Document 1Qa9YwgkZYKnOVgL8Qy5oOgQo

88 CHAPTER 7 1960 Guide Table 8 .... Limits for Toxic Dusts, Fumes, and Mists Thrathald limit aids MAC, g/ca a* ACCiH 1959 g/cv Substance erdt MAC, g/ca a' Vohat, ACGfH 1959 q/cu m* Aldrin(l,2,3,4,10,10-hexfcchloto~l,4,4a, 1 5,8,oa-hexahydro-l,4,5,8-<limethaoonaphthalene).................................... Aminat* (ammonium sulfamatc)............... Antimony................................ ..................... ANTU (alpha naphthyl thiourea)............. Arsenic............................................... ............ I , 0.00025 .0.015 0.0005 0.0003 0.0005 : Barium (soluble compounds)..................... (x) Beryllium..................... ............... Cadmium oxide fume................................... Calcium arsenate.................. ............. Chlordane (1,2,4,5,6,7,8,8-octacbloro- 3a, 4,7,7a-tetrahydro-4,7-methanoindane).............................................. 0.0005 0.000002 0.0001 0.0001 0.002 Chlorinated camphene (60%)..................... Chlorinated diphenyl oxide.................. . Chlorodiphenyl (42% chlorine)...... ........... Chlorodiphenyl (54% chlorine)................. Chromic acid and chromates (as CrOj) . 0.0001 0.0005 0.0005 0.001 0.0005 0.0001 Crag herbicide (sodium 2-12,4-dichloro- phenoxy) ethanol hydrogen sulfate) . Cyanide (as CN)....................................... 2,4-D(2,4-dichlorophenoxyflcetic acid) ' DDT (2,2-bis[p-cbJorophenyI]-l, 1,l,tri- chloroethane........................................... 0.016 0.005 0.010 0.001 Dieldrin (1,2,3,4,10,lO-hexacMoro-6,7epoxy-ll4,4a,5,6,7,8,Sa-octahvdro' l,4,5,8-4imethaDonaphthalene) ......... DLmtrobeoiene.............................................. Dinitrotoluene............................................... THnitro-O'Cresol................... ......................... 0.00025 0.001 0.0015 i 0.0002 i Molybdenum (soluble compounds) . (insoluble compounds) Nicotine.................... -............................... . Parathion (O,O-diethyl O-p-nitropbeayl thiophosphate)........................................ Pentachloronaphthalene.............................. Pentachlorophenol........................................ Phosphorus (yellow)....................................| Phosphorus peotachloride........ Phosphorus pentasulfide........... Picric acid................................... Pyretbum..................................... Kotenone...................................... Selenium compounds (as Se);...... Sodium fluoroaeetate (1080).. Sodium hydroxide........... ................. Strychnine............................................. Sulfuric acid......................................... TEDP (tetraethyl dithionopyrophogphate)...................................................... . TEPP (tetraethyl pyrophosphate)............ Tellurium............... ,..................................... . Tetryl (2,4,6-trimtropbenylmethylnitra- mine).................................................. . Thiram (tetramethyl thiuram disulfide)... Thallium (solublecompounds)................ Titanium dioxide...................................... Trichloronaphthalene............................... Trinitrotoluene.......................................... 0.005 o;oi5 0.0005 0.0001 0.0005 0.0005 0.0001 0.001 0.001 0.0001 0.002 0.005 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 EPN (O-ethyl O-p-nitrophenyl thionobenxenephospnonate)...................... .. Ferbam (feme dimethyl dithiocarbamate) Fenovan&dium dust.................................. Fluoride.......................................................... 0.0005 0.015 0.001 0.0025 Hydroqumone................................. .............. 