Canola oil is a common fixture in kitchens, leading to questions about its safety. Canola oil is not considered a highly flammable liquid but is instead classified as combustible. This distinction is important because the oil requires a substantial amount of heat to ignite, unlike flammable liquids that can catch fire at room temperature. Understanding how oils burn clarifies the actual risk and provides knowledge for safe handling.
Understanding Combustible Liquids
The difference between a flammable and a combustible liquid is determined by its flash point. The flash point is the minimum temperature at which a liquid releases enough vapor to form an ignitable mixture with the air near its surface. Flammable liquids, such as gasoline, have a low flash point, typically below 100°F (37.8°C), allowing them to ignite easily under normal conditions. Combustible liquids, including most cooking oils, have a flash point at or above 100°F.
The liquid itself does not burn; fire is sustained by the combustion of the vapors released by the heated liquid. Beyond the flash point, the fire point is the temperature at which the oil produces enough vapor to sustain a flame for at least five seconds after ignition. An even higher temperature is the autoignition temperature, which is the point at which the oil ignites spontaneously without any external spark or flame source. These three temperature markers define the fire hazard level of any liquid.
Canola Oil’s High Ignition Threshold
Canola oil belongs in the combustible category because its flash point is much higher than the regulatory threshold. Refined canola oil typically has a flash point of approximately 600°F (315°C). This temperature is far above the range of normal cooking, as deep frying rarely exceeds 375°F (190°C).
The oil must be heated past its smoking point, where it begins to break down and release visible smoke, before it reaches the flash point. If the heat source is not removed, the oil will continue heating until it reaches its fire point. Eventually, it will reach its autoignition temperature, which is around 800°F (427°C). This high ignition threshold means a canola oil fire is usually the result of sustained, extreme overheating, often from a pan left unattended on a burner. The risk is manageable through vigilance and proper temperature control.
Safe Cooking Practices and Fire Response
Given the high heat required for canola oil to ignite, the most effective prevention method is to never leave heating oil unattended. Most kitchen fires involving cooking oils occur when a person is distracted or steps away from the stove while a pan is heating. Keeping the cooking area clean is also helpful, as accumulated grease and food splatters can serve as additional fuel.
Should a grease fire occur, the response must be precise due to the oil’s properties. The immediate action is to turn off the heat source if it is safe to do so. Never attempt to move the burning pan, as this risks spilling the flaming oil and spreading the fire. The most common and dangerous mistake is using water to extinguish a grease fire; water instantly vaporizes into steam when it hits the hot oil, causing the oil to violently splash and spread the flames.
The safest methods for extinguishing a grease fire focus on cutting off the oxygen supply. For a small fire, slide a tight-fitting metal lid or a cookie sheet over the pan. Baking soda can also be used for very small fires, as it releases carbon dioxide when heated, smothering the flames. For larger fires, a specialized Class K fire extinguisher is the appropriate tool, as it is designed for use on combustible cooking media.