Document 5DNk2RX9ORaojejpbg1zxypgN

78 CHAPTER 7 1959 Guide Table 3 .... Maximum Allowable Concentration of Gases and Vapors (Conc/w/ed) Substance ASA hrcthold UmH Valve* Stond- ACGIH4 1958 MAC PP** by PP"b oz/1000 cu ft Methyl chloroform (1-1-1 tri- Methyl isobutyl carbinol Methylene chloride (dichloro- Pentanone (methyl propyl kePerchlorethylene (tetraPhosgeoe (carbonyl chloride).. Propyl alcohol (isopropyl alPropyl ether (isopropyl ether). Propylene dichloride (1,2- Styrene monomer (phenyl- 1,1,2,2-Tetrachloroethane... Trifluororoonobromomethane. Vinyl chloride (chloroetbylene 500 2.700 2.000 100 0.470 100 0.460 100 0.250 25 0.100 500 1.750 200 0.800 500 2.000 0.001 0.000007 10 0.025 1 0.006 0.005 LOO 0.5 0.310 0.009 0.005 0.250 50 5 500 0.1 0.180 0.030 2 350 0.0002 2.950 200 0.700 200 5 5 1 0.05 1.350 0.019 0.022 0.004 0.00007 200 0.840 400 0.980 500 2.100 75 25 10 0.1 0.1 500 400 100 5 1000 5. 200 . 200 200 200 1000 100 500 200 0.350 0.060 0.030 0.0004 0.0005 2.90 0.420 0.013 6.000.. 0.006 0.00025 0.060 0.035 0.590 0.008 0.750 0.022 1.050 6.100 0.560 1.30 0.870 tion which may be associated with severe and irreversible injury. 5. These values are upper limits; it is desirable to operate well below the levels if the engineering and economic factors permit. The prudent engineer will incorporate a reasonable margin of safety in his estimates of ventilation capacity. In Table 3, Column 1 lists the ASA Sectional Committee Z37 MAC values; Column 2, those of the ACGIH Commit tee on Threshold Limits. Column 3 gives the value in grams per cubic meter or ounces per 1000 cu ft for the corresponding ACGIH limits. In Table 4, Columns 2 and 3 are respectively the MAC values from the ASA and ACGIH Committees. In Table 5, the MAC values for industrial dusts as given were obtained from data of the ACGIH Committee on Threshold limits. ACGIH limits for either gamma or Roentgen radiations are 03 roentgens per week. Information on the properties and effects, with respect to health, of specific industrial air contaminants is available in publications listed at the end of this chapter. FLAMMABLE GASES AND VAPORS Adequate ventilation is a primary requirement for mini mizing the hazard of fire or explosion due to gases and vapors. The need for good ventilation is not removed by the use of other precautions, such as the elimination of known ignition sources, segregation of hazardous operations, adoption of safe building construction, and installation of automatic alarms. Some safety engineers regard overventilation of ah operation employing flammable liquids as a legitimate oper ating charge for the privilege or necessity of using a danger ous process. However, it is not possible to apply a reasonable safety factor to the ventilation estimate without considera tion of the concentrations of gases or vapors that approach the danger point. Safety engineers prefer to limit the concen tration to Va or Vb of the lower explosive limit, and this fact should be given full weight in determining the capacity and design of ventilating equipment. Rarely should consideration be given to operation c&ove the upper explosive limit in the open areas of buildings or rooms--even though unoccupied-- because the danger of temporary drop of gas concentration to a point within the explosive range is too great. Ability of a flammable liquid to form explosive mixtures is determined largelyby its vapor pressure, volatility, or rate of evaporation. Flash point is a convenient method of ex pressing this property in terms of the temperature scale. It may be defined as the temperature to which a combustible liquid must be heated to produce a flash when a small flame is passed across the surface of the liquid. The higher the flash point, the more safely can the liquid be handled. Liquids with flash points under 70 P should be regarded as highly flammable. Upper and lower limits of flammability of gases and vapors, and the flash points of the corresponding liquids are given in Table 6. Methods for estimating the flammable limits of mixtures of gases or vapors must be applied with caution; the reader is referred to other publications for this information.1*' Design of equipment for the control of combustible anes thetics is outlined in Chapter 8. Construction of equipment for handling air containing flammable substances, or operat ing in atmospheres so contaminated, is discussed in Chapter 52. It is customary to report the concentrations of flammable Air Contaminants 79 Table A .... Limits for Toxic Dusts, Fumes, and Mists ASA Stond- MAC, Hired)old limif Volues, ACGIH 1958 q/cb ai4 Aldrin (1,2,3,4,10,10-bexachloro-l,4,4a, 5,8,8a-hexahydro-l ,4,5,8-dimeth- anonaphthalene).................................. Animate (ammonium sulf&mate)............. Antimony................ .................................. (x) ANTU (alpha naphthyl thiourea)........... 0.00025 0.015 0.0005 0.0003 Arsenic............................................................ Barium (soluble compounds)..................... Cadmium oxide fume................................... (x) Calcium arsenate.......................................... Chlordane (1,2,4,5,6,7,8,8-octachloro- 3a,4,7,7a-tetrahydro-4,7-metbanoindane).............................................. 0.0005 0.0005 0.0001 0.0001 0.002 (x) Chlorinated camphene (60%)........... ......... Chlorinated diphenyl oxide........................ Chlorodiphenyl (42% chlorine)................. (x) Chlorodiphenyl (54% chlorine)................. Chromic acid and chromates (as CrO). . 