Fire Safety Science Digital Archive

For many years foams have been used to extinguish flammable liquid fires in the process industry, by the formation of a layer or blanket over the burning surface of the liquid. For this purpose, chemical or mechanical foams have been used for non water-miscible liquids such as the hydrocarbons, having a fire point up to about 100 C, and special "all-purpose" foams have been developed to extend the use of foam to water-miscible liquids such as the alcohols. Other specially fortified foams have been developed for use on difficult fuels such as rocket propellants. Recently, "light water" foam has been developed in the United States as a potential replacement for the traditional chemical and protein-based foams. The development of medium and high-expansion synthetic foams has extended the use of foams from liquid to solid fires, and in its high-expansion form, this type of foam is also used for dealing with fires in volumes, as well as on surfaces. This paper gives an account of both the traditional and modern uses of foam in fire extinction, and of the equipment used for its generation and application. It endeavours to show what is the essential good practice in each application.