide a respir able atmosphere to the wearer independent of his immediate atmospheric environment. They may be divided into two main subgroups: self-contained breathing apparatus and hose-type respirators. 7.2.1.1 Self-Contained Breathing Apparatus. A self-contained breathing apparatus is a respirator by means of which the user may obtain respirable air or oxygen from a supply of air, oxygen, or oxygen generating material which is an integral part of the respirator as worn. Self-contained breathing apparatus may be divided into two main subgroups: recirculat ing-type and demand-type. 7.2.1.1.1 Recirculating-Type Self-Contained Breathing Apparatus. Recirculating-type self-con tained breathing apparatus may furnish respirable oxygen to the wearer from either (1) a cylinder of HEAD, EYE, AND RESPIRATORY PROTECTION Z2.1 29 compressed oxygen or (2) a canister containing an oxygen-generating material. 7>2.1.1.3 Lim itations of Self-Contained Breathing Apparatus. The self-contained breathing (1) Compressed Oxygen Type. The mode of apparatus has no limitation as to the concentration functioning of the compressed-oxygen type is as of gas or particulate matter or as to a deficiency of follows: High-pressure oxygen from the cylinder oxygen in the atmosphere in which it is worn. How passes through a pressure-reducing-and-regulating ever, many gases are very irritating to the skin and valve and an admission valve into a breathing bag to mucous membranes when present in high concen from which the wearer inhales through a corrugated trations; and hydrocyanic acid gas can be absorbed breathing tube connected to a mouthpiece or face in dangerous amounts through the unbroken skin. piece through a one-way check valve. The wearer's The wearer has complete freedom of movement, and exhaled breath passes through another check valve may leave the work area through any available exit. and corrugated breathing tube to a container of The length of time that he may remain in the irrespir chemical which removes the exhaled carbon dioxide. able atmosphere is dependent upon the amount of It then passes through a cooler and enters the oxygen or air made available to him by the apparatus breathing bag. In normal use, oxygen enters the and upon his activity. Self-contained breathing ap breathing bag from the supply cylinder only when paratuses are rated according to whether they will the volume of gas in the bag has decreased sufficiently protect for two hours, one hour, three quarters of an to allow a pressure plate to act upon the admission hour, or one-half hour while doing heavy work. If this valve which then admits oxygen until the wearer type of respirator is to be used safely and with exhales. In the event that the pressure-reducing-and- confidence, rather extensive training is required not regulating valve or the admission valve does not function properly, oxygen may be admitted directly only in its care and use but also in an understanding of its limitations. from the oxygen cylinder to the bag through a 7 .2 .I.2 Hose-Type Atmosphere-Supplying Res manually operated by-pass valve. Suitable pressure- pirators. Hose-type atmosphere-supplying respirators release and saliva traps are provided. make air available to the wearer through a hose (2) Self-Generating Type. The mode of connected to a supply of respirable air. They may be functioning of the selfgenerating type is as follows: divided into four main subgroups: (1) hose mask Water vapor in the wearer's exhaled breath reacts with blower, (2) hose mask without blower, (3) air with the granular chemical fill of the canister to line respirator, and (4) abrasive-blasting respirator. liberate oxygen which then enters the breathing bag 7.2.1 .2 .1 Hose Mask with Blower. The hose from which the wearer inhales through a corrugated mask with blower (Type A supplied-air respirator) breathing tube connected to a facepiece. Check valves consists of a full facepiece to which respirable air maintain a unidirectional flow of gases in the closed system. The rate of evolution of oxygen is governed is forced through a large-diameter flexible hose by a hand or motor-operated blower, and through which by the volume rate of breathing of the wearer. the wearer can inhale whether or not the blower is Exhaled carbon dioxide is removed by the canister. operated. Check valves allow air flow only toward A suitable manually operated pressure-relief valve the facepiece. The hose is attached to the wearer's is provided. body by means of a rugged safety harness which has provision for the attachment of a safety line; with this 7.2.1.1.2 D em an d -T y p e S e lf-C o n ta in ehdarness and line the wearer may be drawn to safety Breathing Apparatus. Demand-type self-contained in an emergency. Usually, the hose mask with blower apparatus is designed to supply air or oxygen to the is designed so that two facepiece-harness-and-hose wearer. These gases are not to be used interchange assemblies may be attached to a single, double-outlet ably; that is, oxygen should never be used in an blower. apparatus designed for compressed air, and vice versa. 7 .2 .1 .2 .2 Limitations of Hose Mask With The mode of functioning of the demand-type self- Blower. The hose mask with blower (Type A supplied- contained breathing apparatus is as follows: Oxygen or air is admitted to the facepiece from a cylinder air respirator) has no limitations as to concentration of gas or particulate matter or a deficiency of oxygen of the compressed gas through a two-stage pressurereducing mechanism only when the wearer inhn1*at - and in quantities governed by his breathing. The wearer's exhaled breath escapes to the surrounding atmosphere. in the atmosphere in which it is worn. However, many gases are very irritating to the skin and mucous membranes when present in high concentrations; and hydrocyanic acid gas can be absorbed in dangerous amounts through the unbroken skin. The wearer is 30 limited by the length of the air-supply hose to travel within 150 feet of the blower which must be in respirable air. He must return to fresh air by retrac ing his route in the contaminated atmosphere, other wise the air-supply hose would become entangled. It provides respiratory protection for an unlimited period. 7.2.1 .2 .3 Hose Mask Without Blower. The hose mask without blower (Type B supplied-air res pirator) consists of a full facepiece to which a supply of respirable air may be drawn through a large-diameter flexible hose by the wearer's breath ing effort. Check valves allow air flow only toward the facepiece. The hose is attached to the wearer's body by a suitable harness. The air-inlet end of the hose is provided with a fine-mesh screen to prevent entrance of coarse particulate matter and with a means of anchoring the inlet in respirable air. 7 .2 .1 .2 .4 Limitations of Hose Mask Without Blower. The hose mask without blower (Type B supplied-air respirator) is limited to use in any atmosphere from which the wearer can escape un harmed without the aid of the respirator. The wearer is limited by the length of the air-supply hose to travel within 75 feet of an assured source of respirable air in which the air-inlet end of the hose must be placed. It provides respiratory protection for an unlimited period. 7 .2 .1 .2 .5 Air-Line Respirator. Air-line res pirators (Type C supplied-air respirators) consist of a half-mask facepiece, full facepiece, or a loose-fitting helmet or hood to which respirable air is supplied through a small-diameter hose. They may be divided into two classes: (1) continuous-flow class and (2) demand class. 7 .2 .1 .2 .5 .1 Continuous-Flow Class' Air Line Respirator. Continuous-flow class air-line res pirators (Type C and CE supplied-air respirators) supply a continuous flow of respirable air to the facepiece, helmet, or hood through a small-diameter hose. The wearer's exhaled air and the excess air entering the facepiece, helmet, or hood covering escapes to the surrounding atmosphere. Provision is made for attaching the air-supply hose to the wearer and for detaching the air-supply hose rapidly in an emergency. The respirator is designed to allow at least 4 cubic feet of air per minute to enter the facepiece and at least 6 cubic feet of air per minute to enter the helmet or hood. 7 .2 .1 .2 .5 .2 Abrasive-Blasting Respirator. The principle of operation of the abrasive-blasting respirator (Type CE supplied-air respirator) is the AMERICAN STANDARD SAFETY CODE FOR same as that of the continuous-flow class air-line ; respirator. However, it is constructed so that it will : protect the head and the neck of the wearer and the eyepiece of the respirator from the rebounding ; abrasive. The respirator is designed to allow at least i 4 cubic feet of air per minute to enter the facepiece and at least 6 cubic feet of air per minute to enter the helmet or hood. Only a full facepiece or hood and helmet is used with this respirator. 