Thermal Decomposition Of Halon Alternatives With Fluorine Under Class B Flame

The toxic gaseous products, which seriously threaten the safety of people and equipments, will be generated during fire suppression with fluorine-containing fire extinguishing agents. To explore the formation of toxic gaseous products, the thermal decomposition of five halon alternatives with fluorine, including trifluoromethane, pentafluoroethane, hexafluoropropane, heptafluoropropane and C6F-Ketone, under flame of n-heptane fuel were studied during different fire size and interaction time between agents and fire in a 1-m3 enclosure. The gaseous products were analyzed by the gas chromatography-mass spectrometry and ion chromatography.The experimental results indicate that the thermal decomposition inorganic gaseous products of these five halon alternatives with fluorine all contain hydrogen fluoride, whose concentration increase with the fire size increasing and interaction time prolonging. Under the condition of 30 seconds of interaction time, the order of the quantity of hydrogen fluoride produced at less than 2.49kW of fire size overall is C6F-Ketone > pentafluoroethane> hexafluoropropane> heptafluoropropane> trifluoromethane. At the condition of 4.79kW of fire size, the yeild of hydrogen fluoride generated at less than 20 seconds of interaction time rank overall as follows:C6F-Ketone> pentafluoroethane> heptafluoropropane> trifluoromethane> hexafluoropropane. As the fire size increases to 4.79kW and interaction time prolongs to 30 seconds, the concentration of hydrogen fluoride decomposed by heptafluoropropane increases rapidly, and the order of the concentration of hydrogen fluoride is heptafluoropropane> pentafluoroethane> C6F-Ketone> hexafluoropropane> trifluoromethane. However, when the interaction time is controlled in less than 10 seconds, the concentrations of hydrogen fluoride of these five fire extinguishing agents are low and not enough to harm people’s health.Under the condition of 4.79kW of fire size and 30 seconds of interaction time, the organic gaseous products of these five agents are all fluorocarbon, and almost all of them have an irritating effect on humans. C6F-Ketone, which is a fluorinated ketone fire extinguishing agent, has the most species of organic gaseous products than the other four agents.