Some limiting oxygen concentrations for diffusion flames in air diluted with nitrogen

Abstract Fuels have been burned at the surface of a porous hemispherical burner of stainless steel, and the nitrogen concentration required to extinguish the flame has been determined. Results are given for a number of fuels in terms of the limiting oxygen index [O 2 /(O 2 + N 2 )], and it has been found that the values are close to those obtained for pre-mixed flames involving the fuel and oxygen in stoichiometric proportions Calculations of the adiabatic flame temperature for stoichiometric mixtures with limiting oxygen index indicate that the limit is primarily determined by the flame temperature.