Fire Safety Science Digital Archive

The properties required of high expansion foam, produced with inert gases from a jet engine generator are: (1) a slow drainage rate and (2) a slow rate of collapse, at temperatures above ambient. Three tests permit the performance of foaming agents to be assessed. A single film drainage test indicated unsuitable materials. Two tests using a system of foam generation similar to the full scale system were used to select the most suitable foaming agents from those not rejected by the first test. These were a test of the rate of collapse of foam in a tank measuring 3 ft 6 in x 2 ft 9 in x 2 ft 3 in, and a test of the rate of drainage of liquid from a plug of foam contained in a cylinder 12 ft long and 1 ft 8 in diameter. Of 30 foaming agents examined, ammonium lauryl sulphate was the best.