Fire Extinguishers — the five types
Grab the wrong one and you can make a fire worse, or kill yourself trying. Here’s the colour-coded cheat sheet every site manager should know by heart.
First — know your fire classes
UK fires are classified A to F by what’s burning. The extinguisher you reach for must match — get it wrong and you’ll make things dramatically worse.
- ASolids — wood, paper, textiles, rubber
- BFlammable liquids — petrol, diesel, paint thinners, oils
- CFlammable gases — LPG, acetylene, natural gas
- DCombustible metals — magnesium, sodium, lithium, aluminium dust
- EElectrical — energised equipment (rated separately, not officially a class)
- FCooking oils & fats — kitchens, canteens
The five extinguisher types
All UK extinguishers are red-bodied since 1997, with a coloured label indicating the contents. The older fully-coloured bodies are still seen in many older buildings — worth knowing both systems.
Water
Class A
Paper, wood, fabric, soft furnishings. Cheapest, simplest, most common in offices and hotels.
Never on electrical, liquid or cooking-oil fires.
Foam
Class A & B
Solids plus flammable liquids. AFFF foam forms a film that smothers fuel vapour. Workshop, forecourt, factory-floor default.
Not for electrical (conductive) or cooking oils.
Dry Powder
Class A, B, C & Electrical
The generalist. Works on almost everything including live electrics up to 1000v. Vehicles, garages, LPG stores.
Messy residue, can damage electronics. Dangerous to breathe in confined spaces.
CO2
Class B & Electrical
Displaces oxygen, suffocates the flame. Leaves no residue — server rooms, switchgear, electrical panels.
The horn gets extremely cold. Never hold by the horn — cryogenic burns. Avoid in small enclosed spaces: asphyxiation risk.
Wet Chemical
Class F (plus A)
Potassium-salt solution specifically for cooking oils. Reacts with fat to form a soap layer, smothering and cooling simultaneously.
Commercial kitchens require this by fire-risk-assessment law.
Using one safely — PASS
The international mnemonic. Takes two seconds to remember, can save your life.
When to fight — when to run
Attempt to tackle
- Smaller than a waste-paper bin
- One extinguisher away from escape route
- You know the class and have the right type
- You’re trained and confident
- Alarm raised, 999 called
Evacuate instead
- Bigger than a waste-paper bin
- Smoke filling the room
- Escape route compromised
- Unknown fuel (could be chemical)
- You’re not sure what to do
Inspection & maintenance
- Monthly visual check: by the site’s responsible person. Pressure gauge, seals intact, access clear.
- Annual service: by a BAFE-registered engineer. Service label updated, pressure tested.
- Extended service: every 5 years (10 for CO2). Internal inspection and refill.
- Replacement: typically 20 years unless a previous service requires earlier retirement.