THE GLOBAL EQUIVALENCE RATIO CONCEPT AND THE FORMATION MECHANISMS OF CARBON-MONOXIDE IN ENCLOSURE FIRES

This report summarizes a large number of investigations designed to ch aracterize the formation of carbon monoxide (GO) in enclosure fires-th e most important factor in fire deaths. It includes a review analysis of the studies which form the basis for the global equivalence ratio ( GER) concept. Past and very recent (some as yet unpublished) investiga tions of CO formation in enclosure fires are reviewed. Based on the fi ndings, two completely new mechanisms for the formation of CO, in addi tion to the quenching of a fire plume by a rich upper layer, which is described by the GER concept, are identified. The first is the result of reaction between rich flame gases and air which is entrained direct ly into the upper layer of an enclosure fire. Detailed chemical-kineti c modeling studies have demonstrated that CO will be generated by thes e reactions. The second is due to the direct generation of CO during t he pyrolysis of oxygenated polymers (such as wood) which are located i n highly vitiated, high-temperature upper layers. The findings of thes e studies form the basis of an analysis that provides the guidelines f or when the use of the GER concept is appropriate for predicting CO fo rmation in enclosure fires. It is concluded that there are limited con ditions for which such use is justified. Unfortunately, these conditio ns do not include the types of fires which are responsible for the maj ority of fire deaths in building fires.