Research of Fire Extinguishing Efficiency of Binary Mixtures of Pentafluoroethane (HFC-125) and Heptafluoropropane (HFC-227ea) with Nitrogen

Abstract

The problem of using gaseous extinguishants to eliminate fire sources is to inhibit the active radicals of the flame, but at the same time it is necessary to take into account the change in the concentration of oxygen. Therefore, the object of research was the value of the extinguishing concentrations of both individual extinguishants and binary mixtures of halocarbons and inert gases during the elimination of heptanes burning. It has been proven that when nitrogen was supplied, gaseous combustion products were diluted and the relative radiation intensity of hydroxyl radicals decreased to 80 %; on the contrary, when pentafluoroethane (HFC-125) and heptafluoropropane (HFC-227ea) were supplied, the process of chemical inhibition of the combustion reaction took place which led to a significant reduction of the burning rate and, accordingly, the intensity of radiation of hydroxyl radicals by more than 4 times. The joint action of the inert gas and the combustion inhibitor in different ratios did not exceed the intensity of the radiation of hydroxyl radicals of the flame of the inhibitor itself. However, when an inert gas was introduced, the flame was being enriched with fuel and the number of hydroxyl radicals decreased, and the additional introduction of an inhibitor led to a more effective reduction of hydroxyl radicals in the flame.