Abstract. On the basis of experimental studies it was revealed that adding of electrolyte -ammonium chloride -into solution of film-forming foaming agent leads to decrease of interfacial tension on a border with heptane, and increase of surface tension on a border with air. It is experimentally shown that dependence between specific consumption and flow rate of foaming agent passes through the minimum point that allowed defining influence of electrolyte on a value of minimum specific consumption and optimum flow rate of foam during extinguishing of a hydrocarbon flame. The structure of spreading in a foaming agent solution -hydrocarbon system defines the value of fire extin-guishing efficiency of foam decreasing together with lowering of spreading coefficient and interfacial tension.

Abstract.Depending on the size of water drops, process of fire extinguishing is focused either in a zone of combustion or on a burning liquid surface. This article considers two alternate solutions of a heat balance equation. The first solution allows us to trace decrease of temperature of a flammable liquid (FL) surface to a temperature lower than fuel flash point at which combustion is stopped. And the second solution allows us to analyze decrease of burnout rate to a negligible value at which steam-air mixture becomes nonflammable. As a result of solve of a heat balance equation it was made the following conclusion: water drops which size is equal to 100 µm will completely evaporate in a zone of combustion with extent of 1 m if the flying speed of drops is even 16 mps (acc. to Stokes v = 3 mps); whereas drops of larger size will evaporate only partially.

Purpose. The analysis of normative documents regulating the amount of foam supply intensity for extinguishing high-octane gasoline was carried out in the research. The developed technique of determining foam supply critical intensity by various methods depending on the initial heating of high-octane gasoline is described, as well as the experimental installation that allows implementing a combined foam discharge method whereby foam is simultaneously discharged both onto the surface of the combustible liquid and under the layer. Methods. The authors analyzed normative documents regulating fire extinguishment of oil and petrochemicals. The study was carried out at the experimental installation developed according to the appropriate test method. Findings. The analysis of normative documents indicated differences in the criteria for choosing foam discharge intensity for high-octane gasoline. It was decided to determine the possibility of applying increasing factors for standard values of foam discharge intensity depending on time of free fire development in a high-octane gasoline tank. The experimental installation was based on the standardized installation according to GOST R 50588, which was modernized for possible foam discharge in a combined way. Fuel is preheated to determine the heating temperature effect on foam application rate. Model foam generators with a flow rate of 1.8-2.2 g/s and pans of various diameters were used to change the intensity of foam discharge. Research application field. This technique will be used for obtaining data on determining the most effective method of extinguishing high-octane gasoline at different time intervals. The experimental installation will allow obtaining new data on choosing intensity and methods of foam discharge for modern mixed gasolines. Conclusions. The carried-out work showed the relevance of conducted research work aimed at assessing the value of foam discharge critical intensity applying various methods depending on the initial heating temperature of high-octane gasoline in the tank. To determine the target value, the experimental stand and the corresponding test procedure have been developed, the results of which will be given in further publications.

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