The Classes of Fire and Which Extinguisher to Use
Not all fires are the same — and using the wrong extinguisher can turn a small fire into a serious one. Knowing the classes of fire and the right extinguisher for each is essential fire safety knowledge.
Fires are grouped into classes according to what is burning. Each class behaves differently and needs a particular kind of extinguishing agent. Match them correctly and you put the fire out; get it wrong and you can spread it, create dangerous reactions, or risk electrocution. Here is what every Irish workplace should understand.
The classes of fire
The European system used in Ireland divides fires as follows:
- Class A — solids such as wood, paper, cardboard, textiles and most plastics.
- Class B — flammable liquids such as petrol, diesel, oils, paints and solvents.
- Class C — flammable gases such as butane, propane and natural gas.
- Class D — combustible metals such as magnesium, aluminium swarf and lithium.
- Class F — cooking oils and fats, typically in commercial kitchens.
- Electrical fires — involving live electrical equipment. These are not given a letter, but need their own careful approach.
The first question in any fire is not "where is an extinguisher?" but "what is actually burning?" The answer decides which extinguisher is safe to use.
Matching extinguishers to fires
Extinguishers in Ireland share a red body with a coloured panel that identifies the agent inside. The main types are:
Water (red panel)
Effective on Class A fires only. Never use water on live electrical equipment or on cooking-oil fires — it is dangerous in both cases.
Foam (cream panel)
Suitable for Class A and B fires. Foam forms a blanket over burning liquids to smother them. Not for electrical or Class F fires.
Dry powder (blue panel)
A versatile agent that works on Class A, B and C fires, and some types are rated for special metal (Class D) fires. Powder can be used on some electrical fires, but it causes mess and reduces visibility, so it is generally avoided indoors where alternatives exist.
Carbon dioxide / CO₂ (black panel)
Designed for electrical fires and Class B liquids. CO₂ leaves no residue, making it ideal around electrical equipment. It does not cool well, so watch for reignition.
Wet chemical (yellow panel)
The specialist choice for Class F cooking-oil and fat fires, and also effective on Class A. Essential in any kitchen that uses deep-fat fryers.
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Why getting it right matters
The wrong agent can be worse than none at all. Water on burning oil causes a violent flare-up. Water or foam on live electrics risks electrocution. Choosing correctly is not about memorising a table under pressure — it is about having the right extinguishers in the right places and training people to recognise the fire in front of them.
Putting it into practice
In your own premises:
- Identify the fire risks in each area through your fire risk assessment.
- Provide the appropriate extinguisher types where those risks exist — for example, wet chemical near fryers and CO₂ near electrical panels.
- Sign and locate extinguishers clearly, and keep them serviced.
- Train staff to identify the class of fire and use the PASS method safely.
All of this forms part of a complete approach to workplace fire safety.
A quick reference you can actually remember
Nobody should be standing in front of a fire trying to recall a complicated table. The practical goal is to build a few simple associations in advance so the right choice feels obvious. A handful of plain-language rules carries most people through:
- Paper, wood and ordinary rubbish on fire? Water or foam.
- Burning liquid like petrol or paint? Foam, or dry powder.
- Anything electrical and live? CO₂ — never water.
- Chip pan or fryer fire? Wet chemical — and never water.
- Not sure, or the fire is spreading? Get out and call the fire service.
The safest instinct is honesty: if you are not certain you have the right extinguisher, do not gamble — evacuate and let the professionals deal with it.
Multi-purpose does not mean universal
Some extinguishers, such as dry powder, cover several classes at once, and that versatility can be reassuring. But no single extinguisher is right for everything — powder is poor for kitchen oil fires and messy indoors, and water remains dangerous on electrics and oils. The lesson is to match provision to the real risks of each area rather than relying on one type to do every job. A kitchen, a server room and a warehouse each deserve the extinguishers their specific hazards demand.
Key takeaways
- Fires are classed A (solids), B (liquids), C (gases), D (metals), F (cooking oils), plus electrical.
- Each extinguisher type carries a coloured panel: water, foam, dry powder, CO₂, wet chemical.
- Never use water on electrical or cooking-oil fires.
- Match extinguisher provision to the actual risks in each area.
- Train staff to identify the fire and choose the correct extinguisher.
Understanding the classes of fire turns a confusing wall of red cylinders into a clear set of choices. Provide the right extinguishers, place them well, and train your people — then the correct response becomes second nature.