7.2.1.2.5.3 Demand-Class Air-Line Res pirator. Demand-class air-line respirators (Type C supplied-air respirators) supply respirable air to the facepiece only when the wearer inhales, and at a ......... rate governed by his volume rate of breathing, A source of respirable air, either an air compressor or a container of compressed air, is attached by a small- diameter hose to a demand valve which is actuated by a slight negative pressure created when the wearer inhales. Upon actuation, it allows air to flow to the facepiece through a flexible corrugated breathing tube. Upon exhalation, the demand valve closes and permits no air to flow to the respirator. The exhaled breath escapes to the surrounding atmosphere through an exhalation valve or valves. The demand valve is attached to the wearer ao as to allow the air-supply line to be dragged behind the wearer without exerting * a pull on the facepiece. Provision is made for detach- : ing the air-supply hose rapidly in an emergency, . Helmets or hoods are not used with this respirator. \ 7 .2 .1 .2 .6 Limitations of Air-Line Respira- , tors. The air-line respirator (Type C supplied-air i respirator) and the abrasive-blasting respirator (Type CE supplied-air respirator) are limited to use in 1 concentrations of gases or vapors that are not im- ; mediately harmful or from which the wearer can i escape unharmed without the aid of the respirator. They are not to be worn in an oxygen-deficient atmosphere. The wearer's travel is limited by the length of the air-supply hose, and he must retrace his route in the contaminated atmosphere to return to fresh air while wearing the respirator. These ` respirators shall be used within the limits set by the manufacturer for air-supply hose length and range of air pressure applied to the inlet of the air-supply hose. They provide respiratory protection for an unlimited period. 7.2.2 A ir-P urifying Respirators. Air-purifying respirators remove gaseous or particulate contamin ants, or both, from otherwise respirable air th a t is inhaled by the wearer. They may be divided into three classes: ( 1 ) c h e m ic a l-filte r ty p e , (2 ) m ec h an ical-filter type, and (3) combination chemical- and mechanical-filter type. it .iK ",, n u L l. , I .tw !. i>. f \ &iir` !> *=i--'';*; ; 'v Z2.1 HEAD, EYE, AND RESPIRATORY PROTECTION 31 7.2,2.1 Chemical-Filter Respirators. Chemical- organic vapors, or a combination of two or more filter respirators such as gas masks, chemical-cartridge classes of gases or vapors such as acid gases and respirators (non-emergency gas respirators), and self organic vapors or all gases and vapors. The canisters rescue-type respirators remove toxic gases and vapors of many types of gas masks are manufactured in from inspired air by sorption, chemical reaction, or two sizes, namely, regular or "industrial size," and oxidation by the granular fill of the canister or the large or "supersize" canisters. Everthing else cartridge. The exhaled breath escapes to the surround being equal, the large canister provides a longer ing atmosphere. service time than the regular size between changes of 7.2.2.1.1 Gas Masks. Gas masks consist canister, containing the appropriate granular fill, a full facepiece, and a body harness to hold the canister securely in place on the body of the wearer. The inspired air is drawn through the canister and enters the facepiece in such a manner as to inhibit the accumulation of moisture on the eyepieces. A check valve prevents exhaled breath from entering the canister and allows it to be forced out through an exhalation valve in the facepiece to the surround- [ ing atmosphere. The facepiece is held securely to the wearer's face by an elastic head harness. Universal gas masks have an indicator or timer which shows [ when the canister should be changed for protection I against carbon monoxide. ' canisters, but the limitations of both in regard to ofmaaximum concentration of gas against which they will protect are the same. In most cases, a canister designed for a single gas or a single class of gases and vapors will afford respiratory protection for a considerably longer period than will a canister of the same size designed for protection against a multiplicity of gases and vapors. Gas-mask canisters manufactured in the United States of America are marked in bold letters with the name of the atmospheric contaminants for which the canister is intended or with the words "UNI VERSAL GAS-MASK CANISTER" in capitals, as well as being given a distinctive color in accordance with the American Standard Safety Code for Iden tification of Gas-Mask Canisters, K13.1-1950. These E Gas masks are designed to provide respiratory colors serve as an aid to rapid identification of I protection against a single specific gas such as canisters. The table from 6.1 of the above code is I chlorine, a single class of gases or vapors such as reproduced here for ready reference (see Table 4). Table 4 Color Code for Gas-Mask Canisters Canister, Type Letter Atmospheric Contaminants To Be Protected Against Color Assigned1 A A A ' B C k D ;; AE, etc 1 AB 1 - ABC IfN Acid gases Hydrocyanic acid gas Chlorine gas Organic vapors Ammonia gas Carbon monoxide Dust, fumes, mists, fogs, and smokes in combination with any of the above gases or vapors Acid gases and organic vapors Acid gases, organic vapors, and ammonia gas All of the above atmospheric contaminants White2 White with %-inch green stripe around the canister near the botton W hite with V6-inch yellow stripe around the canister near the bottom Black2 Green Blue %-inch contrasting black or white stripe around the canister near the top Yellow Brown Red. Filters are included in this canister, but stripes to in d ic a te th e m are u nnecessary. fe, Note 1: Gray shall not be assigned as the color for any gas-mask canister. L Note 2: Canisters for a single gas or vapor other than am m onia o r carbon monoxide shall have a Vi-inch colored stripe around Kihe canister near the bottom. Z2.1 32 7.2.2.1.2 Limitations of Gas Masks. The gas mask is limited to use in atmospheres containing at least 16 percent of oxygen and not more than 2 percent of most toxic gases (3 percent of ammonia). Many gases are very irritating to the skin and to the mucous membranes when present in these maximum concentrations; and hydrocyanic acid gas can be absorbed in dangerous amounts through the unbroken skin, its effects depending mainly upon the concentration of the gas and the duration of the exposure. The wearer has complete freedom of movement. A gas mask provides respiratory protec tion for a period that depends on the type of canister, the concentration of the gas, and the activity of the wearer. A gas mask with canister for protection against carbon monoxide should have an indicator to show when the canister is to be replaced. No practicable method is available to warn the wearer of leakage of relatively odorless gases through the canister. It is important that the proper gas-mask canister be used for the intended purpose. For instance, an ammonia gas-mask canister will not afford respiratory protection against acid gases, organic vapors, or carbon monoxide. 7.2.2.1.3 Chem ical-Cartridge Respirators. Chemical-cartridge respirators (non-emergency gas respirators) consist of a half-mask facepiece to which is attached one or two cartridges. Like canisters, the cartridges are filled with granular materials that remove gases or vapors from the air drawn through them. Check valves prevent exhaled breath from entering the cartridges and allow it to be forced out through an exhalation valve in the facepiece to the surrounding atmosphere. The facepiece is held secure ly to the wearer's face by elastic headbands. The cartridges are usually designed to provide respiratory protection against single gases or vapors or against single classes of gases and vapors. They are easily removed and replaced. 