Which NFPA class corresponds to cooking oils?

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

Answer: (A)

Fires involving cooking oils fall under a specialized category because fats ignite and react differently than many other liquids. The extinguishing approach for fats uses a wet chemical that saponifies the fats, forming a soapy layer and cooling the surface to seal off heat and air. This specific suppression method is captured by Class K. In kitchens, Class K extinguishers are designed to handle cooking oil and fat fires, rather than the usual water or foam used for ordinary combustibles or common flammable liquids. Other classes don’t fit as well: ordinary combustibles or wood and paper are Class A, typical flammable liquids are Class B, electrical fires are Class C, and metal fires are Class D. So cooking oil fires are best addressed as Class K.