9 Sept 2025
When a small fire starts, having the right fire extinguisher on hand can prevent a catastrophe. But with several different types available, it's easy to feel confused about which one you need. Using the wrong type of extinguisher on a fire can be ineffective and, in some cases, extremely dangerous.
This guide will demystify fire extinguishers for you. We will break down the different classes of fire, explain the main types of extinguishers, and help you understand which one to use for various situations. By the end, you'll have the knowledge to choose the right equipment for your home or workplace and use it safely.
Understanding the Classes of Fire
Before we look at the extinguishers themselves, it’s essential to understand that fires are classified based on the fuel that is burning. Fire extinguishers are labelled with letters corresponding to the classes of fire they can tackle.
Class A: Fires involving solid combustible materials like wood, paper, textiles, and plastics.
Class B: Fires involving flammable liquids such as petrol, diesel, oil, and paint.
Class C: Fires involving flammable gases like butane, propane, and methane.
Class D: Fires involving combustible metals, such as magnesium, aluminium, or sodium. These are rare outside of industrial settings.
Electrical Fires: Fires started by live electrical equipment. While not a formal class in its own right in the UK, it's a critical category. Once the electrical supply is turned off, the fire may become a Class A fire.
Class F: Fires involving cooking oils and fats, like those in deep-fat fryers.
The Main Types of Fire Extinguishers
Each type of extinguisher contains a different agent designed to combat specific fire classes. They are colour-coded for easy identification.
1. Water Extinguishers (Red)
Water extinguishers are the most common and straightforward type. They work by cooling the burning material, which extinguishes the flames.
Best for: Class A fires (wood, paper, fabrics).
Where to use: Ideal for offices, schools, and storerooms where solid combustible materials are prevalent.
DO NOT USE ON:
Flammable liquid (Class B) or cooking oil (Class F) fires: The water can cause the burning liquid to splash, spreading the fire rapidly.
Electrical fires: Water conducts electricity, creating a severe risk of electric shock.
2. Foam Extinguishers (Cream)
Foam extinguishers create a blanket over the burning fuel, which both cools it and smothers it, cutting off the oxygen supply.
Best for: Class A and Class B fires (combustible solids and flammable liquids).
Where to use: A versatile choice for workshops, garages, and petrol stations where both solid materials and flammable liquids are present.
DO NOT USE ON:
Class F fires: Though better than water, they are not designed for large cooking oil fires.
Electrical fires: The foam contains water, so it poses an electrocution risk.
3. Dry Powder Extinguishers (Blue)
Often called 'ABC' extinguishers, dry powder units are highly versatile. They work by creating a chemical barrier between the fuel and the oxygen in the air.
Best for: Class A, Class B, and Class C fires. They are also safe to use on electrical fires.
Where to use: Excellent for vehicles, commercial boiler rooms, and environments with mixed fire risks, including flammable gases.
Disadvantages: The powder can obscure vision when discharged and creates a significant mess that can be difficult to clean. It can also damage sensitive electronics. For this reason, they are not recommended for enclosed indoor spaces like offices or homes.
4. Carbon Dioxide (CO2) Extinguishers (Black)
CO2 extinguishers work by displacing oxygen and freezing the fire with an extremely cold discharge.
Best for: Electrical fires and Class B flammable liquid fires.
Where to use: Perfect for server rooms, offices with lots of electrical equipment, and mechanical workshops.
DO NOT USE ON:
Class F cooking oil fires: The powerful jet of gas can splash the burning oil.
Class A fires: The CO2 may not be sufficient to extinguish embers, and the fire could re-ignite.
Safety Note: The discharging gas is freezing and can cause cold burns if it touches the skin. Do not hold the extinguisher by its horn. In a confined space, the CO2 can displace air and cause asphyxiation. Ventilate the area immediately after use.
5. Wet Chemical Extinguishers (Yellow)
These are specialists, designed specifically for the high temperatures of cooking oil and fat fires (Class F).
Best for: Class F fires. They can also be used on Class A fires.
How it works: The wet chemical agent is discharged as a fine mist that cools the oil and reacts with it to form a soap-like film, sealing the surface and preventing re-ignition.
Where to use: Essential for commercial kitchens, canteens, and restaurants. A great addition to a domestic kitchen, especially if you use a deep-fat fryer.
Choosing the Right Extinguisher for Your Needs
Selecting the correct extinguisher depends entirely on the potential fire risks in a specific area.
For the Home: A small, multi-purpose ABC dry powder extinguisher is useful for the garage or car. For inside the house, consider a small foam extinguisher for general living areas and a dedicated wet chemical extinguisher for the kitchen. A fire blanket is also a must-have for the kitchen to smother small pan fires.
For the Office: A combination of water or foam extinguishers for general areas and CO2 extinguishers near electrical equipment and server rooms provides comprehensive coverage.
For a Workshop or Garage: Foam extinguishers are a good all-around choice. If flammable gases are also stored, an ABC powder extinguisher would be more suitable.
For a Commercial Kitchen: A wet chemical extinguisher is non-negotiable. This should be supplemented by CO2 extinguishers for electrical appliances.
How to Use a Fire Extinguisher Safely
Only attempt to use an extinguisher if the fire is small and contained, and you have a clear and safe exit route. If you are in any doubt, get out, stay out, and call 999.
If you decide to act, remember the P.A.S.S. technique:
PULL the pin at the top of the extinguisher. This breaks the tamper seal.
AIM the nozzle at the base of the fire, not the flames. Hitting the source of the fuel is key.
SQUEEZE the lever slowly and evenly to release the extinguishing agent.
SWEEP the nozzle from side to side, covering the base of the fire until it is completely out. Back away slowly, continuing to watch the area in case it re-ignites.
After any use, even a short burst, an extinguisher must be professionally recharged or replaced.
Conclusion
Fire extinguishers are powerful safety tools, but only when the right type is used correctly. Understanding the different fire classes and the corresponding extinguishers is the first step towards creating a safer environment. Take a moment to assess the risks in your home and workplace and ensure you have the appropriate equipment readily available. Knowing how to use it could make all the difference.