Combined application of fluorine containing and hydrocarbon foaming agents for extinguishing fires of oil products

Abstract

Purpose. This article describes the results of experimental and theoretical studies on possibility of combined application of fluorine containing and hydrocarbon foaming agents for extinguishing fires of oil products by supplying of low expansion foam onto the surface of burning hydrocarbon. Methods. Results of comparative tests of fire extinguishing efficiency of foams, generated from hydro¬carbon and fluorinated foam agents, are given. Tests were conducted in two modes: firstly foam was given from small height, and then - from increased height. Findings. The nature of foaming agent can be determined by measurement of the complex values of surface and interfacial tensions on a border between aqueous solution of foaming agents and oil product. Measurement of surface tension of the aqueous solutions allows determining which foaming agent is fluorine containing and which is hydrocarbon. Dependence of extinguishing time on flow rate of solution moves synchronously, almost equidistantly, to the area of minor values of flow rate. Value of extinguishing time sharply increases together with approximation of the flow rate value up to critical. The curve of dependencies of specific consumption and flow rate pass through the minimum point, which is clearly expressed despite the change of concentration of aqueous solution of the fluorine containing foaming agent. The value of mini¬mum specific consumption of the foaming solution, used to extinguish the flame of gasoline, simul¬taneously decreases. Application of mixed foaming agents, containing not more than 10 % of fluorinated components, is most appropriate. It allows providing inertness for intermix of oil product and foam, supplying onto the burning object from great height and distance. To prevent reignition it is necessary to use the mixed foaming agent, containing fluorinated components from 40 to 50 %. It provides equality of spreading coeffi-cients in the solution - fuel system and increased stability of foam. The main change of surface activity and fire extinguishing efficiency occurs when the concentration of fluorinated components reaches the level of 10 %. Thus, the value of spreading coefficient of hydrocarbon over aqueous foam-forming solution becomes zero. Values of optimum flow rate and minimum specific consumption of aqueous solution, used to extin-guish gasoline or heptane flame, sharply decrease in the same range. Research application field. The obtained results are recommended for substantiating the means of fire extinguishment of oil and oil spills. Conclusions. Results of experimental studies have shown the possibility of combined application of hydrocarbon and fluorine containing foaming agents for extinguishing fires of oil products by supplying of low expansion foam onto the surface of burning hydrocarbon.