What is the common name for the agent used in Class K extinguishers?

• A. Water-based foam
• B. Dry chemical powder
• C. Halon systems
• D. Potassium acetate wet chemical

Answer: (D)

Class K extinguishers use a wet chemical agent designed for cooking-oil fires. The common name for this agent is potassium acetate. When heated fats and oils burn, potassium acetate saponifies the fats, forming a soapy layer that cools the oil, smothers the flame, and creates a barrier to prevent re-ignition. This targeted action makes it the preferred agent for kitchen fires, unlike water-based foam or dry chemical powders, which aren’t as effective on oils, or Halon systems, which serve different fire types.