7 .2 .2 .1 .4 Limitations of Chemical-Cartridge Respirators. The chemical-cartridge respirator (non emergency gas respirator) is limited to use in atmospheres that are not immediately dangerous to life; hence, it shall not be worn in an atmosphere deficient in oxygen. The wearer has complete freedom of movement. A chemical-cartridge respirator provides respiratory protection for a period that depends on the type of cartridge used, the concentration of the gas or vapor, and the wearer's activity. Its use is limited to low concentrations of certain gases and vapors such as a maximum of 0.1 percent (1,000 ppm) of organic vapors. It should not be used for AMERICAN STANDARD SAFETY CODE FOR protection against (1) harmful gases or vapors that cannot be detected by the sense of smell; (2) gases or vapors that are highly toxic in low concentration, 1 such as phosgene and arsine; or (3) concentrations i of gases and vapors that are highly irritating to the eyes. It is important that the proper chemical cartridge be used for the intended purpose; for instance, an organic vapor cartridge will not afford respiratory protection against ammonia. Knitted cotton covers for the face-contacting surface of the facepiece should not be used since they are not gastight. 7.2.2.1.5 Self-Rescue-Type Respirators. The self-rescue-type respirator is designed to provide the greatest possible respiratory protection consistent with the practicability of carrying the device at all times so that it is always available for use during escape in the event of a catastrophe. It consists essentially of a small filter element, a mouthpiece, a nose clip, and a means of carrying the device conveniently on the body or storing it near the work location. Most filter elements are similar to chemical cartridges made for protection against specific gases or vapors, but particulate filters are also available. One self-rescue-type respirator offers protection against carbon monoxide present in the atmosphere following an explosion or fire in a mine. The filter cartridge for this type shall be protected from moisture to keep the chemical fill active. ; / i: : 1: :5 F '' s i d * U 1 p ' r 7 .2 .2 .1 .6 Limitations of Self-Rescue-Type ; h i Respirators. Self-rescue-type respirators should never ti be used as a working tool, but only as a means dur ing escape from a contaminated area to enhance the ! si possibility of reaching a safe atmosphere or a more ; b positive type of respiratory protective equipment. The magnitude of protection afforded usually falls be i g tween that provided by gas masks and by chemical- : ir cartridge respirators. For example, the self-rescue- rr. type respirator for protection against carbon monox : ti ide will provide at least 30 minutes service in an ta atmosphere containing 1 percent by volume of carbon c< monoxide. th 7.2.2.2 Mechanical-Filter Respirators. Mechan m ical-filter respirators such as dust, fume, or mist Tl respirators remove particulate matter from the th inspired air by capture on the filter, which is usually ce a fibrous pad. These respirators consist of a full re or half-mask facepiece to which are attached one of or two filters through which the inspired air is drawn. Check valves, present in most mechanical- Fi filter respirators, prevent exhaled breath from passing ] ch through the filters and allow it to be forced out va through an exhalation valve in the facepiece to the So ( head, eye, and respiratory protection Z2.1 33 <Hr& ra'Xto-rt... prong COE :WC use,; uthpie the dene r the w on o chemic cific ga available^ protection \ itmosphere; The 4ed irony scue-Typ<i mid never! leans dur ihance the" or a m ore1! ment. The.' falls he-* chemical-1' elf-rescuen mono*, ice in an of carbon . Meehan , or mist from the is usually of a full ched one id air is ichanicalm passing irced out ce to the unrounding atmosphere. The facepiece is held se provide respiratory protection against particulate curely to the wearer's face by elastic headbands. matter, in addition to the respiratory protection Knitted cotton covers are sometimes used to cover against gases and vapors furnished by their granular the face-contacting surface of the facepiece to absorb fill. Some chemical-cartridge respirators contain perspiration and to prevent irritation of the skin filters for the same purpose. Others have filters when the respirator is worn in hot places or in air attached so that the filters may be changed one or containing certain irritating dusts such as lime. more times before the cartridges are changed. The Mechanical-filter respirators are designed to provide type of protection afforded by the filters in gas-mask respiratory protection against a single specific dust, canisters and chemical-cartridge-respirator cartridges fume, or mist, a single class such as toxic dusts, or is stated on their labels. } combination of several classes of particulate matter 7.2.2.5 Limitations of Combination Chemical- such as dusts, fumes, and mists. and-Mechanical-Filter Respirators. The limitations of The filters may be of the single-use or re-usable combination chemical-and-mechanical-filter respira type. Single-use filters cannot be cleaned and re-used, tors generally are the same as for each type of but should be discarded after they have served their respirator given in the preceding sections. However, purpose. Re-usable filters, cleaned mechanically ac the limitation of dust filters in regard to protection cording to the manufacturer's instructions, may be against gases and vapors given in 7.2.2.3 obviously re-used. They should never be washed or treated with is modified by the type of protection afforded by solvents. the chemical-filter respirator (gas-mask or chemical- 7.2.2.3 Limitations of Mechanical-Filter Res cartridge respirator) against gases and vapors. pirators. There is a practical limit for the concentra tions in which a mechanical-filter respirator should be used. This is determined by the time required to 7.3 R equirem ents fo r R espirators. Respirators of all types should be capable of providing an plug the filter. For example, if the concentration is adequate degree of respiratory protection against so high that the filter must be changed several times given atmospheric contaminants when the proper an hour in order that the wearer can inhale without type has been chosen and when it is maintained and undue resistance, a more suitable type of respiratory used correctly. Specific requirements for most of the protective device should be selected. Mechanical-filter types of respirators used in industry in the United respirators should not be used in sand- or shot States of America have been set up by the Federal blasting operations in which one might be exposed to heavy concentrations of particulate matter and to rapidly rebounding particles of the abrasive. For Bureau of Mines. These requirements are published as Bureau of Mines Schedules, a list of which fol lows:2 such conditions, the abrasive-blasting respirator shall Bureau of Mines, Procedure for Establishing a be used. List of Permissible Self-Contained Mine Rescue Mechanical-filter respirators do not protect against Breathing Apparatus; Fees, Character of Tests, and gases and vapors or against an atmosphere deficient Conditions Under Which Mine Rescue Breathing in oxygen. The wearer has complete freedom of Apparatus Will Be Tested: Schedule 13, March 5, movement. The useful life of the filters is limited by 1919, 13 pp; Schedule 13A (revision of Schedule the build-up of resistance to inhalation as the con 13), January 21, 1930, 12 pp; Schedule 13B (re taminant is removed by the filter. The higher the vision of Schedule 13A), August 12, 1935, 12 pp; concentration of contaminant in the air drawn into Schedule 13C (revision of Schedule 13B), July 9, the filter and the greater the wearer's activity, the 1946, 11 pp; Schedule 13D (revision of Schedule more rapidly the resistance to inhalation increases. 