Study On Anti-reflash Fire Extinguishing Agent-Superfine Ammonium Phosphate Dry Chemical

Fire extinguishing agent -ammonium phosphate dry chemical is one of substitutes for halon extinguishing agent, which can fight A,B,C fire. It not only has a broad extinguishing scope, high extinguishing efficiency, but also has a good relationship with entironment. At present, the main trend of fire extinguishing agent -ammonium phosphate dry chemical is superfine and surface modification to improve extinguishing efficiency. Silicon oil-Treated fire extinguishing agent -ammonium phosphate dry chemical can avoid sopping up, eroding, jetting and have a good deposit performance, but the hydrophobic film on the particle surface is lipophibic. Dry chemical powders jetted on oil surface would sink in oil quickly because of little cooling function of those powders, the whole oil surface would ignited again by small flame. In this paper anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical was prepared by dry process. Superfine ammonium phosphate dry powder prepared has a good surface shape and fit for preparing anti-reflash fire extinguishing agent through supersound air current pulverizer. Characteristics of anti-reflash dry powder surface such as wetting performance, surface tension, etc, were analyzed, and fluorocarbon surfactant as surface modification was used to prepare anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical. The surface characteristics, structure, and performance of superfine ammonium phosphate were analyzed. Fluorocarbon surfactants types were chosen as surface modification. The effects of fluorocarbon surfactant types and dosage, solvent types and dosage, temperature, warp time, stirring speed etc experiment parameters on anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical were studied, FC-118C was determined as optimal surface modificator. And the optimal process conditions of preparing anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical were determined through orthogonal experiment: FC-118C 2‰relative the whole powder quality, m (FC-118C) vs m(acetone) 1:5, dispersion temperature 35～40℃in dry powder, wrap temperature 120～140℃on the surface of dry powder, wrap time 120min, stirring speed 1500 r·min-1. On the optimal process conditions,anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical was prepared. The remaining rate against water reached 99%, the remaining rate against oil reached 96.8%, the fluidness 5.9s, the moisture absorption rate 1.68%, and all kinds of targets were more excellent than national standard. The powder size, particle distribution and surface shape of anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical were analyzed through the photos of scanning electron microscope and the particle diameter distribution instrument. The results showed that the powder particle size distribute is in 5μm mostly, and quantity specific surface is 5436.22 cm 2g , particle size distribution is narrow, particle shape is integrate, having no conglutination among particles, the surface film was entire relatively. In comparsion with the conventional-type dry extinguishing agent, the extinguishing efficiency experiment showed that anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical possess better fluidness, jet performance and extinguishing fire efficiency,remaining rate decrease from 4.0% to 0.71% after jetted, the time of fire extinguishing is shortened from 4 seconds to near 1 second and the effective number of extinguishing increased from 2 to 6 times, the extinguishing efficiency of anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical is about 4 times as high as that of conventional-type dry extinguishing agent. The anti-reflash performance of anti-reflash fire extinguishing agent -superfine ammonium phosphate dry chemical was compared with the conventional-type dry extinguishing agent, and the experiment showed that the conventional-type dry extinguishing agent could not float on oil surface and would sink in oil because it soaked oil, the extinguished oil surface can be ignited again; but anti-reflash fire extinguishing agent-superfine ammonium phosphate dry chemical could spread on oil surface, form a isolation layer, make oil isolate from gas and the extinguished oil surface can not be ignited. It showed that anti-reflash fire extinguishing agent -superfine ammonium phosphate dry chemical has excellent anti-reflash performance, and, especially, suite extinguishing fire in oil field, oil storeroom, gas station,refinery etc.