The wet chemical agent used in Class K extinguishers is most accurately described as:

• A. Potassium acetate-based wet chemical designed to saponify fats
• B. Dry chemical ABC powder
• C. Aqueous film-forming foam
• D. Sodium chloride water solution

Answer: (A)

In Class K fires, the extinguishing agent is a wet chemical designed specifically for cooking fats and oils. It is potassium acetate–based and reacts with fats to saponify them, turning the fatty layer into a soapy film. This soapy layer coats the oil, emulsifies it, and creates a cooling, protective film that smothers the flame and prevents reignition. This targeted mechanism—saponifying fats to form a soapy layer—is what makes this agent uniquely effective for kitchen oil fires, unlike other extinguishing agents that aren’t formulated to react with fats.