Fire Safety Science Digital Archive

Major species production rates from burning polyethylene, poly (methy1 methecrylate), and ponderosa pine were measured in a two layer compartment fire environment. Reduction rates were found to be correlated by the fuel to oxygen ratio, where, the fuel supply rate is the fuel fuel volatilization rate and the oxygen supply rate is the entrainment rate of oxygen between the fuel surface and the hot/cold layer interface. The results are similar to previous results with simple gaseous and evaporating liquids and support the observation that carbon monoxide production under fuel rich conditions is greater for oxygenated hydrocarbons than hydrocarbons. Carbon monoxide yields for wood four times as large as the present results have been reported in the literature. These very large literature values were the result of sampling within the reaction zone. The present results and reanalysis of literature results obviate the need to postulate three different thermal decomposition mechanisms for wood at different fuel to oxygen ratios as has been proposed in the literature. An analysis of literature results indicates that under fuel rich conditions compartment residence times of 10-15 seconds are required for combustion to final products. Under fuel lean conditions far lower residence times are required, probably due to the enhanced mixing under these conditions.