Characteristics of a combustion of near stoichiometric gaseous mixtures of flammable gas - Oxidizer - Fluorinated hydrocarbon at various oxygen concentrations in the oxidizer

Because fluorinated hydrocarbons are now widely used for fire extinguishing, it is interesting to use them for explosion prevention for oxidizers with different oxygen contents. An experimental investigation of the influence of the oxygen content of the oxidizer (mixture of O2 and N2) on the characteristics of combustion of nearly stoichiometric mixtures of flammable gas (hydrogen, methane) - oxidizer - fluorinated hydrocarbon (trifluoromethane CHF3, pentafluoroethane C2HF5, perfluorobutane C4F10) was carried out. The oxygen content of the oxidizer was 15, 20.6 (air) and 25% (vol.). The dependences of the maximum explosion pressure ΔPmax, the maximum pressure rise rate upon explosion (dP/dt)max and the laminar burning velocity Sui on the concentrations of the fluorinated agents for various oxygen contents were determined using standard methodologies. It was found that influence of CHF3 on ΔPmax is rather weak, while C2HF5 and C4F10 are much more effective for the reduction of the maximum explosion pressure. For all investigated fluorinated agents, the influence of the maximum pressure rise rate on the explosion and the laminar burning velocity was very strong. A qualitative explanation of the obtained results is presented.