Deck General · Extinguishing Agents
Which method of fire extinguishment does water primarily use when applied as a straight stream to a Class A fire?
- ASmothering by diluting oxygen
- BChain-reaction inhibition
- CCooling the burning material below its ignition temperature✓ Correct
- DFuel removal by washing combustibles away
Explanation
Water extinguishes Class A fires primarily by cooling. Its high specific heat and latent heat of vaporization absorb large amounts of thermal energy, dropping the burning material's temperature below its ignition point. A water fog or spray also has some smothering effect by displacing oxygen with steam, but cooling is the primary mechanism.
Authority: Firefighting (USCG deck topic)
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