Which type of foam contains a surfactant that allows the foam to produce a fast spreading film?

The type of foam that contains a surfactant allowing it to produce a fast spreading film is AFFF (Aqueous Film Forming Foam). AFFF works by creating a thin film on the surface of burning fuels, which not only helps to smother the fire but also prevents the release of flammable vapors.

The surfactants in AFFF reduce the surface tension of water, enabling the foam to flow quickly over the liquid surface and effectively blanket the fuels. This rapid spreading is crucial in controlling flammable liquids fires, as it helps to establish a barrier between the fuel and the fire, which is essential for extinguishment.

Other types of foam, such as fluoroprotein foam or protein foam, do not possess the same degree of fast spreading capabilities because they are designed primarily to encapsulate the burning material rather than create a film that spreads rapidly across the surface. Alcohol-resistant foam, while effective against polar solvent fuels, does not emphasize the rapid film-forming aspect that characterizes AFFF.