What Are the Types of Fire Extinguisher? A UK Guide

Every fire extinguisher is built for specific fires. If you have the wrong extinguishers, you may be failing regulatory compliance. Worse, using the wrong extinguisher can make a fire worse. So it pays to know which extinguishers are designed for which jobs.

This guide walks through the main types of fire extinguisher used in UK premises, plus the newer lithium-ion category, and tells you which kinds of fire each one is designed to fight.

What are the different classes of fire?

Every extinguisher is designed for specific types of fire, and those types are grouped by the fuel involved.

• Class A: solid combustibles (wood, paper, textiles, plastics)
• Class B: flammable liquids (petrol, oils, paints, solvents)
• Class C: flammable gases (propane, butane, methane)
• Class D: combustible metals (magnesium, aluminium, sodium)
• Class F: cooking oils and fats
• Class L: lithium-ion cells and battery packs

What about electrical fires?

“Electrical fire” describes the source of the ignition, whereas the classes of fire describe what’s actually burning. But, of course, you need to treat a fire with an electrical ignition differently: using a water extinguisher on a class A fire with an electrical ignition, for example, is extremely dangerous.

If there is any doubt as to whether there is live electrical equipment in the vicinity of a fire, you should only use CO2 or dry powder extinguishers. Foam and water mist extinguishers that have been dielectrically tested will also be safe to use.

Class L describes a type of electrical fire, though the thing that’s burning is the battery itself. Class L is the newest addition, introduced with the publication of BS ISO 3941:2026 to reflect the growing use of lithium-ion batteries in electric vehicles, e-bikes, tools, and energy storage systems. It hasn't yet been incorporated into the BS EN 3 extinguisher rating system, so you won't see it printed as a rating on a standard extinguisher label. But you should be considering it in your fire risk assessment if lithium-ion batteries are present in your premises.

Water fire extinguishers

Suitable for: Class A fires (solid combustibles like wood, paper, and textiles)

Water extinguishers are the oldest and simplest type, marked with a red label. They contain water only, which keeps them cheap and environmentally friendly. They put fires out by soaking the burning material and cooling it enough to stop it burning (GOV.UK, Fire safety risk assessment: offices and shops).

When do I need a water fire extinguisher?

Water is a good fit for premises where those materials dominate the fire load.

• Offices where paper and furniture are the main risk
• Shops and retail environments
• Warehouses storing combustible goods
• Schools and public buildings
• Reception areas and communal spaces in larger premises

Don't use water on electrical, liquid, or metal fires. On live electrical equipment, it conducts current. On burning oil, it turns to steam and throws the oil in every direction.

See our water fire extinguisher range.

Foam fire extinguishers

Suitable for: Class A and B fires (solid combustibles and flammable liquids)

Foam is the versatile step up from water, marked with a cream label. It handles solid combustible fires and flammable liquid fires, and the foam blanket helps prevent re-ignition once the fire is out. Foam smothers the fire by cutting off the oxygen supply, and cools the burning material as its water content evaporates (GOV.UK, Fire safety risk assessment: offices and shops).

Not all foam is the same, though. Traditional AFFF foam contains PFAS chemicals, which are being phased out in the UK on environmental and health grounds. Modern fluorine-free foam does the same job without them, so if you're replacing older extinguishers, look for the fluorine-free option.

When do I need a foam fire extinguisher?

Foam suits premises with mixed Class A and Class B fire risks.

• Garages and workshops where petrol, oil, and combustible materials sit side by side
• Manufacturing environments handling paints or solvents
• Vehicle depots
• Storage sites for flammable liquids
• Mixed-use commercial premises

As a rule, foam extinguishers aren't for electrical fires. But some modern foam models are dielectrically tested and marked accordingly, which makes them safe near live electrical equipment. Check the label rather than assume.

See our foam fire extinguisher range, including our fluorine-free foam extinguishers.

CO2 fire extinguishers

Suitable for: Class B and electrical fires (flammable liquids and live electrical equipment)

CO2 extinguishers are the clean option, identified by a black label. They handle electrical fires and flammable liquid fires, and they leave no residue. That matters when the thing on fire is your server or your test equipment. CO2 works by displacing the oxygen around the fire: the gas is heavier than air, so it settles over the burning surface and suffocates the flame (GOV.UK, Fire safety risk assessment: offices and shops).

CO2 displaces oxygen for you as well as for the fire, so ventilate the space afterwards. And the horn gets extremely cold on discharge; grip the insulated handle, not the horn.

When do I need a CO2 fire extinguisher?

CO2 belongs anywhere sensitive equipment might catch fire, or anywhere the mess left by foam or powder would create a bigger problem than the fire itself.

• Server rooms and data centres
• Offices with electrical distribution boards, printers, and IT equipment
• Laboratories with sensitive instrumentation
• Retail spaces with high-value electronics

CO2 isn't right for solid combustibles on its own. It doesn't cool the material, so a paper or wood fire can re-ignite once the gas has dispersed. Pair it with water or foam where Class A cover matters.

See our CO2 fire extinguisher range.

Dry powder fire extinguishers

Suitable for: Class A, B, and C fires (solid combustibles, flammable liquids, and flammable gases), plus electrical fires up to 1000V

Dry powder covers the broadest range of fire classes: solids, flammable liquids, and flammable gases. Marked in blue, it's what you'll see on vehicles and outdoor sites where the risks vary. Powder works by smothering the fire, forming a barrier between the fuel and the oxygen it needs to burn.

