Theatre Catalog (1947-48)

Gases Produced in Projection Room Fires Carbon Monoxide, Cyanide, ‘Nitrous Fumes” The Real Danger in Film Fire, Not Phosgene Whenever theatre fire safety is discussed, projection booth fires receive special emphasis. This is necessary not only because of the highly flammable nature of the materials in the projection booth, but also because a fire in the booth produces conditions somewhat different from fires in other parts of the theatre. When a material burns, it literally “goes up in smoke,” mostly in the form of fire gases. Sometimes these gases are dark, sometimes invisible; they may have unpleasant odors, or be entirely odorless; in any case, they can be deadly. Of the 10,000 persons killed annually in fires, it is estimated that about 2,800 die from “smoke poisoning,” often when the body has been untouched by the flames. LILLIAN GorboNn Safety Research Institute, Inc. While all fires may produce harmful gases, projection booth fires are a special case, because they involve film, lubricants, insulation and other materials which may not be present in the usual fire. In fact, one of the early cases of large-scale smoke poisoning occurred in a film fire. This was the famous Cleveland disaster, in 1929, when the stored x-ray film in a hospital caught fire. One hundred twenty-four persons died, chiefly from the fumes given off by the film. FIRE-PRODUCED GASES It was as a result of this fire that DASHING FOR SAFETY—and a fire extinguisher—is the projectionist’s first job when film starts to burn in a projection machine. With the hot gases of combustion rising, the exhaust fan of the booth’s ventilation system is left on to draw out as quickly as possible the noxious fumes that are formed. Fast action is demanded because of the fire’s speed and to avoid inhaling the combustion gases. research was undertaken to discover exactly what gases are produced when various materials burn. Experimental fires were set in a closed chamber, and the gases produced in this chamber were withdrawn and analyzed chemically. Properties of the gases were noted, and also their effect on the body when inhaled. Tests were run in this way on crdinary combustibles which fall in the class of cellulosic materials (wood, paper, cotton), and also on silk, wool, film, and electrical insulation containing rubber. Since all of these materials are organic (contain carbon), it was to be expected that a considerable amount of carbon would combine with the oxygen of the air to form carbon dioxide and carbon monoxide. It was found, in fact, that in each case there was rapidly developed an atmosphere which was poor in oxygen and contained toxic concentrations of carbon monoxide. Carbon monoxide is the most dangerous gas usually present in fires, since it is tasteless and odorless, and thus gives no warning of,its presence. Also its action is extremely rapid; it can kill in a matter of seconds. It was found, moreover, that, as the amount of oxygen in the air is depleted by the fire, the individual tends to breathe more rapidly, in order to inhale sufficient oxygen. Thus, even a small amount of carbon monoxide in the air can become deadly under such circumstances. When wood or paper burns there is formed, in addition to carbon dioxide and carbon monoxide, a certain amount of hydrocarbon gases, such as methane, and also some organic acids, such as acetic acid. These acids are quite irritating and may sometimes serve as a safety factor, because of their warning properties. This is also true of certain other products formed by fire, which have unpleasant odors or other effects. To quote a Bureau of Mines circular: “The actual health hazards from a non-odorous or non-irritating gas or vapor of comparatively low toxicity sometimes equal or exceed the hazard from a considerably more toxic substance, but one which possesses a marked odor or produces eye, nose, or throat irritation in advance of harmful exposure.” It is interesting to note that such common materials as wool and silk produce other very deadly gases in addition to carbon monoxide. Silk burns to give hydrogen cyanide (prussic acid); wool produces both hydrogen cyanide and hydrogen sulfide. Rubber also produces hydrogen sulfide. These gases are even more deadly than carbon monoxide, although the unpleasant odor of hydrogen sulfide, resembling rotten eggs, is a protective warning sign. It may be thought that only very small quantities of these deadly gases are produced in a fire. The fact is, however, that any of these materials burn THEATRE CATALOG 1947-48 _ -