Cooking with oil and grease is a common cause of household fires, classified as Class K fires when involving cooking oils, animal fats, or vegetable oils heated to high temperatures. While smaller oil fires may be manageable, their speed and volatility require immediate and correct action. The intense heat of burning oil requires a specific approach that differs significantly from extinguishing fires fueled by paper or wood. Understanding the proper steps is the first line of defense against a rapidly escalating kitchen disaster.
Immediate Safety Protocols and Critical Warnings
The first step upon noticing an oil or grease fire is to eliminate the heat source, if it is safe to do so. Carefully turning off the stove or burner immediately stops adding energy to the fire, which is necessary for combustion. This action may prevent a small flame from growing while you prepare to extinguish it.
Never use water to extinguish an oil fire. Oil and water are immiscible, and water sinks beneath the burning oil to the bottom of the pan. Since the oil is burning far above the 212°F boiling point of water, the water instantly flashes into steam, expanding up to 1,700 times its original size. This rapid expansion launches droplets of burning oil out of the pan, creating a spreading fireball that can cause severe burns and ignite surrounding surfaces.
Resist the urge to move the burning pan, as this can easily spill the flaming oil. Even a slight movement can cause the burning liquid to slosh over the sides, spreading the fire onto the floor or countertops. Always leave the pan in place on the burner and focus on smothering the flames directly within the cooking vessel.
Extinguishing Methods for Small Fires
Once the heat is off and the pan is stationary, a small, contained fire can be extinguished by smothering it to cut off the oxygen supply. The most effective method is to carefully slide a non-glass metal lid or a cookie sheet over the burning pan. This creates a tight seal that quickly starves the fire of oxygen. The lid should be left in place until the pan has completely cooled to prevent reignition.
Another option for small fires is to use a significant amount of baking soda (sodium bicarbonate), not baking powder or flour. When heated, baking soda releases carbon dioxide gas, which is heavier than air. This gas forms a blanket over the fire, displacing the oxygen and suffocating the flames. Salt can also be used by forming a crust that smothers the fire, but both baking soda and salt require a large quantity to completely cover the burning oil.
Smothering methods are only appropriate for fires confined to the pan where they started. If the fire has spread beyond the cooking vessel, or if the flames are igniting the kitchen hood or cabinets, the response must escalate. Attempting to use a lid on a larger fire increases the risk of injury by putting you too close to the expanding flames.
Using Fire Extinguishers and Knowing When to Evacuate
For fires too large to be safely smothered, a fire extinguisher is necessary. The most appropriate type is a Class K extinguisher, specifically designed for burning cooking oils and fats. Class K extinguishers contain a wet chemical agent that initiates saponification, reacting with the hot grease to form a soapy foam that seals the surface and cools the oil to prevent reignition. A standard dry chemical extinguisher rated Class B or ABC may also work, but Class K is the standard for cooking oil fires.
To use the extinguisher, employ the P.A.S.S. method:
- Pull the pin.
- Aim the nozzle at the base of the fire.
- Squeeze the handle.
- Sweep the spray from side to side.
Always aim for the fuel source, not the visible flames, and maintain a safe distance. If the fire spreads outside the original pan, reaches the ceiling, or if attempts to extinguish it fail, you must abandon the effort.
If the fire is spreading rapidly, or if you feel unsafe attempting to fight the flames, the priority is to evacuate the area and call 911 immediately. Once a fire has been successfully extinguished, ensure the area is well-ventilated to clear smoke or chemical residue from the extinguisher. Do not remove the lid or move the pan until it is completely cool to the touch.