Which foam is specifically designed for use on Class B flammable or combustible liquids?

AFFF foam, or Aqueous Film Forming Foam, is specifically designed for use on Class B flammable or combustible liquids. The unique formulation of AFFF allows it to create a protective film on the surface of these liquids, which helps to smother the fire and prevent the release of flammable vapors. This is critical when dealing with incidents involving hydrocarbons, such as gasoline or oil, as it not only extinguishes flames but also reduces the chances of re-ignition.

The other foam options do not have the same specialized properties geared toward Class B materials. High expansion foam is effective in filling spaces and can be used in certain applications, but it is not specifically tailored for the gasoline and oil fires that are classified as Class B. Class A foam is designed primarily for Class A fires, which involve ordinary combustibles like wood, paper, and textiles. Wet water is a term often used to describe water that has been treated to increase its wetting properties, and while it can assist in firefighting, it does not have the same efficacy in tackling flammable liquid fires as AFFF foam does.