What is the primary function of AFFF foam in ARFF?

What is the primary function of AFFF foam in ARFF?

• A. To blanket the fuel surface, suppress vapors, and cool the fuel to prevent reignition
• B. To neutralize the fuel by chemical reaction
• C. To extinguish electrical fires only
• D. To create a barrier between responders and the fuel

Answer: (A)

AFFF foam’s main job in ARFF is to blanket the fuel surface, quickly forming a film that covers the fuel, suppresses vapors, and cools the fuel to prevent reignition. The soap-like film floats on the fuel, separating fuel from air and dramatically reducing vapor release, which fuels a rekindling if air returns. The cooling effect absorbs heat from the fuel, slowing or stopping the ignition process and helping the foam blanket stay intact. This combination—covering the surface, reducing vapors, and cooling—is what makes AFFF effective for hydrocarbon fuel fires in aircraft incidents. Chemically neutralizing the fuel isn’t how AFFF works, it isn’t limited to electrical fires, and while foam can act as a barrier, its primary purpose is surface coverage with vapor suppression and cooling.

AFFF foam’s main job in ARFF is to blanket the fuel surface, quickly forming a film that covers the fuel, suppresses vapors, and cools the fuel to prevent reignition. The soap-like film floats on the fuel, separating fuel from air and dramatically reducing vapor release, which fuels a rekindling if air returns. The cooling effect absorbs heat from the fuel, slowing or stopping the ignition process and helping the foam blanket stay intact. This combination—covering the surface, reducing vapors, and cooling—is what makes AFFF effective for hydrocarbon fuel fires in aircraft incidents.

Chemically neutralizing the fuel isn’t how AFFF works, it isn’t limited to electrical fires, and while foam can act as a barrier, its primary purpose is surface coverage with vapor suppression and cooling.