13C), September 22, 1956, 12 pp. (Code of Federal This applies particularly to dusts and fumes. Hence, Regulations reference: 30 CFR Part 11.) the use of dust and fume respirators in high con Bureau of Mines, Procedure for Establishing a 8 centrations of these contaminants requires frequent List of Permissible Gas Masks; Fees, Character of replacement of disposable filters or frequent cleaning Tests, and Conditions Under Which Gas Masks Will of re-usable filters. Be Tested: Schedule 14, May 22, 1919, 13 pp; 7.2.2.4 Combination Chemical-and-Mechanical- Supplement to Schedule 14, January 6, 1920, 4 pp; Filter Respirators. Combination chemical-and-mechanical-filter respirators remove toxic gases and vapors and particulate matter from inspired air. Some gas-mask canisters contain special filters which 2 Copies of the most recent Bureau of Mines Schedules and List of Respiratory Protective Devices Approved by the Bureau of Mines may be obtained from the Publications Distribution Section, Bureau of Mines, 4800 Forbes Street, Pittsburgh 13, Pennsylvania. Z2.1 3 4 AMERICAN STANDARD SAFETY CODE FOR E Schedule 14A (revision of Schedule 14), August 25, comfortable and convenient to wear; and (3) It j 1923, 15 pp; Schedule 14B (revision of Schedule must be constructed of durable materials. If no \ 14A), August7 ,1 9 3 0 ,1 3 pp; Schedule 14C (revision Bureau of Mines schedule applies to a respirator ; of Schedule 14B), August 20, 1934,17 pp; Schedule being considered for use, it should be examined to j 14D (revision of Schedule 14C), May 9,1935,17 pp; see that it fulfills these three requirements. Further Schedule 14E (revision of Schedule 14D), December judgment might be based on its compliance with the , 24,1941,19 pp; Schedule 14F (revision of Schedule performance requirements of the most closely related ; 14E), April 23, 1955. (Code of Federal Regulations respirator approved by the Bureau of Mines. reference: 30 CFR Part 13.) ' Bureau of Mines, Procedure for Testing Hose Masks for Permissibility: Schedule 19, April 28, 1927, 8 pp; Supplement to Schedule 19, August 20, 1934, 3 pp. Procedure for Testing Supplied-Air Respirators for Permissibility: Schedule 19A (re vision of Schedule 19 and supplement, enlarged to include special hose masks without blowers, air-line respirators, and abrasive-blasting helmets, hoods, or masks), August 9, 1937, 21 pp; Schedule 19A as amended in the Federal Register on March 13, 1948, to include Type C, demand-class supplied-air res pirators; Schedule 19B (revision of Schedule 19A), 7.4 Selection of R espirators 7.4.1 G eneral C onsiderations. In choosing a respirator to be used for respiratory protection in any given situation, the following factors should be considered: (1) the nature of the hazard; (2) the severity of the hazard; (3) the type of con taminant; (4) the concentration of the contaminant; (5) the period for which respiratory protection must be afforded; (6) the location of the contaminated area with respect to a source of respirable air; (7) the expected activity of the wearer; and (8) the operating characteristics and limitations of the avail April 19, 1955. (Code of Federal Regulations refer able respirators. ence: 30 CFR Part 12.) Table 5 lists the hazards and the respirators that Bureau of Mines, Procedure for Testing Filter-Type are designed specifically to afford respiratory protec Dust, Fume, and Mist Respirators for Permissibility: Schedule 21, August 20, 1934, 14 pp; Schedule 21A (revision of Schedule 21), April 19, 1955. (Code tbiyoncoangsaiidnesrtintghemth.e Bfoyrergeofeinregncfeacttoorst,hitshetaubslee,r acnadn i b: determine the type of respirator that should be ; ir of Federal Regulations reference: 30 CFR Part 14.) used. The self-contained breathing apparatus and the Bureau of Mines, Procedure for Testing Non hose mask with blower would give respiratory protec tl emergency Gas Respirators (Chemical Cartridge Res tion against any of the hazards listed, but these it, pirators) for Permissibility: Schedule 23, November devices are not included in the list of respirators 01 13,1944,10 pp; Schedule 23A (revision of Schedule that could be used in the less hazardous situations is 23), April 23, 1955. (Code of Federal Regulations because their use would amount to "over-engineer .a m reference: 30 CFR Part 14A.) ing." ir si Each respirator that has been approved by the Even though most of the factors in 7.4.1 are ! b< Bureau of Mines has met the requirements of the interrelated, a brief discussion of each follows: i st pertinent schedule that was in effect at the time 7.4.1.1 Nature of the Hazard. The user should to of the approval. In general, each revision of a determine whether or not the atmosphere is deficient as Bureau of Mines schedule makes these requirements in oxygen, and whether the contaminant is gaseous oi more severe. A Bureau of Mines approval on a or particulate, or a combination of the two. ac ruensdpeirrawtohrircehmiatinwsasinaepfpfercotveedvenhatshobuegehn trheevisscehdedounlee deter7m.i4n.e1.2whSeethveerritoyrofntohte Hthaezaradtm. Toshpehuesreer sishouimld ty or more times since then. Hence, if the user wishes mediately dangerous to life. This is discussed under to check on the minimum performance that he may Classification of Hazards in 7.1. cc expect from the respirator, he should consult the 7 .4 .1 .3 Type of Contaminant ce schedule or revision thereof, which is shown in the is list of schedules as being in effect when the approval 7.4.1.3.1 Gaseous Contaminant. Where the 2 was granted. contaminant is gaseous, the user should determine n< The Bureau of Mines performance requirements whether it is an acid gas, an organic vapor, ammonia, 0. for a respirator are based on its field of use and carbon monoxide, or a mixture of two or more of ai upon three fundam ental requirem ents for a satisfac these gaseous contam inants. T h is inform ation is at tory device: (1) It must provide adequate protection essential to the choice of the proper gas mask or for a satisfactory period; (2) It must be reasonably chemical-cartridge respirator because the different th 12.1 CODE TOR l HEAD, EYE, AND RESPIRATORY PROTECTION 35 id (3) I t L ils. If no:/J respirator.' am in ed .to .$ | s. Further yg e with the f ely related ines. . hoosing a Section in >rs should 'Hfl tzard; (2) >e of con* ntaminant;.:; ction must, , ntammated.^ e air; (7) d (8) the the avail* Table 5 Selection of Respiratory Protective Device Hazard Respirator Oxygen deficiency Self-contained v>reathing apparatus Hose mask witb blower Gaseous contaminant Immediately dangerous to life Self-contained breathing apparatus Hose mask with blower Gas mask Not immediately dangerous to life Air-line respirator Hose mask without blower Chemical-cartridge respirator Particulate contaminant Dust, mist, or fume respirator Air-line respirator Abrasive-blasting respirator Combination gaseous and particulated contaminant Self-contained breathing apparatus Immediately dangerous to life Hose mask with blower Gas mask with special filter Not immediately dangerous to life Air-line respirator Hose mask without blower Chemical-cartridge respirator with special filter ' ` '^ 1 rators that *,w4 ory protec* table, and e user can should be i l tus and the ^ :ory protec* but these. ;| | respirators 3 situations er-engineer*^ types of gases require different absorbents or com binations of absorbents to remove them from the inspired air. 7.4 .1 .3 .2 Particulate Contaminant. Where the contaminant is particulate, the user should know its physical form; that is, whether it is a dust, fume, or mist. Furthermore, he should know whether it is a toxic type (containing, for instance, arsenic, anti mony, cadmium, or lead), a pneumoconiosis-produc ing type (containing, for instance, asbestos or free i 7.4.1 are Hows: user should is deficient t is gaseous` o. ' silica), or a type having a low order of toxicity and being nonfibrosis producing (containing, for in stance, flour or wood). This information is essential to the choice of the proper dispersoid respirator, as a respirator designed to protect against one type of particulate matter does not necessarily, afford adequate protection or service life against the other user should ' types. here is im- " 7.4 .1 .4 Concentration of Contaminant ussed under 7.4.1 .4 .1 Gaseous Contaminant. Where the contaminant is gaseous, the maximum expected con centration of the gas should be known. Where this Where the d determine > >r, ammonia, or more of ; ormation is ;as mask or the different is above 3 percent by volume of ammonia gas, or 2 percent by volume of other gases, a gas mask is not adequate and should not be used. If it is above 0.1 percent by volume (1,000 ppm) of organic vapors, an organic-vapor chemical-cartridge respirator is not adequate and should not be used. 7 .4 .1 .4 .2 Particulate Contaminant. Where the contaminant is particulate, the proper type of dispersoid respirator may give an adequate degree of protection, yet its service life may be too short to be practicable or economical. That is, the filter may plug too readily with a rapid increase in the inhalation resistance, thus necessitating frequent changing or cleaning of the filter material. Where practicable, an air-line respirator should be used in high concentrations of particulate matter. 