On what class of fire are CAFS most effective?

• A. Class B
• B. Class A
• C. Class C
• D. Class D

Answer: (B)

CAFS is most effective on Class A fires because the foam creates a cooling, adhesive blanket that wets and penetrates ordinary combustibles like wood and paper. The foam’s water content and expanding bubbles cool the fuel and form a surface layer that lasts longer than water alone, reducing heat transfer and preventing re-ignition while the fuel is being cooled and regained control. Porous and layered materials benefit especially, since the foam can seep in and wet deeply rather than just sitting on top. In contrast, fuels on the surface of a liquid (Class B), energized electrical fires (Class C), or metal fires (Class D) require different approaches, so CAFS doesn’t provide the same level of advantage there.