Fire Safety Science Digital Archive

Reduced oxygen concentration environment by diluting with nitrogen (N2) is expected as one of the alternative fire prevention and extinguishing technologies. To ensure the fire safety under reduced oxygen concentration, it is necessary to explore the carbon monoxide (CO) production because CO is known as a major cause of fatalities in compartment fire. To reveal the CO production in gaseous and liquid combustion under reduced oxygen concentration, the CO yield under oxygen-reduced condition was investigated experimentally using a cup burner. CH4 and CH3OH were used as fuels and supplied through the inner cup. Mixtures consisting of oxidizer (O2) and fire extinguishing agent (N2) were issued through the outer chimney. The relative percentages of O2/N2 were varied, maintaining the total flow rate of O2 + N2 constant. The CO concentration in the post-combustion mixture was measured as a function of the oxygen concentration. In the case of CH4 flame, the CO concentration was increased with decreasing O2 concentration. In contrast, in the case of CH3OH, the CO concentration was decreased with decreasing O2 concentration. The results show that the influence of the oxygen concentration on the CO production yield in liquid combustion is apparently different from that of gaseous combustion.