[en] backdraft ; under-ventilated fire ; flammability limits
[fr] diffusion criterion ; gas species
[en] Backdraft is a limited-ventilation fire phenomenon closely linked to the unburnt gases accumulated in the fire compartment just before creating an opening that allows a new supply of oxygen to enter the compartment. The aim of this article is to help understanding the influence of gas species such as hydrocarbon CmHn, water, carbon dioxide, oxygen, and nitrogen on backdraft probability. The influence of increasing the number of moles of the above gas species as well as the number of atoms of carbon, hydrogen, and oxygen in the fuel composition is analyzed. For this purpose, a diffusion flame limit criterion based on Le Chatelier's rule is used. In order to verify the obtained results, validation with 41 backdraft experiments is carried out.