0.002 Iron oxide fume..................................... . .. Lead................................................................ 0.00015 0.015 0.0002 Lead arsenate............... ................................ T-inrian* (bexacblorocyclohexane, gamma 0.00015 isomer).................................................... 0.0005 Magnesium oxide fume................................ Malathion (0,0-dimethyl ditbiophoe- phate of diethyl mercaptosuccinate).. Manganese..................................................... 0.006 Mercury.......................................................... 0.0001 Mercury (organic compounds)................... Methoxycblor (2,2-di-p-methoxyphenyl- 1,1,1 -trichloroethane).......................... 0.015 0.015 0.006 0.0001 0.00001 0.015 Uranium................................ (soluble compounds).. .. (insoluble compounds).. Vanadium........................... (V*0 dust)........................................... .. (V*0* fume)........................................... Warfarin (3-fn acetonylbeaxyl)-4-bydroxycoumario)................................. Zinc oxide fumes....................................... Zirconium compounds (as Zr)................ 0.00005 0.00025 0.0005 0.0001 0.0005 0.015 0.005 * Gruaa of dost, futoe, or mist Per cubic outer of air. (x)Thw vatowaddad to tbe U*fc in. M59. RaiBoactiytty: For permissible cooeestretwas of radioaotflpe* in air, see Maximum PtnitatHU i*ufa af Badiadaotopaa in tie Suntan Body ttnd Maxi mem PtrmittibU Concentration* t* Air and Water, Handbook 53, U. 8. Depart ment of Commerce. NationalBureau of Standards, March. 1953. Id addition, sue PtrmimibU Dam from External Swam af /mumt Radiation, Handbook 59, U. 8. Deportment of Commerce, National Bureau of Standards. September 14, US4. Table 8 value* reprinted by permsafan of tbc ACGIH Committee on Threebold Iimita. and the flash points of the corresponding liquids are given in Table 9. 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 tins information.** " 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, Industrial 'Exhaust Systems. It is customary to report the concentrations of flammable gases or vapors in percent by volume, or volume percent. Comparison with concentrations on the part per million scale used in chemical, metrical, or industrial hygiene literature is readily made by the conversion: 1 percent = 10,000 ppm (parts of contaminant per million parts of air, by volume. i Air Contaminants 89 Table 9. -. Approximate limits of Flammability ofSingle Oases and Vapors In Air at Ordinary Temperatures and Pressures* lw Hoof Parcaat 57. Vduma Uapwr Utail Pcrcard Voiome Clatad Cop* Fhdt Paiel FuftrenheU H&FU 3o*sScofioa* lever limit Parcarsf by Vofoma Clatad Uppar Cap* NBHJ Radi Clotd- by Volinas Pood xduw ball fleodotP Acetaldehyde.............. Acetone......... . Acetylene................... Ally! alcohol....----Ammonia.................... Amyl alcohol.......... Amyl chloride........... Amylene...................... Benzene (benzol).... Benzyl chloride......... Butane......................... Butyl acetate............ Butyl alcohol............. Butylene..................... Carbon disulfide..... Carbon monoxide___ Crotonaldehyde......... Cyclohexane............... Cyclopropane............ Decane.'..................... Dichloroethylene (l, 2)......... Diethyl eelenide...................... Dioxane..................................... Ethane................... ................. - Ether (diethyl)........................ Ethyl acetate......................... Ethyl alcohol........................... Ethyl bromide........................ Ethyl cellosolve..................... Ethyl chloride........................ Ethylene................................. Ethylene dichloride.............. Ethyl formate........................ Ethyl nitrite.......................... Ethylene oxide....................... Furfural (125 C)........... ......... Gasoline (variable)............... Heptane.................... -- Hexane..................................... Hydrogen cyanide............. Hydrogen. .............................. Hydrogen sulfide................... Illuminating gas (coal gas) Ieobutyl alcohol................... Isopentane.............................. 4.0 2.5 2.5 2.5 15.5 1.2 1.6 1.6 1.3 ..1.1 57 12.8 $n 26.6 7.7 6.8 -17 0 70 100 12 140 I I ii III III 1.8 8-4 1.4 15.0 84 in 1.7 2.0 9.7 1.2 50 -22 I 12.5 2.1 1.3 2.4 0.67 74.2 15.5 8.4 10.5 2.6 9.7 12.8 2.5 2.0 22.2 3.1 12.5 1.8 36.5 2.2 . 3.3 . 6.7 . 2.6 . 4.0 11.5 19.0 11.3 15.7 14-8 . 2.7 . 6.2 . 2.7 . 3.0 . 3.0 28.6 15.9 16.5 50 80 . 2.1 . 1.4-1.5 7.4-7J . 1.0 6.0 . 1-2 6.9 40.0 55 II 1I 115 III 57 II 54 II -49 I 28 II 54 II 104 III --58 - I 56 -4 II I -31 I 140 -50 .IIII 25 II -15 I . 4.0 . 4.3 . 5.3 . 1.7 74.2 45.5 33.0 82 III 1 ] i 1 j Propane.......................... Propyl acetate.............. Propyl alcohol............... Propylene..................... Propylene dichloride.. Propylene oxide.......... Pynaine.......... ............ Toluene (toluol).......... Turpentine................... Vinyl ether................... Vinyl chloride.............. Water gas (variable).. Xylene (xylol)............. 1.8 7.8 2.0 5.0 15.0 3.1 15-5 '35.5 43 II 53 II 14 I 52 II 13.5 1.2 8.2 1.1 2.0 14.5 8.0 18.7 10-1 25 -35 II I 1.8 9.5 5.0 22.7 30 --2 II I 1.5 8.2 4.3 .13,5 1.1 6.0 20-110 HI. 0.9 0.83 ' 2.9 0.95 3.2 1.3 1.4 7.8 176 Ill 88 m 56 II 2.1 10.1 1.8 8.0 2.1 13.5 2.0 11.1 3.4 14.5 58 II 59 II 60 H 2.0 22.0 1.8 12.4 1.3 7.0 0.8 1.7 27.0 74 III 40 H 95 III 4.0 21.7 .... 6.0 70 }___ 1.0 6.0 63 II * Adapted from: Pir* and Expiation Hatari* ef CouibuttibU Pages and Vagan, by G. W. Jones; Chester IS,' Industriai BptionoandJTosKaloft, edited by F. A. Petty (latemaeace PubUaben, IMS); Propcrtie* efFlammable Liquid*, Gam* sod Solid* (Amodalad) Factory MutualFire Isa. Cob., laaaxty (1949); acd National Pin Cairn far Flamveable Liquid*, Gem*. Clnaeab end Brpiaaat*--1JKS (Na tionalFirs Prutactioa Aaaomxtiaa.). b Clami cup refer* to tbe equipment ueod in flash paiei determinations. Proa* Standard* for Stomp*, BandUnp and Urn af FlomamM* Liquid* (Na tional Board of Fire Underwriter*, No. 80, July 1984). or in other words, cubic feet of contaminant per million cubic feet of air). It will be noted in Table 9 that nearly all of the substances listed have lower explosive limits above 1.0 per cent, while the maximum allowable concentrations for gases and vapors in Table 6 are below 1000 ppm or 0.1 percent in most cases. Therefore, control of toxic or injurious vapors to levels below their maximum allowable concentrations for health usually requires much more effective ventilation than for the prevention of a fire hazard. COMBUSTIBLE DUSTS A dust explosion is essentially a sudden pressure rise caused by the very rapid burning of airborne dust. The primary ex plosion often originates from a small amount of dust in sus pension exposed to a source of ignition and the pressure and*'' vibration it creates may be sufficient to dislodge large accu mulations of dust on horizontal ledges or surfaces of the building and equipment, thereby creating a secondary ex plosion of great force. Thus the air-conditioning engineer is involved for two reasons: (1) to obtain a movement of dust laden air into exhaust hoods or openings, and through venti lating. or pneumatic conveying ducts, in a manner that will prevent accumulation of highly flammable dust at points where it could ignite inside the equipment; and (2) to so de sign process ventilation as to prevent the escape of dust which might settle on horizontal surfaces and become a po-