0.0001 0.0005 0.0005 0.001 0.0005 0.0001 Crag herbicide (sodium 2-[2,4-dichlorophenoxy]ethanol hydrogensulfate) :. Cyanide (as CN)........................................... 2,4-D(2,4-dichiorophenoxvacetic acid)... (x) DDT (2,2-bis{p-chlorophenyl]-l,l,l,trichloroetb ane.......................................... 0.015 0.005 0.010 0.001 . Dieldrin (1,2,3,4,10,10-hexachloro-6,7epoxy-1,4,4a, 5,6,7,8,8a-octahydro- 1,4,5,8-diroethanonaphthalene)........ (x) Dinitrobenzene.............................................. Dinitrotoiuene............................................... Dinitro-o-cresol............................................. 0.00025 0.001 0.0015 0.0002 EPN (O-ethyl O-p-nitropbenyl thiono-' benzenephospoonate)........................... (x) Ferbom (ferric dimethyl dithiocarbamate) Ferrovanadium dust..................................... Fluoride.......................................................... 0.000.5 0.015 0.001 0.0025 Hydroquinone................................................ 0.002 Iron oxide fume............................................ 0.015 Lead................................................................ 0.00015 0.0002 (x) l,ead arsenate................................... ............ 0.00015 Lindane (hexachlorocyclohexaae, gamma isomer)..................................................... 0.0005 Magnesium oxide fume................................ Malathion (O.O-dimethyl dithiophos- phate of diethyl mercaptosuccinate).. Manganese...................................................... 0.006 Mereury.................................... ................... 0.0001 0.015 0.015 0.006 0.0001 Mercury (organic compounds)................... Methoxychlor (2,2-di-p-methoxyphenyl- 1,1,1-trichloroethane).......................... Molybdenum (soluble compounds)................................ (insoluble compounds)............................. 0.00001 0.015 0.005 0.015 (x) Nicotine........................................................ Parathion (0,0-diethyl O-p-nitrophenyl thiophosphate)..................................... Pentachloronaphthalene........................... Pentachlorophenol...................................... Phosphorus (yellow)............ ................... 0.0005 0.0001 0.0005 0.0005 0.0001 Phosphorus pentachloride Phosphorus pentasulfide.. Picric acid....... .................. Pyrethum........................... (x) Rotenone ........................... 0.001 0.001 0.0001 0.002 0.005 Table A .... Limits for Toxic Dusts, Fumes, and Mists (Concluded) ASA ThretfxM Graff Stend- Values. MAC, 9/co m4 ACGIH 1958 fl/ew Selenium compounds (as Se) (x) Sodium fluoroacetate (1080). Sodium hydroxide....... ........... (x) Strychnine................................ Sulfuric acid............................ TEDP (tetraethyl dithionopyrophosphate).................................... ............... TEPP (tetraethyl pyrophosphate)............ Tellurium....................................................... . Tetryl (2,4,6-trinitropbenylmethyInitra- mine)....................................................... (x) Thiram (tetramethyl thiuram disulfide).. (x) Thallium (soluble compounds)................... Titanium dioxide.................... Trichloronaphthalene.. \............................ Trinitrotoluene............................................. 0.0001 0.0001 0.002 0.00015 0.001 0.0002 0.00005 0.0001 0.0015 0.005 0.0001 0.015 0.005 0.0015 Uranium...................................................................... (soluble compounds)................................ (insoluble compounds)............................ Vanadium....................................................... (Vrf> dust)................................................ (V,0* fume)............................................... . (x) Warfarin (3-(a acetonylbenzylj-4-hy- droxycoumarin).................................... Zinc oxide fumes.......................................... Zirconium compounds (as Zr)................... 0.00025 0.0005 0.0001 0.0005 0.015 0.005 Grama of dust, fume. Or mist per eubio meter of air. (1) These values appeared ou the ACGIH tentative tat, far 1956. Badkaettvity: For permissible concentrations of radioisotopes in sir, see Haximun PermittM* Asmunit tf Rciioitrtope* ta Us Hume* Bodj and Harimuat PermicsibU Concentration* in Air end Water, Handbook 52, O. S. Depart ment of Commerce. National Bureau of Standards, March, J953. In addition, see PcrmissibU Dots from External Source* tf lonions Radiation, Handbook 69, U. S. Department of Commerce, National Bureau of Standards, September 24, 1954. Table 4 values reprinted by permisraoa from AHA Archive* cl Industriel Health, September 1957, Vel. 16, pp. 261-265. No changes were made by AC01H Committee on Threshold Limits at 1958 meeting. - Table 5 .... limits for Mineral Dusts Threshold UmH Values ACGIH 1958 mppcf* Aluminum oxide......................... Asbestos............. ......................... Cement, Portland........ .......... Dust (nuisance; no free silica) Mica (below 5% free silica).............. Silica--high (above 50% free SiO). Silica--medium (5 to 50% free SiOt) Silica--low (below 5% free SiOt). . . Silicon carbide............................ Soapstone (below 5% free'SiO*) Talc................................................ 50 5 50 50 20 5 20 50 50 20 20 4 mppcf--million particle* per cubic foot of air, standard light held count. Table 6 values reprinted by permisrioa from AHA Archive* of Industrial Health, September 1957, Vol. 16, pp. 261-265. No were made by ACGIH 'Committee bn Threshold Limits.in 1956. X