7.4.1.5 Period of Required Respiratory Protec tion. The period of respiratory protection required has considerable bearing on the decision about which type of respirator to use in any given situation. The self-contained breathing apparatus, the gas mask, and the chemical-cartridge respirator provide respira tory protection for a limited period, whereas the hose mask with blower, the air-line respirator, and the abrasive-blasting respirator do so for an unlimited period; thus, for protracted periods of use, the latter types offer some advantages. 7 .4 .1 .6 Location of Contaminated Area with Respect to Source of Respirable Air. This is a factor that is frequently overlooked when choosing a respira tor. In using a hose mask, air-line respirator, or abrasive-blasting respirator, the distance that the wearer can go into a contaminated atmosphere is limited by the length of the hose connected to the source of respirable air. Furthermore, the presence of the hose requires that be enter and leave the area by the same route. When wearing a self-contained breath ing apparatus or a gas mask, a person may leave the Z2.1 *1 36 ' AMERICAN STANDARD SAFETY CODE FOR contaminated area by another exit, but he should make certain that the device will afford protection 7,5.2 Precautions To Be Taken in the Use of Respirators for a period adequate for him to reach fresh air, taking into account possible delays. For instance, in mine-rescue work, the maximum distance from fresh air that a crew wearing 2-hour self-contained breathing apparatus should cover is 1,000 feet (2,000 feet round trip) under ideal conditions. This distance is decreased to not more than 50 feet from fresh air if the crew has to crawl in a low passage. 7.4.1.7 Activity of the Wearer. In many stances, the respirator that would be first choice from the standpoint of respiratory protection or period of protection cannot be used because it would limit the activity of the wearer. For instance, a hose mask 7.5.2.1 Precautions To Be Taken in the Use of a Self-Contained Breathing Apparatus 1 (1) The wearer of a self-contained breathing apparatus should be physically sound and fit and should be thoroughly trained in the construction, testing, use, care, and limitations of the apparatus before he attempts to wear such apparatus in a hazardous situation. in (2) Make certain that the self-contained breathing apparatus is in good operating condition. (3) Make certain that the apparatus is capable : of supplying air or oxygen for the period that the wearer must remain in the contaminated area. } would not be practicable for use where the wearer has to weave in and out of a series of obstructions such as pipes because of the difficulty of pulling the heavy hose after him and his inability to escape quickly to fresh air in event of danger. An air-line (4) Adjust the apparatus to the wearer and i test for tightness according to the manufacturer's instructions. : (5) If the wearer is to enter a confined space j containing an atmosphere that is extremely hazardous, ] respirator would likewise be rather impracticable connect a strong life line to his body. This will serve - for use where the wearer must be moving about (a) as a means of guiding him to the exit; (b) as ' constantly in the contaminated area, or going from a means of transmitting prearranged signals between one room to another, because of the inconvenience him and the men at the fresh-air base; and (c) as , and tripping hazard of the air-supply hose. a means of aiding in rescue operations in case of an i The activity of the wearer has a marked effect on accident or emergency. This life line should be held the life to be expected from a self-contained breath ing apparatus, gas mask, chemical-cartridge respira tor, or dispersoid respirator. The volume of air breathed by a man walking at a rate of 4 miles per hour is more than three times that breathed when he is standing still. Hence, the supply of oxygen in a self-contained breathing apparatus is used up faster, the absorbent capacity of a gas-mask canister or a chemical cartridge is exhausted faster, and the by two attendants, at least one of whom is wearing | a similar apparatus. ^ (6) Enter the contaminated area cautiously, ! and, if the contaminant is detected by odor, taste, or , eye, nose, or throat irritation, return to fresh air immediately and ascertain the cause. 1 (7) Bear in mind the time limitations of the apparatus and allow an adequate margin of time : for the return to fresh air. filter of a dispersoid respirator would be plugged (8) The mouthpiece and nose clip, or the 1 faster while the wearer is exercising than when he facepiece, should not be removed until the wearer is at rest. is certain that he is in respirable air. 7.4.1.8 Operating Characteristics and Limita tions of the Available Respirators. The operating 7.5.2.2 Precautions To Be Taken in the Use of characteristics and limitations of respirators have a Gas Mask been discussed in 7.2. . (1) Make certain that the gas mask is in 7.5 Use and M aintenance of R espirators good operating condition. 7.5.1 General Considerations. Respirators are (2) Adjust the canister harness on the body used to supplement other methods of control of air so that, when the facepiece is put on, there is some borne contaminants rather than to substitute for slack in the breathing tube when the wearer's head them. Every effort should be made to prevent the is in the normal position. dissem ination of contam inants into the breathing (3) A djust the facepiece to m ake a gastighl zones of the workers. In some instances, it is necessary fit on the wearer's face. There are two means of to use respirators only until these control measures testing a facepiece for a gastight fit: (a) Close off the have been taken; in others, such measures are im exhalation valve and exhale gently into the facepiece. practicable, and the continued use of respirators is If a slight positive pressure can be built up in the face necessary. piece without any indication of outward leakage of Z2.1 HEAD, EYE, AND RESPIRATORY PROTECTION 37 W "t* the Use o j air between the facepiece and the face, it is adjusted properly, (b) Close off the breathing tube, inhale so (3) Connect the proper length of hose (not over 150 feet) to the blower and to the facepiece, i'-T'S/Sj i 't t e W jjjl that the facepiece starts to collapse, and hold the breath for about ten seconds. If the facepiece stays making sure that all gaskets are in place and that the connections are tight. Where more than one d breatHngl md fitandl onstruction/j in its partially collapsed condition and no inward leakage of air is detected, it is adjusted properly. (4) Test the complete gas mask for gastightness by closing off the air-intake at the bottom hose line is to be used, each should originate at the blower. (4) Before entering a confined space such as a tank or sewer containing an atmosphere that is e apparatus! of the canister, either with the palm of the hand extremely hazardous, connect a strong life line to tratU8 -m i/M or with the bottom canister seal, and inhaling as in the D-ring of the body harness. This life line should Ifcontained (3) (b) above. This test checks the gastightness of the canister be held by two attendants so that the wearer can be removed from the contaminated atmosphere in l condition.'g| or timer gaskets and of the connection between the case of accident or emergency. is is capable $ breathing tube and the canister or timer, (5) Operate the blower for a minute or two od that thej (5) Make certain that the contaminated at at a rapid rate to blow any dust out of the hose and area. S i* ! mosphere is not deficient in oxygen. to make sure that air is being delivered to the wearer and | i nufacturer's