The Performance of Aged Aqueous Foams for Mitigation of Thermal Radiation

This paper investigates the effect of aging on the performance of aqueous foams as absorbers of thermal radiation. It employs a previously developed engineering method to evaluate the performance of fire‐fighting foams exposed to high fluxes of thermal radiation (5‐40 kW/m2). A radiator cone from the ISO 5660 cone calorimeter is utilised to generate a uniform heat flux of thermal radiation on a 50mm thick aqueous foam layer. A comparison of the effect of thermal radiation on freshly‐made and aged foam in terms of the drainage, evaporation and foam‐decay characteristics is carried out. Class B fire‐fighting foams in the expansion range 5‐30 are studied. The experimental data for the aged foam reflect real‐life situations. A performance‐cost index developed previously by the authors, is applied to quantify the overall stability of aged fire‐fighting foams exposed to fluxes of thermal radiation. The index demonstrates the superior performance of fresh foams in comparison to aged foams and shows that the low expansion foam (E=5) displays the worst performance to price ratio.