Fire extinguishing efficiency of the foam generated from concentrated aqueous salt solutions

Practice of application has shown that foaming agents should have predetermined properties. Introduction of special additives to composition of foaming agents allows increasing resistance of fire extinguishing foams to various negative impacts, preventing their destruction. Extinguishing fires of oil and oil products in winter time is difficult due to the low frost resistance of aqueous work solutions, which are directly used to generate the foam. Increasing of frost resistance of aqueous solutions can be reached at the expense of additives of ethylene glycol or inorganic salts. The high content of organic components makes aqueous solutions combustible therefore preference is given to inorganic salts. The most affordable salts are ammonium chloride and aluminium sulphates. If operating conditions require expeditious application of foam generated from work solutions have to be stored in any containers (for example, in fire extinguishers) then aqueous solutions should contain up to 25 % mass of inorganic salt. Dependence of spreading coefficient of aqueous salt solution flowing over the surface of heptane on concentration of foaming agent with ammonium chloride has determined in this article. According to obtained results of measurements, the value of spreading coefficient of fuel flowing over solution increases and the interfacial tension sharply decreases from 2.0 to 0.1 mN/m. The results of experiments have shown that spreading coefficient of foaming agent has the positive values for solutions with concentration of 1.0 % and higher. At such values spreading of aqueous solution over the surface of heptane become spontaneous. The results of systematic experimental studies of flame suppression process in the course of oil extinguishing, by feeding the foam into the bottom of tank, are given. Dependence of extinguishing time of the heptane on flow rate of the foam generated from aqueous salt solution is defined. It has been ascertained that addition of ammonium chloride decreases solidifying temperature of foaming agent solution and increases extinguishing time that leads to increased value of the minimum specific consumption of work solution and the optimum flow rate of foam.

огнетушащая эффективность пены, коэффициент растекания, время тушения пламени, интенсивность подачи пены, водно-солевой раствор пенообразователя, extinguishing efficiency, spreading coefficient, extinguishing time, flow rate, aqueous salt solution of foaming agent

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