j >. *1 lfined space \ 'hazardous,! is will served xit; (b) as a als between!! and ( c ) 1asrf| ; case of an*.n]$ uld be held-; is wearing (6) Enter the contaminated area cautiously. If the odor of the contaminant is noted, return to fresh air immediately and ascertain the cause of the leakage. (7) Make certain that the canister has enough residual life to give respiratory protection for the period that the wearer expects to be in the con taminated area. It is good practice to attach a fresh canister to the mask before entering an extremely hazardous atmosphere, especially one containing a gas that has poor warning properties, such as methyl bromide. " >'3 cautiously/f Dr, taste, or o fresh air tions of the in of time lip, or the the wearer' ; :*> i `1 the Use of , mask is in J n the body' ere is some (8) The facepiece should not be removed or fresh canisters attached until the wearer is certain that he is in respirable air. (9) After leaving the contaminated area, re place the bottom seal on the canister to prevent deterioration of the canister contents. This is par ticularly important in the case of universal gas-mask canisters. (10) Where the contaminant is a single gas or vapor, or a mixture of two or more gases or vapors of the same type, longer service time will be obtained if a canister is used that is designed especially for protection against the contaminant than would be obtained if a universal gas-mask canister were used. Firemen generally use the universal gas mask canister because they are never certain what gases they might encounter. facepiece. (6) Adjust the body harness securely to the wearer. (7) Adjust the facepiece to the wearer so that it makes a gastight fit with his face. There are two means of testing for a satisfactory facepiece fit: (a) Close off the exhalation valve and exhale gently into the facepiece. If a slight positive pressure can be built up in the facepiece without any indication of outward leakage of air between the facepiece and the face, it is adjusted properly, (b) Close off the breathing tube or tubes, inhale so that the facepiece starts to collapse, and hold the breath for about 10 seconds. If the facepiece stays in its partially collapsed conditions and no inward leakage of air is detected, it is adjusted properly. (8) Operate the blower, and adjust the flow of air to the wearer's satisfaction. The blower should be operated continuously during the use of the mask. (9) Check on the prearranged signals be tween the wearer and the blower operator. (10) Enter the contaminated area cautiously. (11) Be careful that the hose is not en dangered by sharp edges or falling objects, and re member that the wearer must retrace his steps and leave by the same route that he entered. (12) If the continuous flow of air to the facepiece is interrupted, the wearer should return to fresh air and ascertain the cause. (13) The facepiece should not be removed arer's head until the wearer is certain that he is in respirable air. * a gastight 7.5.2.3 Precautions To Be Taken in the Use of 7 .5 .2 .4 Precautions To Be Taken in the Use a Hose Mask With Blower of a Hose Mask Without Blower > means of ' (1) Make certain that the hose mask is in (1) Make certain that the hose mask is in Hose off the '* good operating condition. good operating condition. e facepiece. ' (2 ) Set the blower in an assured source of (2) Securely fasten the air-intake of the in the face- j respirable air. respirator in an assured source of respirable air. leakage of ) Z2.1 38 AMERICAN STANDARD SAFETY CODE FOR . 1 (3) Connect the proper length of hose (not over 75 feet) to the air-intake and to the face the wearer according to the manufacturer's instruc tions. A full facepiece or half-mask facepiece should piece, making sure that all gaskets are in place and be adjusted so that all the excess air leaves the that the connections are tight. facepiece through the exhalation valve and none : (4) Adjust the body harness to the wearer. is felt leaking out under the edge of the facepiece. , (5) Adjust the facepiece to the wearer so (6) When the rate of flow of air into the 1 that it makes a gastight fit with his face. facepiece, helmet, or hood seems to he excessive, the There are two means of testing for a satisfactory wearer may decrease the flow of air by means of facepiece fit: (a) Close off the exhalation valve and the air-regulating valve with which most air-line exhale gently into the facepiece. If a slight positive respirators are equipped. However, to prevent the pressure can be built up in the facepiece without contaminant in the surrounding air from reaching . any indication of outward leakage of air between the wearer's breathing zone, the flow of air should the facepiece and the face, it is adjusted properly. not be decreased below 4 cubic feet per minute for (b) Close off the breathing tube, inhale so that facepieces, or below 6 cubic feet per minute for * the facepiece starts to collapse, and hold the breath helmets or hoods. Hence, the air-regulating valve for about 10 seconds. If the facepiece stays in its should be used judiciously on an air-line respirator. partially collapsed condition and no inward leakage (7) Enter the contaminated area cautiously ' of air is detected, it is adjusted properly and is and leave by the same route. gastight. (8) Each air-line respirator is equipped with : (6) Make certain that the atmosphere to be a quick-acting detachable coupling by means of entered is not so hazardous that the wearer cannot which the wearer can quickly disconnect the respira escape unharmed without the aid of the respirator. tor from the air-supply line to facilitate escape in j (7) Enter the contaminated area cautiously an emergency such as fire. The wearer should practice | and leave by the same route. using this coupling before wearing the respirator 5 7.5.2.5 Precautions To Be Taken in the Use of in a contaminated atmosphere. :M an Air-Line Respirator 7.5.2.6 Precautions To Be Taken in the Use of ' l l an Abrasive-Blasting Respirator. The precautions to (1) Make certain that the air supply is respir be taken in the use of an abrasive-blasting respirator j | l able. Close attention should be paid to the location are the same as those given for the air-line respirator, M of the intake to the air-supply device to make certain that the entering air is not contaminated. A suitable with the following additional precautions. j filter should be provided to remove objectionable odors, oil and water mist, and rust particles from (1) Make certain that the shatterproof eye- a piece and the protective cover glass(if furnished) J the air delivered to the air-supply line. A suitable are in place. Under no circumstances should regular j reducing-type or demand-type valve and an excesspressure relief valve should also be provided. For window glass be used in place of the shatterproof eyepiece. Clean the inner and outer surfaces of all supplying respirable air, the use of low-pressure externally lubricated blowers is preferable to highpressure internally lubricated compressors, since the eyepieces. ; (2) Make certain that the protective wire screen or perforated-metal eyepiece is clean and in latter may add objectionable odors to the air and place. may produce carbon monoxide upon overheating. 7.5.2.7 Precautions To Be Taken in the Use of Internally lubricated compressors should be equipped a Chemical-Cartridge Respirator with an automatic shut-off which is actuated if they (1) Make certain that the atmosphere to be become overheated. entered is not dangerous to life. (2) Make certain that the air-line respirator (2) Make certain that the respirator is in is in good operating condition. good operating condition, that the gaskets are in (3) Attach the proper length of air-supply place, and that the proper chemical cartridges are hose to the source of compressed air and to the securely mounted in the respirator. breathing tube. (3) Adjust the respirator to the wearer's face (4) Adjust the pressure of the air at the inlet tq the air-supply hose so that it is within the proper so that it makes a gastight fit with his face. There are two means of testing for a gastight fit: (a) Close pressure range. (5) Adjust the facepiece, helmet, or hood to off the exhalation valve and exhale gently into the facepiece. If a slight positive pressure can be built HEAD, EYE, AND RESPIRATORY PROTECTION : up in the facepiece -without any indication of outward leakage of air between the facepiece and the face, it is adjusted properly, (b) Close off the inlets to the face piece by cardboard discs or stoppers usually furnished by the manufacturer, inhale so that the facepiece starts ; to collapse, and hold the breath for about 10 seconds. If the facepiece remains in its partially collapsed : condition and no inward leakage of air is detected, it is adjusted properly. If the second method is used, the cardboard discs or stoppers must be re- moved and the cartridges assembled with the face- \ piece without disturbing the fit of the facepiece on the wearer's face. v (4) Enter the contaminated area cautiously. (5) When leakage of the contaminant is noted 2 by the wearer, he should discard the used cartridges and replace them with fresh ones. i (6) Knitted cotton cloth must never be used to cover the face-contacting edges of chemical-car- | tridge respirators, since the cloth cover is not gas- 1* tight. 