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FIRE PROTECTION oil or paint often cause fires too The NFPA Committee on Spontaneous Heating and Ignition recommends a detailed proce dure for the prevention and extinguishment of fires in these materials The best preventives against spontaneous ignition are either total exclusion of air or good ventilation With small quantities of material, the former method is practicable With large quantities of material, such as storage piles of bituminous coal, both meth ods have been used with success Temperatures of 140 F are considered dangerous in coal piles If temperatures rapidly approach or exceed that figure, it is generally advisable to move the pile or re arrange it to allow better circulation of air. Certain agricultural products are suscep tible to spontaneous ignition. Sawdust, hay, gram, and other plant products such as jute, hemp, and sisal fibers may ignite spontane ously, especially if exposed to external heat or to alternate wetting and drying Here again, the best preventive is circulation of air, removal of external sources of beat, and storage of material in smaller quan tities. Fires m iron, nickel, aluminum, magne sium, and other finely divided metals are sometimes attributed to spontaneous igni tion believed to result from the oxidation of cutting or lubricating oils or possibly from chemical impurities. Fig 33-14a A sheet metal waste can of standord construction which prevents opening the cover more than 60 degrees from the horizontal, thus ensuring auto matic closing Housekeeping Collection and storage of combustibles Many industrial fires are the direct result of accumulations of oil-soaked and paintsaturated clothing, rags, waste, excelsior, and combustible refuse Such material should be deposited in noncombustible receptacles, having self-closing covers, that are provided for this purpose and removed daily from the work areas (Fig 33-14) Exhaust systems of effective design will remove gases, vapors, dusts, and other air borne contaminants--many of which mav be fire hazards. Exhaust systems and machine enclosures will help to prevent accumulation of flammable materials on the floors or on machine parts Such materials are most hazardous when airborne rather than when they have settled out Clean waste, although not as dangerous as oil-soaked waste, is readily combustible and should be kept in metal cans or bins with self-closing covers Excelsior, cotton, ka pok, jute, and other highly combustible fibrous material should be stored in cov ered Doncombushble contamers and, if large quantities are kept on hand, m fire-resistant rooms equipped with fire doors and auto matic sprinklers Portable extinguishers, hose lines, or other Class A extinguishing equipment for Class A fires should be avail- 0 National Fire Protection Association, 60 Batterymarch St, Boston, Mass Table of Materials Subject to Spontaneous Heat ing, Standard No. 492. and Spontaneous Ignition of Coal and Other Mining Prod ucts, Standard No 493. 33-2?