EXTINGUISHING OF A FLAME BY DRY CHEMICAL POWDERS AND AEROSOL COMPOSITIONS

Efficiency of extinguishing means and methods is estimated by minimal consumption of fire extinguishing agent. From the theory of burning termination it is detect that for extinguishing of a flame it is enough to reduce the temperature in combustion zone down to 1000 °C that is equal to absorption of 50 % of heat released while burning in unit of time. Ways to reduce the temperature in combustion zone are considered. It is shown that regularities of flame extinguishing by dry chemical powders and aerosol compositions have much in common with mechanism of extinguishing effect of finely dispersed water. Powders have one more mechanism that impact on a flame — flame arrest effect. Material balance of a powder which forms the flame arrester volumetric grid over all surface of burning liquid is considered. The interrelation of optimum and critical intensity is revealed. It is shown that during extinguishing by various substances (liquid freon, sprayed water and powder), irrespective of the accepted suppression model, in all studied cases it is revealed an extreme dependence of specific consumption on delivery rate intensity of extinguishing substance.