Your Guide To Understanding Class F Fires
Posted: 16/04/2024
4 minute read
Fire extinguishers


Home > News > Your Guide To Understanding Class F Fires

Your Guide To Understanding Class F Fires

The most important thing to understand about fires is that they are caused by a combination of a fuel, heat and oxygen, and it’s the fuel that differentiates one fire from another. Rarely, then are two fires exactly the same.

Because different fuels come with their own set of dangers, it’s important to understand the type of fire you’re dealing with before you attempt to take any action to extinguish it. This month at Surrey Tech Services Ltd, we’ve written a guide to Class F fires, sometimes known as kitchen or cooking fires, to help you stay calm and collected in an emergency.

What is a Class F Fire?

A Class F fire is any fire involving cooking oils and grease, hence the reference to kitchens and cooking. 

These fires occur when the oil has ignited under extreme temperatures. The flash point for a cooking fire – or point at which they auto-ignite – is somewhere between around 315°C and 340°C. That’s extremely hot, which means any disturbance to the liquid can easily spread flames.


What fire extinguisher should I use for cooking oil?

For cooking oil fires, you need a Class F fire extinguisher, which is a wet chemical fire extinguisher. These can usually be identified by their bright yellow badge.

While your instinct may be to grab any extinguisher in an emergency, only a wet chemical unit can be used. This is because it contains a chemical potassium solution that can smother a fire without disturbing the oil or grease. 

What steps do you need to take with a Class F extinguisher? Let’s look at that part next.
Wet Chemical Fire Extinguishers - Surrey Tech Services

How do you put out a grease fire?

Infographic demonstrating the use of a wet chemical fire extinguisher for Class F fires, with steps for aiming, spraying, and fully discharging to prevent reignition | Surrey Tech Services Ltd

Whether you’re in a commercial restaurant kitchen or a warehouse canteen kitchen, you should have a wet chemical extinguisher strategically placed nearby to deal with grease and cooking oil fires. Here’s how to use a wet chemical extinguisher to put out your grease fire:

  1. Grab the wet chemical extinguisher and remove any pin or seal
  2. Take the extinguisher lance in one hand, standing well back from the fire
  3. Aim the lance high above the fire and squeeze the extinguisher handle
  4. Spray the wet chemical solution back and forth above the burning oils or grease
  5. Discharge the whole extinguisher to help minimise the risk of reignition


The wet chemical solution should create a layer on the surface of the grease, helping to seal it off from any oxygen and thereby extinguishing the flames. The oil or grease can then cool, all without risking splashing the hot mixture and causing burns or reignition.

Remember, only attempt to put out flames with an extinguisher if you feel confident and if the fire is small enough. Should the flames grow or if you don’t have the right extinguisher, always raise the alarm, evacuate the building and call 999.


How can I prevent grease fires?

Due to the heat, flames and heavy use of oil and grease, fires are always a danger in any kitchen. Therefore, it’s a good idea to put in place as many safeguards as possible — prevention of grease fires is the best cure. Here are a few golden rules to follow:

  • Don’t leave any pots or pans unattended
  • Clean up any spillage or oils and fats
  • Turn off any hobs when not in use
  • Remove pans from a hob if they begin to smoke
  • Keep flammable materials away from your hob and oven
  • Get fire training for your staff and team members
  • Get professionally commissioned wet chemical extinguishers put in place

Passive fire protection

To protect your kitchen, you need high-quality equipment from a supplier you can trust. That’s why at Surrey Tech Services Ltd, we provide wet chemical fire extinguishers for use against Class F fires. Not only will you get peace of mind that you have the right fire safety equipment, but we’ll also ensure it’s correctly commissioned by a competent person to help you fully meet your legal obligations.

Call today and ask about fire extinguishers for your business, whether you’re in hospitality, construction or manufacturing, and we’ll be happy to assist.

Surrey Tech Services provide electrical fit out and fire safety services for student accommodation

    Protect your business premises today

    Call us now on 08081 689 497 to find out more about our fire alarm design, installation and maintenance services.