PECULIARITIES OF SELECTING FIRE EXTINGUISHING SYSTEMS AND USING SPRAYED WATER TO EXTINGUISH FIRES

It is shown that when selecting fire extinguishing systems, the use of expert assessments using the matrix method is effective. The parameters of the matrix are the coefficients that take into account the efficiency of the fire extinguishing system under certain conditions of its operation. Examples of choosing the matrix coefficients are given and a criterion for choosing a fire extinguishing system that takes into account its integral capabilities is defined. According to this criterion, universal fire extinguishing systems include systems with sprayed water, gas chladone and inert gas systems, and powder systems. When extinguishing Class B fires, preference should be given to spray water systems. The article provides specific features of gas chladone and inert gas and powder fire extinguishing systems that limit their use. It is noted that 80 % of fire extinguishing is carried out with the use of water, due to its unique characteristics. A comparison of fire extinguishing systems using water as an extinguishing agent is provided, from which the expediency of using sprayed water in fire extinguishing systems follows. It is noted that the main effects of extinguishing fires with sprayed water are cooling the flame, displacing oxygen from the combustion zone, diluting fuel vapours and cooling the fuel surface. The greatest effect is achieved when the sprayed water evaporates completely in the combustion zone. In this case, the volume of evaporated water increases by 1700 times. It is shown that the size of water droplets has a significant impact on the effectiveness of fire extinguishing - a decrease in water droplets causes an increase in the rate of heat extraction from the burning gas-air mixture. It is noted that the fire extinguishing time has a proportional dependence on the diameter of the sprayed water droplets. It is shown that the diameter of water droplets depends on the square of the hovering velocity. Data are presented on the size of water droplets at which a water jet is identified as finely atomised water. It is noted that water droplets with a diameter equal to (1.0÷2.0)∙10-4 provide effective extinguishing in almost all cases, and the advantages of using sprayed water relative to other extinguishing agents are introduced, which include: absolute environmental friendliness, increased fire extinguishing efficiency, cost reduction, the ability to extinguish electrical equipment under electric current, etc.