THE DYNAMICS OF FLASH FIRES INVOLVING FLAMMABLE HYDROCARBON LIQUIDS

Victims of fires are sometimes discovered to have less-than-lethal lev els of carbon monoxide (GO) in the blood and no significant antemortem fire damage. Such occurrences are often linked to flash fires involvi ng volatile hydrocarbon fuels. In this study, the dynamics of hydrocar bon fuel fires are examined, and the results of full-scale room tests ignited with small (<2 L) quantities of flammable liquid are found to confirm the theoretical predictions. These tests showed that flame plu mes with temperatures of 500-975 degrees C were produced above flammab le liquids. Ignition of their vapors in a carpeted room produced a ver y short-lived flash of fire throughout the room, followed by intense f lames in a layer above the floor similar to 1 m deep, which quickly de generated to isolated pools of low flames. Combustion of hydrocarbon v apors in a room caused oxygen levels to drop below 8.5% in <100 s, whi le causing carbon dioxide (CO2) levels to increase to 12-16% whether t he door to the room was open or closed. Production of CO trailed maxim um CO2 production by 15-30 s. A victim exposed to such a fire may coll apse from extreme heat (aided by the water vapor created by the combus tion of hydrocarbons), weakened by oxygen deprivation, before CO inhal ation becomes a significant factor.