How does the wet chemical agent extinguish a fat/oil fire?

• A. It forms a water-based film that smothers the flame
• B. It saponifies fats to form a soapy, viscous layer that cools the fuel and prevents re-ignition
• C. It dissolves the fat completely into a non-flammable substance
• D. It absorbs heat by chemical reaction without water

Answer: (B)

The wet chemical extinguishing action hinges on saponification. When the agent contacts the fat or oil, it reacts with the fats to form potassium soaps, creating a thick, soapy, viscous layer on the surface. This layer cools the oil by absorbing heat and blankets the fuel, separating it from the air and preventing vapors from feeding the flame—so ignition cannot easily continue once the surface is covered. This mechanism is distinct from simply trying to form a water film or dissolving the fat, and it better explains why the extinguishing effect comes from the soapy layer that cools and prevents re-ignition.