Additive influence on maximum experimental safe gap of ethylene-air mixtures

The maximum experimental safe gap (MESG) of ethylene-air mixtures diluted with inert gas (argon, nitrogen or carbon dioxide) were measured at variable inert mole fractions (0-0.4) and variable initial pressures (0.25-1.50 bar). The dependence of the maximum experimental safe gap on the total initial pressure, equivalence ratio and amount and nature of inert additive is discussed. The experimental maximum safe gaps were compared with MESG calculated from experimental quenching distances or from minimum ignition currents. For mixtures with constant composition the coefficients of MESG dependence on pressure were reported. The empirical correlation between MESG and the minimum ignition currents recommended in literature was reexamined using data measured for inert-diluted ethylene-air mixtures at various initial pressures. The results, especially from the range of pressures different from ambient, represent a useful characterization of inert-diluted ethylene-air mixtures, ready to be used for safety recommendations.