Fire Safety Science Digital Archive

The conditions have been determined under which propane diffusion flames burning around sintered metal hemispheres in an atmosphere of air and nitrogen give a high concentration of carbon monoxide in the exhaust gases. Concentration profiles have also been obtained through representative flames and across the burner housing above the burner. The results show that when the flame burns with a deficiency of oxygen, the central core of the products contains a high concentration of propane as well as propylene, ethylene, acetylene and methane. In addition, just above the top of the burner, the oxygen concentration has fallen to almost zero, and even well away from the burner it is only a tenth of its original level. It is clear that pyrolysis reactions and secondary oxidation processes occur in the region above the burner and that it is these processes which are responsible for the increased formation of carbon monoxide which occurs with flames burning in a deficiency of oxygen.