| The pyrotechnically generated aerosol extinguishing agent,without the globalwarming potential factor and ozone depletion,was suggested as a new type of alternative Halon fire extinguishing agent.The normal pyrotechnically generated aerosol extinguishing agent is effective in extinguishing Class B fire,but have difficulty extinguishing the Class A wood-crib fire.To solve this problem,a new type of pyrotechnically generated aerosol extinguishing agent experiment,which possesses the ability to put out the Class A fire and the Class B fire,has been designed in this paper.It was concluded that P was the key to restrain the heterogeneous combustion,by summarize the wood combustion mechanism,fire extinguishment mechanism of ammonium phosphate.So the fire extinguishment mechanism of phosphorus-containing compounds have been studied through experimentally and theoretically.The homogeneous fire extinction mechanism of P2O5 was that the aerosol particles entered the root of the flame and react with free radical to destroy chain reaction.The contribution rate to extinguishing of heat-absorbing action of P2O5was 7.29%,at the same time the contribution rate of chemical extinguishing was 92.71%.PO2 produced by P2O5 in flame could deplete the OH free radical to destroy combustion chain reaction.The heterogeneous fire extinction mechanism of P2O5 was that P2O5 could dewater and carbonize the wood to reduce the inflammable gas produced from thermal cracking of wood.(HPO3)n produced from P2O5in flame was sticky.It could accumulate on the surface of the wood and formed floccules.These floccules could shield the fuel from the flame,heat and oxygen.P was applied to pyrotechnically generated aerosol extinguishing technology for the first time.The new type of aerosol forming agents contained KNO3,P,phenolic resin and basic magnesium carbonate.5 formulas were designed with different ratio.The minimum effective extinguishing mass was an index to evaluate the extinguishing ability of pyrotechnically generated aerosol extinguishing agents.The minimum effective extinguishing mass of 5formulas of new type pyrotechnically generated aerosol extinguishing agents,and one normal pyrotechnically generated aerosol extinguishing agent was studied experimentally.The best minimum effective extinguishing mass to Class A fire of new type pyrotechnically generated aerosol extinguishing agents was 25 g·m-3,and the best minimum effective extinguishing mass to Class B fire was 20 g·m-3.But the normal pyrotechnically generated aerosol extinguishing agent could only put out Class B fire.Use HSC Chemistry to simulate the combustion products from aerosol forming agents.Depending on the result of simulation,the combustion products of 5 formulas were analyzed qualitatively and quantificationally.By summarizing the result of analysis,the new type pyrotechnically generated aerosol extinguishing agent consisted of P2O5 and K3PO4.And the extinguishing efficiency of P2O5 was better than K3PO4.Three factors could influence the efficiency of fire suppression of pyrotechnically generated aerosol extinguishing agent,namely,1 the ingredients of pyrotechnically generated aerosol extinguishing agent;2 the efficiency of pyrotechnically generated aerosol extinguishing agent production;3 the burning rate of aerosol forming agent.The formula has been improved according to the research results above.An aerosol fire extinguishing apparatus was designed for the new type pyrotechnically generated aerosol extinguishing agent which could protect 1 m3and had a capacity of 200 g aerosol forming agent.According to national standard GA499.1-2010,the performance of the aerosol fire extinguishing apparatus was qualified.And the aerosol fire extinguishing apparatus was practical.This device which has been inspected and examined by China National Center for Quality Supervision and Test of Fixed Fire-Fighting Systems and Fire-resisting Building Components has become the first to be certified by the authorities as a Class A aerosol fire extinguishing product. |
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