A foam fire extinguisher will be effective on which type of fires?

• A. Magnesium
• B. Aluminum
• C. Sodium
• D. Gasoline

Answer: (D)

Foam extinguishers work by forming a thick foaming blanket over the fuel, which cools the liquid and separates the fuel from the air to prevent reignition. This makes them especially effective on liquid fuel fires, like gasoline, where the foam sits on the surface and suppresses vapors. Fires involving reactive metals such as magnesium, aluminum, or sodium require different extinguishing agents, because foam isn’t effective and can even be unsafe with those metals. So gasoline fits best with what foam extinguishers are designed to handle.