There's a trade-off, though. Powder is messy, and the discharge cloud makes it very hard to see or breathe. So it's not the right choice for enclosed offices or public spaces where the powder itself would create a new problem.

When do I need a dry powder fire extinguisher?

Powder is for outdoor and vehicular use, and industrial environments where its versatility outweighs the clean-up.

• Vans, HGVs, and other commercial vehicles
• Construction sites
• Garage forecourts and fuel points
• Workshops handling multiple fuel types
• Boiler rooms and gas cylinder storage
• Plant machinery and outdoor equipment

Don't use dry powder in confined indoor spaces if you can help it. The visibility drop can be dangerous on an escape route, and the clean-up can damage electrical equipment or soft furnishings. Standard dry powder won't handle Class D metal fires. Burning magnesium, aluminium, sodium, or lithium metal needs specialist powder: M28 for most metals, and L2 for lithium metal specifically.

See our dry powder fire extinguisher range.

Wet chemical fire extinguishers

Suitable for: Class F fires (cooking oils and fats). Most models also cover Class A (solid combustibles like wood, paper, and textiles)

Wet chemical extinguishers, marked with a yellow label, are the specialist option for cooking oil fires. If you're running a commercial kitchen with deep fat fryers, this is the extinguisher you need.

The extinguisher discharges a fine spray of potassium acetate or potassium salts. On contact with hot oil, the potassium reacts with the fatty acids to form a soapy layer that seals the surface and cuts off oxygen, while the water content cools the oil below its auto-ignition temperature.

Many wet chemical extinguishers are also rated for Class A, so they can handle a paper or fabric fire in the same kitchen space. Some are dielectrically tested for use on live electrical equipment, which matters near electric cookers. Check the label to be sure.

When do I need a wet chemical fire extinguisher?

Wet chemical is essential wherever cooking oil is heated in quantity.

• Commercial kitchens with deep fat fryers
• Chip shops and takeaway kitchens
• Hotel and restaurant catering areas
• Care home and school catering kitchens
• Any premises with a large-capacity fryer

For a domestic kitchen, a fire blanket usually covers a chip pan on its own. But if you have a proper deep fat fryer at home, a wet chemical extinguisher is a sensible addition.

See our wet chemical fire extinguisher range.

Water mist fire extinguishers

Suitable for: Class A. Some models can tackle class B and F fires. Dielectrically tested models are safe near live electrical equipment.

Water mist is the newer type on the list. It contains de-ionised water only. But instead of a solid jet, the nozzle releases the water as a very fine mist. The mist has more surface area than a jet, so it cools the fire faster while displacing oxygen at the flame front. Because the water is de-ionised, models that have been dielectrically tested are safe if inadvertently sprayed near live electrical equipment up to 1000 volts.

When do I need a water mist fire extinguisher?

Water mist suits environments with mixed fire risks, especially where clean-up matters.

• Care homes and hospitals
• Schools
• Offices with a mix of paper and electrical equipment
• Homes where a single extinguisher needs to cover several risks
• Any indoor space where residue from foam or powder would be a problem

Water mist isn't a replacement for wet chemical in a commercial kitchen with a deep fat fryer, and it isn't the right choice for outdoor liquid or gas fires. Choose it for its versatility indoors, not as a catch-all.

See our full fire extinguisher range for water mist models.

Lithium-ion fire extinguishers

Suitable for: Class L fires (lithium-ion cells and battery packs)

Lithium-ion battery fires are a genuinely different problem. They burn hot, generate their own oxygen, and can re-ignite hours after they appear to be out. Conventional extinguishers are largely ineffective, and some (water, foam) can make matters worse.

Specialist lithium-ion extinguishers cool the battery cells rapidly and form a physical barrier that helps stop thermal runaway. Different manufacturers use different formulations, but the mechanism is the same

These extinguishers are why BS ISO 3941:2026 introduced Class L in the first place. But the classification is new and hasn't yet been incorporated into the BS EN 3 extinguisher rating system. So you won't see "Class L" printed as a rating on the label the way you would see 13A or 55B. What you will see is a clear statement that the unit is designed for lithium-ion battery fires.

When do I need a lithium-ion fire extinguisher?

Anywhere lithium-ion batteries are stored, charged, or used in significant quantities.

• Warehouses handling battery-powered stock
• E-bike and e-scooter storage or charging areas
• EV charging stations and vehicle depots
• Energy storage system installations
• Workshops using cordless power tools at scale
• Care homes and hospitals with large numbers of portable devices
• Offices with substantial device charging arrangements

Your existing fire extinguishers don't cover this risk. A lithium-ion unit sits alongside your other extinguishers, not in place of them.

See our lithium-ion fire extinguisher range.

What about service-free extinguishers?

Traditional fire extinguishers need an annual visit from a qualified engineer, plus a discharge and refill at year five. That adds up in cost and hassle, especially if you're managing extinguishers across multiple sites.

But service-free extinguishers use a composite construction that resists corrosion and doesn't need engineer servicing for ten years. They're available in most of the media types covered above, including water mist, foam, powder, and wet chemical. Over their lifespan they usually work out cheaper than traditional models once you factor in service visits and refills.

Think of service-free as a housing choice. Whatever media you'd normally pick, you can usually get it in a service-free version.

See our service-free fire extinguisher range.

Getting the right mix for your premises

The right extinguishers for your building come out of your fire risk assessment. That's a legal requirement under the Regulatory Reform (Fire Safety) Order 2005, and the risks in your specific environment determine which extinguishers you need and how many.

If you're unsure where to start, our team can help. Browse the full fire extinguisher range or call us on 0808 175 4375.