Home fires are costly, if not deadly. According to a study by the National Fire Protection Association (NFPA), between 2012 and 2016, cooking was the leading cause of reported home fires and injuries1. Always be mindful when cooking with oils and fats. Such cooking media is combustible and produces ignitable vapors once heated. Therefore, it’s important to not become distracted or leave food unattended when cooking.
Grease fires occur when cooking media is overheated. When sufficiently heated, oils and fats boil. When overheated, they smoke and catch fire. Different cooking media has different smoke points at which the media breaks down and degrades. In general, vegetable oils have higher smoke points than animal fats2. Thus, different cooking media is appropriate for different applications.
When heating oil for deep-frying, use a heavy pot with lid. Also, use a thermometer to maintain the oil at an appropriate temperature. If the oil starts to smoke or smell unpleasant, remove it from the heat and decrease temperature. If the oil catches fire, perform the following operations:
- Cover the pot with a lid to smother the fire. Metal lids are preferred as glass lids can shatter. Leave the lid on the pot until the pot has cooled. If the lid is removed while the pot is hot, the fire can reignite.
- Turn off the heat source.
- If needed, spray the pot with a Class B dry chemical fire extinguisher. Most home kitchen extinguishers are listed for Class B fires. Manufacturers also make home kitchen extinguishers that are specifically listed to combat cooking media. Fire extinguishers must be used as listed. Otherwise, they will be ineffective.
- If the fire persists, relocate to safety and call emergency personnel (911). When leaving, close the door behind you to help contain the fire.
The following are common mistakes to avoid if the oil catches fire:
- Do not move the pot. Doing so can splash the surrounding area with burning liquid.
- Never use water to combat a grease fire. When water hits a grease fire, it vaporizes, rapidly expands, entraps grease molecules, and spreads flames violently in all directions. A similar reaction occurs when deep-frying anything frozen. Even if the oil is not on fire, it will likely find a source of ignition (burner) when escaping its container, resulting in the same hazard.
- Do not use flour or any dry powder (except baking soda) to combat a grease fire. At the proper particle size and fuel-air ratio, flour is explosive when ignited. Even baking soda is largely ineffective at extinguishing grease fires when applied by hand, as it’s difficult to provide coverage that is adequate to smother the fire. It’s much better to keep a fire extinguisher nearby.
In general, most homes fires can be avoided by being attentive and using basic preventative measures. Many grease fires can simply be smothered. If needed, it is important to keep a fire extinguisher nearby. Never exacerbate a grease fire by moving it, adding water or additional fuel. These actions can quickly make a fire unruly, and likely cause injury.
Written By: Mark R. Richards, PE
Image taken from: https://www.youtube.com/user/TheDiscoverySlowDown/videos
1 Ahrens, Marty. “Home Cooking Fires.” Home Cooking Fires, National Fire Protection Association, Nov. 2018, https://www.nfpa.org/News-and-Research/Data-research-and-tools/US-Fire-Problem/Home-Cooking-Fires.
2 “Smoke Points of Cooking Oils and Fats.” Jessica Gavin Culinary Scientist, 2 Feb. 2018, www.jessicagavin.com/smoke-points-cooking-oils/.