Study On The Pyrolysis Of The Fluorine-containing Fire Extinguishing Agents As Halon Alternatives

As the most efficient clean Halon alternatives, the fluorine-containing fire extinguishing agents produce toxic gases after being released in fires, which seriously threaten the safety of people and equipments. To explore the formation of toxic gas products and find the safer fire extinguishing agents, the pyrolysis of five new fluorine-containing fire extinguishing agents, including trifluoromethane, pentafluoroethane, hexafluoropropane, heptafluoropropane and1,1,1,2,2,4,5,5,5nonafluoro-4-trifluoromethyl pentan-3-one (C6F-ketone), were studied in a stainless tubular reactor under the temperature of500～850℃and the residence time of2-15s. The gas products were analyzed by the gas chromatography, the gas chromatography with a mass selective detection, ion chromatography and the flue gas analyzer, etc.The experimental results showed that the pyrolysis of five fluorine-containingfire extinguishing agents all produced considerable toxic products, which intensified with the temperature increasing and residence time prolonging. Meanwhile, the kinds and the concentration of products increased.The most of organic gaseous products of five agents are perfluorocarbons and considerable products were same. The toxicity of organic gaseous products was directly determined by the concentration of the perfluoroisobutylene, a very toxic product shared by all five agents, which increased as the temperature increasing and the residence time prolonging. Under the same temperature and residence time, the toxicity-order of the organic gas products of five new fluorine-containing fire extinguishing agents is C6F-ketone> trifluoromethane> heptafluoropropane> pentafluoroethane> hexafluoropropane.The carbon monoxide was the main toxic inorganic gas product of C6F-ketone and its concentration was mostly beyond10000ppm. The main toxic inorganic gas product of other four agents was hydrogen fluoride, whose concentration increased with the temperature increasing and residence time prolonging. Under the same temperature and residence time, the yield of hydrogen fluoride producing of per cubic meter reagents ranked as follow: hexafluoropropane> trifluoromethane> heptafluoropropane> pentafluoroethane.