7 .5 .2 .8 Precautions To Be Taken in the Use of 1 a Dispersoid (Dust, Mist, or Fume) Respirator (1) Make certain that the respirator is in good operating condition and that the proper filters are securely fastened in place. (2) Adjust the respirator to the wearer's face so that it makes a dust-tight fit with his face. There are two means of testing for a satisfactory facepiece fit: (a) Close off the exhalation valve and exhale gently into the facepiece. If a slight j positive pressure can be built up in the facepiece without any indication of outward leakage of air i between the facepiece and the face, it is adjusted 1 properly, (b) Close off the inlets to the facepiece ; by cardboard discs or stoppers usually furnished j by the manufacturer, inhale so that the facepiece ; starts to collapse, and hold the breath for about 10 | seconds. If the facepiece remains in its partially collapsed condition, and no inward leakage of air : is. detected, it is adjusted properly. If the second | method is used, the cardboard discs or stoppers must '! be removed and the filters assembled with the face; piece without disturbing the fit of the facepiece on ' the wearer's face. Z2.1 39 filters should be cleaned in accordance with the manufacturer's instruction. Under no circumstances should respirator filters be washed or dry cleaned. (4) In atmospheres containing particulate matter that is irritating to the skin, or where excessive perspiration may occur, a knitted cotton cloth, furnished by the manufacturer, may be used over the edge of the facepiece to prevent contact between the rubber portion of the facepiece and the wearer's face. This must not be used on fume respirators. (5) When the facepiece is removed, the wearer may obtain visual evidence of the dusttightness of the facepiece fit by looking at his re flection in a mirror and noting the presence or absence of dust streaks on that portion of his face that was covered by the facepiece. 7.5.3 Instruction in Use of Respirators 7.5.3.1 General Considerations. For the safe use of any device, it is essential that the user be properly instructed in its selection, use, and mainten ance. This is particularly important with respect to respirators. Competent persons should give such instruction to the supervisors of all groups who may be required to wear respirators at their work. The supervisors, in turn, should instruct their men. No person should be allowed to wear a respirator of any type until he has received such instruction. Such instruction should cover: (1) An explanation of the need for using the respirator (2) Its operating principle (3) Steps to be taken to assure that it is in good operating condition (4) Proper adjustment of the respirator to the wearer (5) Proper use and maintenance of the res pirator The very presence of self-contained breathing apparatus, hose masks with blowers, or gas masks on the property of any organization is an indication that they are expected to be used in an emergency situation or in one that is dangerous to life. All persons who may have occasion to use these respira tors, or cause them to be used, should be properly trained in their use before circumstances require that they use them to protect their lives and the property of their em ployer. In addition to this, efforts should be made to foresee possible emergencies and plans of action should be formulated so that when re sp ir atory protection is needed, rescue or repair operations will proceed smoothly and safely. Merely talking about such respirators as the self- Z2.1 40 AMERICAN STANDARD SAFETY CODE FQRj contained breathing apparatus, the hose mask with blower, and the gas mask is not enough. The men should be given an opportunity to handle the respira tor, have it fitted to them properly, test the gaslightness of the facepiece fit, wear it in normal air for a period long enough for them to become familiar with it, and, finally, they should actually wear it in an irrespirable atmosphere. Such an atmosphere may be created by burning a half-ounce formaldehyde candle in a room of about 4,000 cubic foot capacity. Not only would this atmosphere be irrespirable, but it would be irritating to the eyes. This atmosphere is similar to that used by the Bureau of Mines in the training of men in the use of the self-contained breathing apparatus. After a person has worn one of these devices for a prolonged period in this formaldehyde-air mixture without any ill effect, he need only remove the facepiece or nose clip moment arily to be convinced of the efficacy of the respirator. Such training breeds confidence in the trainees that should stand them in good stead in an emergency situation.- A less severe training atmosphere that can be built up in any room without damage to its contents, or to other people in the same building, may be prepared by vaporizing isoamyl acetate to the amount of 173 cubic centimeters per 1,000 cubic foot capacity of the room. The liquid isoamyl acetate is vaporized from a cloth wick placed in front of a fan in the room. This produces a concentration of about 1,000 parts of isoamyl acetate per million parts of air (0.1 percent) by volume. If the odor of isoamyl acetate is detected by a person wearing an emergencytype respirator, he would be able to detect the odor of phosgene or chlorine if he entered a 2-percent concentration of either of these gases while wearing the device. Isoamyl acetate vapor in this concentra tion is used by the Bureau of Mines as a preliminary means of testing the gastightness of gas-mask face pieces before actually wearing them in highly toxic concentrations of gases. should be equipped adequately and manned by$ trained personnel. ^ 7.5.4.2 tors Procedures Applicable to All Respira 7.5.4.2.1 Inspection. All respirators should be inspected at regular intervals to make sure that | they are ready for use. For respirators that are used and maintained daily, inspection becomes a rather automatic function; however, it is often neglected for respirators that are stored throughout a plant for use in emergency situations. These device* should be checked as regularly as fire extinguishers;, as a matter of fact, it is good practice to integrate these inspection and maintenance programs. - All rubber parts such as facepieces, mouthpieces, 4 exhalation valves, breathing tubes, and headbands1 should be inspected carefully for signs of deterioration such as hardening, checking, or tackiness. During the inspection, time should be given to "working" the rubber between the fingers with a stretching and massaging action. This will reveal defects in rubber parts and prolong the life of non-defective parts. A check should be made to see that all gaskets are present and that they are held in place tightly, ,: Metal parts should be checked for signs of cor rosion, and plastic and glass parts for breakage. 7.5.4.2.2 Maintenance. When it is necessary to replace worn or deteriorated parts, only those made specifically for the device should be used and the repair work should be accomplished by experi enced personnel. Makeshift repairs for respiratory protective equipment cannot be tolerated. After equipment that is used frequently is cleaned and disinfected, it should be repaired routinely; emer gency equipment should be repaired immediately after inspection reveals the need for repairs. ' Repairs to intricate parts should not be attempted unless adequate facilities and trained personnel are available. For most users, it is preferable that parts of this type be replaced as a unit or returned to the manufacturer for repair. 