How does AFFF function as an extinguishing agent?

Aqueous Film Forming Foam (AFFF) functions primarily by providing a cooling effect and forming a vapor barrier, thereby suppressing the fire effectively. The cooling effect helps to reduce the temperature of the flammable materials and the surrounding environment, decreasing the likelihood of fire spread and maintaining control over the combustion process.

The formation of a vapor barrier is critical as it prevents the escape of flammable vapors from the surface of the burning liquid. This barrier also obstructs oxygen from reaching the fire, which is essential for combustion. By cutting off the oxygen supply and cooling the fire simultaneously, AFFF ensures that the flames are effectively extinguished.

While other methods such as displacing oxygen or absorbing heat have some relevance in fire suppression, they do not encapsulate the unique dual action of AFFF that combines cooling and vapor suppression.