doi:10.3850/978-981-08-7724-8_11-01

ABSTRACT

Incapacitation from exposure to toxic fire effluent is the main cause of injury and death in fires. Toxic hazard in fires is a system property of a full-scale fire scenario, which cannot be measured directly in any small or large-scale toxicity test. It is a time-dependent phenomenon (evaluated in terms of available safe escape time, ASET) involving a sequence of different concentration and dose-related physiological and pathological toxic effects, occurring over time scales from a few seconds to several days. It also depends upon the time-concentration curves for a small set of key toxic gases and particulates, which in turn depend upon the heat release rate, effective heats of combustion and mass loss yields of toxic products, all varying with fuel composition, combustion conditions and the changing equivalence ratio during the fire. The ISO 19700 tube furnace has been developed and validated as a method for measuring effective heat of combustion and toxic product yields over a range of defined combustion conditions and equivalence ratios for input to fire engineering calculations. Existing calculation methods and models are often over simplistic in deriving pyrolysis rates using applied HRR curves and failing to vary effective heats of combustion and toxic product yields with equivalence ratio.

Keywords: Toxicity, Physiology, Equivalence ratio, Full-scale fires.

© 2011 CPD Unit, University of Leeds