FACTORS OF EXTINGUISHING OF THE FLAME OF COMBUSTIBLE LIQUIDS BY SPRAYED WATER

This article devoted to theoretical study of extinguishing of combustible liquids by the cooling its surface by drops of water for temperature putting out the flame. In the context of the model problem of extinguishing comes to solution of thermal conductivity equation which allows for transference of surface by burning out with opening boundary conditions. To address this problem we search the basic property of extinguishing process — relating between time of extinguishing and rate of water input. As far as extinguishing process runs over the narrow range changes of temperature of flame, burning-up rate and thermalphysic operation factors of liquid are constant and don't change. The problem is solved by the method of integral heat balance that makes it possible to reduce the integration of a partial differential equation to an ordinary differential equation. The computed approximate solution comprises only elementary functions and enables a simple interpretation of the experimental data obtained. The total calculation of water drops evaporation in a flame zone on the surface of a liquid and in its volume is considered by the water use factor which constitutes a ratio of the amount of water theoretically necessary for fire extinguishing to its actual value. From the computed solution it follows that there is a critical state when flame suppression of combustible liquids is achieved by irrigation intensity that is higher than a certain limiting value which is called a critical flow rate. By the flow rate lower than the critical one, the flame cannot be suppressed and the extinguishing time tends to infinity. The given results are applicable to the combustible liquids with a flash point above 100 °C and are not applicable to flammable liquids.