Some Unresolved Fire Chemistry Problems

Abstract

Six areas of fire science are selected for discussion which involve chemistry in an important way. The areas are: rate of pyrolysis of a solid combustible; generation of toxicants in a fire; fire luminosity (radiative output) and smoke generation; fire retardation of wood and synthetics; flammability of a hot gas layer in a compartment before flashover; and chemically active extinguishing agents. In each case, highlights of knowledge and remaining unso Lved questions are touched upon, and 35 references to the recent literature are provided.

The Role Of Soot Particle Formation On The Production Of Carbon Monoxide In Fires

“…However, inclusion of soot in the measured total carbon accounts for the chemical transfer of carbon atoms, initially from fuel species to soot and finally from soot to CO and CO 2 , Therefore, subtracting the normalized slope of the total carbon curve from the normalized slope of the CO curve eliminates CO diffusion and approximates the net rate of reaction of CO. This approach yields the following expression for the 'corrected' net CO reaction rate in kmoles/rrr-s: (3) where t is the time in seconds and [CO] and [TC] are the CO and total carbon concentrations in kmoles/m". The subscripts c and m refer to corrected and measured values respectively.…”

“…In recent years, numerous investigations [1][2][3][4][5][6][7] have focussed on carbon monoxide (CO) production and emission from fires since CO is widely recognized as the most serious combustion product resulting from fires. It is recognized that the high concentrations of CO and soot that characterize typical fire situations [4,5] may be related.…”

Carbon Monoxide And Soot Emissions From Buoyant Turbulent Diffusion Flames

“…First of all, carbon monoxide and soot represent major hazards of fire environments: inhalation of carbon monoxide is a major cause of fatalities in fires, while the presence of soot obscures fire fighting efforts and increases flame spread and burning rates due to increased radiation from soot. Secondly, past studies suggest a correspondence between carbon monoxide and soot emissions [1][2][3][4][5], that has important implications concerning materials properties for improved fire safety and a better fundamental understanding of the phenomena causing these emissions. Thus, the present study of CO emissions was combined with a companion study of soot emissions for similar test conditions [6] to examine this correspondence.…”

“…Notwithstanding the state relationships, it is well known that CO is emitted from turbulent hydrocarbon/air diffusion flames [1][2][3][4][5]. One reason for this discrepancy is that state relationships usually are measured using gas chromatography having limited sensitivity so that the small CO concentrations of emissions are not resolved.…”

“…One reason for this discrepancy is that state relationships usually are measured using gas chromatography having limited sensitivity so that the small CO concentrations of emissions are not resolved. However, recognizing the association between CO and soot emissions [1] provides an explanation accounting for predictions of low CO emissions [9,10] as well. In particular, state relationships are usually measured normal to laminar flame surfaces, rather than through the flame tip, to reduce problems of sampling probe clogging with soot [7][8][9].…”