Which extinguishing agent is approved for use in a Class K system?

• A. Dry chemical
• B. Wet chemical
• C. Water
• D. Foam

Answer: (B)

The main idea is that Class K fires involve cooking fats and oils, which behave very differently from other liquids. The only extinguishing agent that is specifically designed for these fats is a wet chemical agent. It contains a potassium acetate-based formula that reacts with fats to saponify them, turning the oil into a soapy layer. This layer coats the surfaces, cools the fuel, and creates a barrier that prevents reignition by keeping air away from the oil.

Dry chemical, water, and foam don’t provide this fat-specific chemical reaction and cooling/smothering effect. Water can cause the hot oil to splatter and spread the fire, foam isn’t optimized for cooking-oil fires, and dry chemical is not approved for Class K use and can leave residues that complicate cleanup and re-ignition risk.

So, the wet chemical agent is the correct choice for Class K systems.