Which statement about AFFF benefits is true?

• A. It increases fuel vapors.
• B. It seals fuel vapors, provides cooling, separates combustibles, and resists breakdown from other chemical agents.
• C. It only creates high-expansion foam.
• D. It is designed for water-only applications.

Answer: (B)

AFFF works by forming an aqueous film on the surface of hydrocarbon fuels. This film seals fuel vapors, cutting off the vapor source and helping prevent ignition. The water component provides cooling, absorbing heat and slowing the fire’s rise. The foam also helps separate the fuel from air and other combustibles, creating a barrier that makes it harder for the flame to re-ignite. In addition, AFFF formulations are designed to resist breakdown from other chemical agents present at the scene, so the protective film remains effective longer. It does more than just produce foam—the film, cooling, and vapor-sealing effects work together to suppress the fire and reduce reignition risk. It is not meant to increase vapors, it isn’t limited to high-expansion foam, and it isn’t designed for water-only applications.