A thermal theory for estimating the flammability limits of a mixture

Because it is difficult to treat the contributions of diluents explicitly using Le Chatelier's rule, a methodology based on thermal balance is proposed for estimating the flammability limits of a mixture. This method converts the flammability information of a mixture into a binary domain of heating/quenching potentials and, after some simple manipulations, converts them back into the flammability domain. The advantage of this conversion is the separation of the heating and quenching potential sums. The dual contribution (heating and quenching) of each species is stressed, while the simplicity of hand calculation is preserved. This method is equivalent to Le Chatelier's rule but has increased flexibility in dealing with various fuel/oxygen/diluents combinations. It will help safety engineers gain more confidence in the hazard analysis of flammable mixtures involving diluents.

► A binary thermal view of various agents (fuel/oxygen/inertant) is established in this study.
► Flammability limits are results of a competition between heating and quenching.
► A methodology is proposed to manipulate the contributions of fuel/oxygen/diluent.
► In the special cases with fuels only, this method is equivalent to Le Chatelier's rule.
► This method is still simple for hand calculations.