What class of fire is AFFF primarily used for?

Aqueous Film-Forming Foam (AFFF) is primarily used for Class B fires, which involve flammable liquids such as gasoline, oil, and other hydrocarbons. The effectiveness of AFFF in suppressing Class B fires stems from its ability to form a film on the surface of the burning liquid, which helps to cut off the oxygen supply, suppress vaporization, and prevent re-ignition.

This foam works by creating a barrier that coats the fuel, providing a cooling effect while simultaneously smothering the flames. It's particularly valuable in firefighting situations where rapid suppression of flammable liquid fires is critical, making it a preferred choice in both industrial and emergency response settings. The specific formulation of AFFF allows it to be effective against volatile liquids that are common in many fire scenarios classified under Class B.