Using the correct cooking oil fire extinguisher is vital when dealing with burning oils and fats. This is particularly true in a commercial kitchen where large volumes of oil may combust.
The only type of extinguisher that should be used on burning cooking oils is a wet chemical applicance, which will be labelled Class F.
Class F fire extinguishers contain a potassium solution which binds to the oil and creates a non flammable soap to extinguish high-temperature cooking oil fires.
Cooking fires start when oil, fat, or grease reaches ignition temperature. These fires are extremely dangerous as they’re very hot and easily spreadable, given that their fuel source is burning liquids.
You should never use water on an oil fire, as this will only spread the fire further.
Wet Chemical Fire Extinguishers
Wet chemical fire extinguishers contain potassium salts, which is a potassium solution consisting of potassium acetate. This solution may also contain potassium citrate or potassium bicarbonate.
No other type of fire extinguisher should be used on a cooking oil or grease fire.
You can identify a wet chemical fire extinguisher by its yellow label, which states ‘WET CHEMICAL’ in big letters. Like most fire extinguishers, wet chemical extinguishers come in a red cylinder.
Besides Class F fires, this fire extinguisher type can also be used on Class A fires and sometimes Class B fires.
This type should not be used on Class C fires (flammable gas) or Class D fires (burning metals).
See Also: What are the Colours of Fire Extinguishers – how to identify different extinguisher types from their labels.
How do they work?
This extinguisher type works in a two-fold way. Firstly, it releases a mist to cool the flames. Secondly, it releases potassium salts, which chemically react with the burning oil.
This reaction creates a soapy layer, which cuts off the oxygen from the fire and eventually extinguishes it.
How to Put Out an Oil Fire
Using a wet chemical fire extinguisher, follow these steps to put out an oil fire:
Step 1 – Cover the flames
If the oil fire has not yet spread, covering the pot with a metal lid may be all it takes to control it. If you don’t have a lid handy, you could use a metal tray.
Step 2 – Turn off the heat source
As you cover the flames, turn off the heat source completely. If the fire has spread to the point where turning off the heat source proves too risky, skip this step.
Step 3 – Set up the fire extinguisher
Remove the safety pin from the fire extinguisher and aim the nozzle towards the oil fire. Make sure the tip of the nozzle is at least one metre away from the flames.
Step 4 – Extinguish the flames
Release the potassium solution by pulling the lever and aim to cover the flames entirely in a circular motion. You should use the entire contents of the extinguisher.
Step 5 – Provide extra ventilation
There’ll likely be a lot of smoke once you’ve extinguished the flames. To clear the air, open all windows and doors to provide extra ventilation.
At What Temperature Does Oil Catch Fire?
As much as you should know how to control an oil fire when it occurs, you should also know how to avoid an oil fire from being ignited in the first place.
Part of fire safety training in the kitchen is knowing at what point different oils become ignited.
The flash point of the main oils and flammable liquids you’ll encounter in the kitchen include:
- Butter – 148°C
- Extra virgin olive oil – 190°C
- Canola – 204°C
- Refined peanut butter – 232°C
- Vegetable oil – 204°C
- Lard – 190°C
When cooking with any of the above oils and fats, you should aim to keep the temperature well below the flash points listed above to avoid an oil fire.
How To Avoid Oil Fires
As with any fire, you should safeguard yourself and your workspace to avoid oil fires from occurring. To avoid oil fires, take these precautionary steps:-
Never leave the stove unmonitored
It’s vital to stay near the stove whenever you’re using it.
Never walk away from a stove, especially when cooking with butter, vegetable oil, olive oil, or any other type of cooking oil. Although the temperature may be at a safe level, this can change rapidly, and you always need to be on the lookout for visual cues.
The visual cues of this fire type include when the oil starts to boil and whenever smoke is produced.
Keep your cooking area clear
When cooking with oils, make sure that there are no combustible materials on either side of the cooker.
This includes things like paper towels, food packaging, recipe books, etc. Although this won’t prevent an oil fire from occurring, it will definitely help prevent it from spreading.
Additionally, you should always make sure to clean the top of the stove when not in use to remove all debris-build up. This may include spilt flammable liquids or combustible materials.
Keep the lid nearby
If the flammable liquid is contained in a cooking pot and it catches fire, putting the lid on top of the pot will extinguish the fire, as it will cut off the oxygen.
For this reason, it’s important to keep your lids nearby at all times. The fire may spread to an uncontrollable level in the time it takes you to locate the lid.
Always heat oil gradually
For safety, cooking oils need to be heated gradually. If you heat them too quickly, cooking oils may start to boil and smoke.
Always have a fire extinguisher close by
Before cooking with oil of any kind, especially in deep fat fryers, always make sure that you’ve got the appropriate fire extinguisher handy.
For those who work in kitchens, making sure that a wet chemical fire extinguisher is handy at all times should be second nature.
See Also: UK fire extinguisher colours guide – how to identify fire extinguishers by the colour coding system.
