All current methods of assessing the quantities of toxic gases from compartment fires use some form of fire prod-uct dilution with air and do not measure the actual concen-tration in compartment fires or in smaller scale toxic gas fire simulation equipment [1]. They are effectively based on cone calorimetry methods where the material is burned under free air ventilation conditions and the fire products are collected in a large hood which has entrained dilution air as well as the fire products. The total mass flow of the mixed air and fire gases is measured and the oxygen con-centration in the mixed gases is determined. This enables the mass of oxygen consumed in the fire to be determined and from this the fire HRR can be calculated. However these conditions do not represent ventilation controlled conditions inside compartments which will result in ineffi-cient combustion and higher toxic yields. Dilution of the combustion products will result in post compartment oxidation may also result in species concentrations too small to measure reliably. There are also other difficulties associated with fire toxic species measurements such as the effects and handling of the water vapour content of the combustion products. In recent years, the wider availability of portable FTIR systems, has enabled transient, simultaneous multi-species concentration measurements. However, reliable measurements can only be achieved with suitable sampling systems that included fully heated sand insulated sampling, lines, filters and pump as well as heated FTIR gas cell. This paper discusses the principles of the operation and calibration of heated FTIR analysis. It is shown how to take the advantage of the high temperature analysis to achieve accurate measurements of raw fire toxic gases, so that post oxidation of the gases as air dilutes the products of the fire is avoided, together with loss of species by solution in condensed water in the sample lines [1].
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)