Which class should be used for a deep fat fryer?

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

Answer: (D)

Fires involving cooking fats and oils require an extinguishing method that handles the high heat and the oily fuel without splattering or spreading the fire. A kitchen-specific Class K extinguisher is designed for this scenario. It uses a wet chemical agent that reacts with fats and oils to saponify them—turning the oil into a soapy layer that cools and creates a barrier between the fuel and the heat, smothering the fire. This makes it the best choice for a deep fat fryer. Fires involving ordinary combustibles like wood or paper are better addressed by extinguishers for those fuels, and fires involving flammable liquids such as gasoline are handled with agents intended for liquids; electrical fires require nonconductive approaches. None of those are optimized for cooking oil fires in a kitchen, which is why Class K is the correct choice.