THE FIGHTING OF FIRES WHICH INVOLVE CHEMICAL HAZARDS
This Instalment Deals with Chemical Hazards from Liquids (Continued)—Oils and Flammable Liquids — Dangerous Solids
For the accompanying article, the ninth installment of which is published herewith, FIRE ENGINEERING is indebted to the Official Publication of the Iowa State College of Agriculture and Mechanic Arts, it being comprised in Bulletin No. 9, Engineering Extension Service:
Chemical Hazards from Liquids
Oils and Flammable Liquids (Continued)
Acetates. There are many volatile solvents such as amyl and butyl acetates which present serious fire and explosion hazards. Those used in the pyroxylin lacquers are especially dangerous since the lacquer is usually applied by spraying. This allows diffusion of the material in air presenting hazards similar to dust clouds. The pyroxylin base is made up from nitrocellulose which is an additional fire and fume hazard. These solvents and lacquers are common in paint shops and garages. All spraying should be done in an approved booth equipped with automatic sprinklers, Foam, soda-acid extinguishers, and water are very effective on fires in this material.
Carbon disulphide is a highly volatile, colorless, explosive liquid with a disagreeable odor. It is shipped in cars and drums and is used as a rubber solvent, in rubber cements, as solvent in oil extraction and sulphur using plants, in dye plants, in ice manufacture, and as an insecticide. One of its comonest uses is in grain elevators and seed elevators for destroying weevil.
Other Liquid Chemicals
Sulphur subchloride is an amber to yellowish-red oily fuming liquid with a penetrating and irritating odor. It is shipped and stored in jugs, carboys, and drums. It is used in the production of rubber, insecticides, and textiles and in purifying sugar juices. Sulphur dichloride is a reddishbrown liquid shipped in iron drums and used for the purposes similar to the sub-chloride. In the presence of water the sulphur chloride fumes hydrolize to form acid fumes which are very irritating and dangerous. The more water used on these materials the worse the fumes. Leaking containers of the chlorides should be taken to a dump and allowed to diffuse slowly into the air.
Mercury, a metal which is a liquid at ordinary temperatures, is used in manufacture of mirrors and is found in barometers, thermometers, and many recording and control instruments used in power plants and factories. When heated mercury volatilizes forming a very poisonous vapor. Inhalation of mercury vapor in dangerous amounts is usually indicated by a feeling of fullness just back of the bridge of the nose very similar to the feeling when bumped on the nose. A person affected by mercury vapor should get into the fresh air at once and have a physician called.
Bromine is a low boiling liquid, volatilizing to give heavy reddish-brown vapors. It is shipped and stored in glass or earthenware bottles or in glass carboys as a solution in water. It is used in various chemical industries. In contact with organic matter bromine may produce a fire. The poisonous and irritating action of its vapor is similar to that of chlorine. The liquid is corrosive.
Ordinary quick lime frequently becomes hot enough upon wetting to ignite wood and similar materials. Since it is usually shipped and stored in wooden barrels or in bulk in contact with wood, it should be kept dry if possible. Hot slaking lime will cause bad burns if allowed to come into contact with the skin.
Sodium hydroxide (caustic soda or lye) and potassium hydroxide (caustic potash) behave similarly to lime. They are ordinarily shipped and stored in metal cans and drums.
Sodium and Potassium. These two metals, which are very similar chemically, decompose water upon contact with it, igniting, with explosive violence, the hydrogen which is formed. The sodium or potassium is frequently scattered over a considerable area. These metals are shipped and stored in air-tight tin cans or under kerosene in cans or bottles.
Magnesium is a very light inflammable metal being particularly dangerous in the powdered form, ft is used largely by photographers and in fireworks manufacture. When in contact with water, hydrogen is evolved, so that water must be kept away.
Aluminum and Bronze Dust. Aluminum dust forms an explosive mixture with air. Water should not be used in case of fire as it may cause an explosion. Bronze dust containing aluminum dust is dangerous. Bronze dust, however, is usually free from aluminum dust and is not considered dangerous.
Oxygen causes more rapid burning and if present in sufficient quantities may cause an explosion. In contact with organic materials it may ignite them. This same action is caused by certain compounds high in oxygen. Nitric acid has been mentioned. The chlorates and perchlorates such as sodium chlorate, sodium perchlorate, potassium chlorate, potassium perchlorate, ammonium perchlorate, barium chlorate, and zinc chlorate; the nitrates of most elements, especially sodium and potassium nitrates; and the peroxides are all likely to cause explosions in contact with alcohol, ether, and similar materials, and when heated with any organic matter. Ammonium nitrate may be exploded by detonation. The peroxides are explosive when in contact with water. Water may be used on the other oxidizing materials.
Waxes, Greases, and Similar Materials
Solid greases and waxes present less of a fire hazard than the oils but when heated may give off explosive fumes. Since the melted waxes and greases are readily scattered by water, carbon tetrachloride or the foam type of fire extinguishers are most suitable for fighting these fires. Other solid materials such as camphor, borneol camphene, rosin and napthalene give off inflammable vapors when heated.
(To be continued)