Experimental Study On Fire Suppression Effectiveness Of Water Mist With Additives

As halon fire-extinguishing agent has been obsolete product and out of use, the world beganlooking for halon substitute actively. At present, some halon substitutes have been used in thepractice, such as carbon dioxide, foam, inert gas, water mist, aerosol, heptafluoropropane and soon. Water mist which has many advantages: having no environmental pollution, using a littlewater to suppress a fire fast, small destroying nature, has been as the main substitute. But,normal water mist belongs to physical methods to extinguish a conflagration, which exists somedisadvantages under some peculiar fire circumstances. So, the world study about water mist onthe improvement of fire suppression effectiveness and the extension of application range actively.Water mist with additives has become one of the research hotspots of fire safety science,especially the development of cleaning and high-effect water-based additives.This paper, on basis of self-developed separate-out effervescent atomization system,researches the fire suppression effectiveness under different mass concentrations and heightsbetween nozzle and oil pan for normal water mist and water mist with additives in limited space.In this system, by carbon dioxide gas dissolved in water, it can separate out in the mixingchamber due to depressurizing through orifice inside the nozzle, so the bubble atomizing modeof transport of double flow medium in single tube is realized. According to the investigation, thispaper selecting sodium chloride and ammonium chloride as additive researches the firesuppression effectiveness of separate-out effervescent atomization system. Results show the firesuppression effectiveness of water mist with sodium chloride or ammonium chloride additive isgenerally better than normal water mist, and there is optimum concentration ratio andappropriate height between nozzle and oil pan. Under the optimum conditions: concentration of2%and height of0.9meter to sodium chloride, or concentration of1.5%and height of0.8meterto ammonium chloride, water mist in this system can extinguish the fire in very short time. As long as nozzle starts, the flame is extinguished instantly.In addition, this paper analyzes the chemical mechanism of water mist with sodium chlorideor ammonium chloride additive, and explans various of experimental phenomena theoretically.Results show water mist with sodium chloride additive has stronger chemical inhibition Theresearches in this paper provide theoretical and experimental help for exploring more effectiveand useful water mist fire extinguishing system.