7.5.4 Maintaining, Cleaning, Disinfecting, and Storing Respirators 7.5.4.1 General Considerations. It is especially important that respirators be properly maintained and stored. The life of the wearer may be dependent on their proper functioning and ready availability. Adequate attention to cleaning and disinfecting is also required because the respiratory inlet coverings are worn on the face. Whenever possible, a centralized maintenance, cleaning, and storage station should be established to care for equipment of this type. It 7.5.4.2.3 Cleaning and Disinfecting. Respir atory protective equipment should be cleaned and disinfected after each use. However, because of the wide variety of materials used in these devices, the manufacturer should be consulted for the cleaning and disinfecting method best suited to his products. In general, facepieces and mouthpieces for respir atory protective devices are made from rubber or rubber-like compounds. Usually, these can be cleaned with detergent and lukewarm water by h and-brushing or agitation in a washing machine. Formaldehyde, Z2.1 [HEAD, EYE, AND RESPIRATORY PROTECTION 41 lodified phenolics, hypochlorite, or quaternary amionium compounds in the proper strength can be Raed to disinfect the parts. Normally all detergent is [rinsed from the protective device before disinfecting; [however, there are several combination cleaning and disinfecting materials available id both liquid and Kowder form which contain a detergent and quater nary ammonium salts and this permits combining the fashing and disinfecting operations. After cleaning pnd disinfecting, the parts should be rinsed in clean rater and dried quickly for most disinfectants. It may pot be desirable to rinse parts treated with quaternary [ammonium compounds since their disinfectant prop erties will continue indefinitely and may not produce fa skin irritation. After reassembly, the device should [be placed in a clean and dust-tight container. replaced after use and that the oxygen cylinder is re filled to rated capacity in order to insure full service life. The cylinder pressure should be checked peri odically and brought to rated pressure if necessary. The tightness of the high pressure and low pressure sides of the apparatus should be checked periodically following the manufacturer's instructions. In self generating apparatus, periodic tightness tests as out lined by the manufacturer should be followed, 7 .5 .4 .3 .2 Hose Masks. Check the blower pe riodically for proper operation. Check hose for wear and tear after each use and steam clean when neces sary, Keeping hose capped when not in use will pre vent entrance of dust or other contaminants. 7 .5 .4 .3 .3 Air-Line Respirators. The face piece should be serviced after each use just as for all Hot w^ter, steam, solvents, and ultraviolet light other respiratory protective equipment. The flow- ^should be avoided in the cleaning and disinfecting of control valves should be inspected after each use and [rubber parts because all have deteriorating effects. If cleaned and repaired if necessary. Chemical car paint or other difficult-to-remove substances are en tridges in the continuous-flow control-valve assemblies countered, it is preferable that they be removed by should be changed when necessary. Air-line hose [mild caustic cleaners rather than by solvents. should be checked for wear and tear after each use m>6 7.5.4.2.4 Storage. All types of respiratorasnd be steam cleaned when necessary. ishould be stored in clean and dry compartments tmder The air-supply system should be inspected routinely [conditions of moderate temperature. Most devices of to insure continued proper functioning. Air compres .this type are received in re-usable cartons or cases and sors, air-cylinder manifold systems, pressure reducers, should be kept in these containers during the period pressure-release valves, air-line filters, air-line instru of storage. Exposure to heat, sunlight, extreme cold, mentation, and permanent piping and outlet fittings and excessive moisture is harmful to respiratory pro must be kept in good repair to assure satisfactory tective devices if the exposure continues over ex condition of the air reaching the breathing zone of the tended periods. wearer. In some cases, it is necessary to locate respiratory 7 .5 .4 .3 .4 Gas masks. Check the facepiece to leanecUana protective devices at convenient stations throughout be sure that (1) the eyepieces are not broken and id y ;, emep the work area for ready availability in the event of an that they are held firmly in place; (2) the rubber rmnediately emergency. Special care must be taken to insure ade portion of the facepiece is flexible and free from airs. quate storage under these conditions. In some in cracks; (3) the head harness is flexible and that the 3attempted stances, it is necessary to construct special compart straps and buckles are in good condition; (4) the rsonnelfai. ments to protect the equipment from the process mate exhalation valve is in place, works freely, and has no : that pa' rials as well as from the elements. dirt on its contact surfaces; (5) the breathing tube is med to: Additional emergency-type respiratory protective flexible and free from cuts and that it is securely devices should be stored just outside the immediate fastened to the canister neck or to the outlet of the ag. Respir leaned am iuse of -the levices, ths >e cleaning ^ products, for respirruhber or danger area so that men can retreat to them and don timer; (6) the canister is of the proper type, is free them for judicious re-entry into the contaminated from dents and rust spots, and is securely attached to area to carry out rescue or repair operations. the canister harness. If a timer is used, check to be No respirator can be adequately stored outside its sure that the gaskets are in place and are making carrying case or carton in a tool box or clothing proper contact, and that the timer is reset when a new locker. canister is attached. Universal gas-mask canisters should be replaced after one year from date of break 7.5.4,3 Special Procedures for Maintaining, ing seal if not exhausted before this time. Canisters Cleaning, Disinfecting, and Storing Respirators sh o u ld he sto re d 5n a co o l, clean, d ry location an d th e be cleaned id-brushing maldehyde, 7.5.4.3.1 Self-Contained Breathing Apparastock rotated so that no canister remains in storage tus. In compressed-oxygen recirculating apparatus, for more than four years before it is used. make sure the carbon dioxide removing chemical is 7 .5 .4 .3 .5 Self-Rescuers. Frequent inspection Z2.1 42 is the most important phase of the maintenance pro gram with this type of equipment beoauso the equip* ment is seldom used but must always be ready. The type which offers protection against carbon monoxide utilizes hopcalite in the chemical fill and must be pro tected from moisture to remain effective. Follow the manufacturer's recommendations for checking the moisture seal at regular and frequent intervals. Some respirators employ re-cleanable filters, in which case the filters are cleaned when the respirator is being serviced. Chemical cartridges should be changed when the wearer detects the odor or irritating effect of the con taminant. In plants with centralized maintenance sta tions, cartridges are sometimes discarded after a given period of use (based on group experience), but in most cases the wearer is responsible for discarding 7.5.4.3.6 Dispersoid and Chemical-Cartridgaend replacing cartridges in his respirator. Respirators. Mechanical filters of the "throw-away" Particular care should be exercised in the storage type should be discarded when the breathing resist of chemical cartridges because they usually" deteri ance becomes bothersome to the wearer. In most orate if exposed to excess moisture and to gaseous air plants with centralized maintenance stations, the fil contaminants. Cartridges should not be stored in the ters are destroyed and discarded at the time the respirator is serviced. area where it is necessary for the workmen to use chemical-cartridge respirators. afr nagte