Which of the following best describes Class K designation?

• A. It is designed for commercial kitchen oil and fat fires using wet chemical agents
• B. It is for electrical fires
• C. It is for metal fires
• D. It is for ordinary combustibles

Answer: (D)

Class K fires cover cooking oils and fats, typically in commercial kitchens, and they are fought with wet chemical extinguishing agents. These agents, usually potassium acetate, saponify the fats to form a soapy layer on the surface. That layer cools the oil, creates a barrier to heat, and smothers the fire, reducing the chance of splashing or reignition. This is why Class K is specifically tied to the kitchen-oil-and-fat hazard and the wet-chemical approach used to control it. In contrast, fires involving ordinary combustibles fall under Class A, electrical fires are Class C, and metal fires are Class D. So the statement describing oil-and-fat fires in a kitchen with a wet chemical agent best captures what Class K designation means.