What is the wet chemical extinguishing agent commonly used in Class K extinguishers?

• A. Sodium chloride
• B. Class D dry powder
• C. Aqueous film-forming foam
• D. Potassium acetate-based wet chemical agent

Answer: (D)

Potassium acetate-based wet chemical agent is used in Class K extinguishers. It works by reacting with fats and oils to saponify them, forming a soapy, protective layer that blankets the fuel, cools it rapidly, and creates a barrier between the oil and oxygen. This combination stops the flame quickly and helps prevent reignition. The other options aren’t used for Class K fires: they either target different fire types (dry powders for metals, foam for hydrocarbons) or aren’t designed for cooking-oil fires.