Different materials burn in different ways. And, consequently, may require different extinguishing agents. Fires are classified according to the fuel that is burning, and fire classification systems help people identify which extinguisher is best suited to a fire emergency.
Understanding these classifications can save lives and reduce damage, particularly in the case of Class F fires.
Class F fires involve cooking oils or fats, including rapeseed, palm, vegetable, sunflower, and olive oil. These types of fire usually occur in kitchens and are extremely dangerous – they can ignite quickly, spread rapidly, and reach high temperatures that make them difficult to extinguish. However, the risk can be minimised by regular cleaning and oil-changing procedures, as well as effective extraction equipment.
What are the Common Causes of Class F Fires?
Class F fires usually occur in kitchens, igniting when oil or fat is cooking at an extremely high temperature. The most common cause is deep fat frying.
They are the source of 20% of accidental fires at home that the fire service attends to every year. And according to a Home Office study of fires in England between April 2023 and March 2024, cooking appliances were the largest ignition category for accidental dwelling fires, accounting for 44% of accidental dwelling fires.
Due to their high risk and frequency, it is advisable to know how to prevent and put out a Class F fire.
Preventing a Class F Fire
Here are some simple steps to follow to prevent a Class F fire:
- Take care not to use too much oil or fat when cooking, and never fill a pan with more than one-third of either.
- As with any type of cooking, do not leave your pots and pans unattended, and do not get distracted.
- If you wish to deep fat fry, then the safest way to do so is to use a thermostatically controlled electric fryer. This will prevent the oil from reaching a temperature that will cause it to burn.
- If you see smoke, immediately turn off the heat as the oil or cooking fat is getting too hot. Reacting quickly when you can see your food is starting to burn will prevent a fire, and save your dinner.
- Consider installing a heat detector or alarm in your kitchen. They can provide an early warning if things start to overheat. You could also place an optical smoke alarm just outside the kitchen to detect any smoke from resulting burning or cooking-related fires.
These steps should be followed when you’re cooking at home, or if you have a large kitchen as part of your business. If you have a business where a Class F fire is possible, consider training your staff in what to do. (Commercial kitchens in particular face a high risk of Class F fires.)
Essentially, you should be doing everything possible to reduce the risks associated with cooking oils and fats.
Tackling a Class F Fire
If you find yourself in a situation where you need to extinguish a Class F fire, then follow these steps:
- If it’s safe, try to turn off the heat source.
- If the fire is small, use a fire blanket to put it out. Placing one over a fire in its early stages will smother and deprive it of oxygen, thereby preventing it from growing.
- If the fire is too large for a fire blanket, then you must use a wet chemical fire extinguisher. This is the ONLY fire extinguisher suitable for Class F fires.
- Use the extinguisher in a slow, controlled, sweeping motion, and allow the wet chemical to form a soapy layer over the oil or fat. This will cool and smother the fire.
- Do NOT throw water over a Class F fire, as this will cause it to explode, swiftly spreading the fire and exponentially increasing the risk.
Because Class F fires are notoriously difficult to extinguish, the safest thing you can do is use your emergency evacuation plan to get to safety, then call the fire brigade. You should never take unnecessary risks with a Class F fire because of how dangerous they can be.
How Class F Fire Extinguishers Work
Fat fires run very hot, and standard fire extinguishers are not only unsuitable but also dangerous to use on a fat fire.
As mentioned before, Class F fires should ONLY be extinguished using a wet chemical fire extinguisher containing potassium salts. They not only cool the flames but also form a “saponification” blanket that effectively smothers the flames with a thick, soapy foam.
As with all fire extinguishers, your Class F fat fire extinguisher should be clearly marked with a British Standards Institute or BSI standard of BS EN3, a BS (BSI) Kitemark, indicating BAFE (British Approval for Fire Equipment) approval and a CE stamp. It will be bright red in colour, with a bright yellow label above the instructions panel for easy identification.
For fat fryers that hold more than three litres of oil, you must have a wet chemical fire extinguisher on your premises as a legal requirement of the Regulatory Reform (Fire Safety) Order 2005. (Larger commercial installations may also require a fixed fire system such as an “Ansul” or “Amerex” fire system)
Why Insurance Companies May Require Class F Fire Extinguishers in Kitchens
Many insurance companies insist that a wet chemical fire extinguisher is not only within easy reach of any deep fat frying equipment, but that it is also regularly maintained under contract. Fire extinguisher servicing and replacement will ensure these important extinguishers are fully operational and ready for use.
If you have any doubts about the function or condition of any fire extinguisher, you should know that it is often cheaper and easier to replace it than to service it. In a busy kitchen, fire extinguishers may be exposed to more environmental wear and tear than in other locations, and a straight replacement is quick and easy, without the worry of the costs of spare parts.
Remember, Class F fires are fast, fierce, and unforgiving. Knowing what sparks them, how to prevent them, and the right way to put them out can make all the difference – turning a potential kitchen disaster into a story you’ll be glad to tell.
