Deck General · Extinguishing Agents
Aqueous Film-Forming Foam (AFFF) extinguishes Class B fires by:
- ACooling the liquid below its flash point with cold water
- BForming an aqueous film and foam blanket that seals vapors and smothers the fire✓ Correct
- CChemically reacting with hydrocarbon fuel to neutralize it
- DDisplacing oxygen by releasing CO2 as it decomposes
Explanation
AFFF works by two complementary mechanisms: the foam blanket physically covers the liquid surface, smothering vapors; and the aqueous film that drains from the foam spreads ahead of the foam to seal unburned fuel. This makes AFFF particularly effective on large Class B (hydrocarbon liquid) fuel spill fires on flight decks and in engine rooms.
Authority: Firefighting (USCG deck topic)
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