What Is a Class K Fire? A Simple Guide to Kitchen Grease Fires

Class K fires are fires involving cooking oils, vegetable oils, animal fats, grease, and other cooking media used in kitchen appliances. These fires can develop quickly because the oil may remain extremely hot even after flames appear.

A simple way to remember them is this: K = Kitchen. If a fire involves hot cooking oil, fryer grease, or fat, it should be treated as a Class K fire.

What Makes Class K Fires Different?

Class K fires behave differently from fires involving paper, wood, or cloth. Hot oil can continue storing heat and may reignite if it is not properly cooled.

Water should never be poured onto a grease fire. When water contacts extremely hot oil, it can rapidly turn into steam, throw burning grease into the air, and spread flames across nearby surfaces.

Class K fires commonly occur in frying pans, deep fryers, griddles, and commercial cooking equipment.

Why the Right Extinguisher Matters

A Class K wet chemical extinguisher is specifically designed for fires involving cooking oils and fats. Its extinguishing agent helps control the flames, cool the burning oil, and reduce the risk of reignition.

Class K and Class B fires should not be confused. Class B fires involve flammable liquids such as gasoline, solvents, and oil-based paints, while Class K fires involve cooking oils and fats.

Always check the extinguisher label before use, because an ABC rating does not automatically include Class K protection.

Prevention and Safe Response

Stay near the cooking area whenever heating oil, and reduce the temperature if the oil begins to smoke. Keep towels, paper, packaging, and other flammable materials away from the stove. Clean grease buildup regularly and keep a metal lid or baking sheet nearby.

For a small pan fire, turn off the heat if it is safe and carefully slide the lid over the pan. Do not move the pan or remove the cover too soon.

Only use an extinguisher when the fire is small, contained, and you have a clear escape route. If the fire grows or smoke increases, leave immediately and call emergency services.

Reference: National Fire Protection Association (NFPA), “Cooking Safety”; U.S. Fire Administration (USFA), “Choosing and Using Fire Extinguishers.”