Cooking oil can catch fire when a frying pan is kept on a burning stove for a long time due to a phenomenon called the "flash point" of the oil. The flash point is the minimum temperature at which the vapors of a volatile substance, such as cooking oil, can ignite in the presence of an ignition source like an open flame or a hot surface.
Here's how it happens:
Oil Vaporization: When the frying pan is heated on the stove, the temperature of the oil gradually increases. As the oil gets hotter, it starts to vaporize, turning into a gas.
Vapor Accumulation: The vaporized oil rises from the surface of the oil in the pan, creating a layer of flammable gas just above the oil.
Ignition Source: If the stove's heat is high enough, or if there's a nearby flame or other ignition source (such as a gas leak or a spark), it can provide the energy needed to ignite the flammable oil vapors.
Flame Ignition: Once the oil vapors ignite, they produce a visible flame that can spread rapidly. This is what is commonly known as a "grease fire."
Cooking oils have different flash points depending on their type. For example, extra virgin olive oil has a higher flash point than butter or vegetable oil. Oils with lower flash points are more likely to ignite at lower temperatures.
To prevent cooking oil fires, it's essential to take some safety measures:
Temperature Control: Never leave the stove unattended, especially when there's hot oil in the pan. Adjust the heat as needed and avoid overheating the oil.
Use a Thermometer: If you're frying food, use a cooking thermometer to monitor the oil's temperature to ensure it doesn't exceed its flash point.
Keep a Lid Handy: If a small fire does occur, you can try to smother it by covering the pan with a lid. This will cut off the oxygen supply and extinguish the flames.
Use a Fire Extinguisher: Have a fire extinguisher rated for cooking oil fires in your kitchen, and know how to use it properly. Water should not be used to extinguish a grease fire, as it can cause the fire to spread.
Practice Caution: Be cautious when adding food to hot oil to avoid splatters and spills that could lead to a fire.
Remember, safety in the kitchen is crucial, and being aware of the potential risks can help prevent accidents and ensure a pleasant cooking experience.