Choosing the right fire extinguisher can mean the difference between quickly putting out a small fire and making it worse. Different fires require different extinguishers, and using the wrong type can be dangerous or ineffective.
Do you know which fire extinguishers you need?
Let's work out what's right for your premises.
Understanding fire classes
Before we look at extinguisher types, you need to understand fire classes. Fires are categorised by the fuel that's burning:
Class A: Ordinary combustibles
Wood, paper, cardboard, textiles, plastics, most rubbish. These are the most common fires in offices, shops, and homes. They leave ash.
Class B: Flammable liquids
Petrol, diesel, oil, paint, spirits, paraffin, solvents. Not cooking oils (that's Class F). Common in workshops, garages, and industrial premises.
Class C: Flammable gases
Propane, butane, methane, natural gas, LPG. Often involves gas bottles or pipework. Turn off the gas supply if safe to do so — otherwise, let it burn in a controlled way.
Class D: Flammable metals
Magnesium, titanium, lithium, sodium. Rare outside specialist industrial settings. These fires burn extremely hot and react violently with water.
Class F: Cooking oils and fats
Vegetable oil, animal fat, lard in deep fat fryers or cooking equipment. Water or standard extinguishers make these fires explode. Common in commercial kitchens.
Electrical fires
Not officially a separate class, but electrical equipment fires need special consideration. Once electricity is isolated, the fire becomes Class A (if it's plastic/rubber burning) or another class depending on what's alight.
Never use water on electrical fires — it conducts electricity and can cause electrocution. Never use water on burning oil — it causes an explosive fireball.
Fire extinguisher types
There are five main types of portable fire extinguisher in the UK, each designed for specific fire classes:
Water extinguishers (red body, red label)
What they contain: Pressurised water, sometimes with additives.
Suitable for:
- Class A fires (wood, paper, textiles)
NOT suitable for:
- Flammable liquids (spreads the fire)
- Electrical fires (conducts electricity)
- Cooking oils (causes explosion)
- Flammable metals (violent reaction)
How they work: Cool the fuel below its ignition temperature.
Common locations: Offices, retail, schools, hotels, care homes — anywhere with primarily solid combustible materials.
Limitations: Only effective on Class A. Cheap and simple, but limited use.
Foam extinguishers (red body, cream label)
What they contain: Aqueous Film Forming Foam (AFFF).
Suitable for:
- Class A fires (wood, paper, textiles)
- Class B fires (flammable liquids)
NOT suitable for:
- Cooking oil fires (Class F)
- Flammable metals (Class D)
- Electrical fires unless dielectrically tested to 35kV (check the label)
How they work: Cool the fuel and form a blanket that smothers flames and prevents re-ignition.
Common locations: Warehouses, factories, car parks, premises with both solid and liquid fuel risks.
Advantages: Versatile, effective on two fire classes, relatively safe if accidentally used on small electrical fires (but not recommended).
CO2 extinguishers (red body, black label)
What they contain: Carbon dioxide gas under high pressure.
Suitable for:
- Electrical fires (non-conductive)
- Class B fires (flammable liquids)
NOT suitable for:
- Class A fires (no cooling effect, can re-ignite)
- Class F fires (cooking oils)
- Outdoor use in windy conditions (gas blows away)
- Confined spaces (displaces oxygen)
How they work: Smother the fire by displacing oxygen. Create a cold gas that also provides some cooling effect.
Common locations: Offices (near IT equipment), server rooms, electrical cupboards, anywhere with significant electrical risk.
Warnings:
- Discharge is very cold (can cause frostbite on skin)
- Horn becomes extremely cold during use
- Can cause asphyxiation in small, enclosed spaces
- Leaves no residue (good for sensitive equipment)
Powder extinguishers (red body, blue label)
What they contain: Dry powder (usually monoammonium phosphate or sodium bicarbonate).
Suitable for:
- Class A fires (wood, paper)
- Class B fires (flammable liquids)
- Class C fires (flammable gases)
- Some are suitable for electrical fires
- Specialist powders available for Class D (metal fires)
NOT suitable for:
- Cooking oil fires (doesn't cool enough, can re-ignite)
- Enclosed spaces indoors (powder is difficult to breathe, reduces visibility)
How they work: Create a barrier between fuel and oxygen, and interfere with the chemical reaction of fire.
Common locations: Vehicles, outdoor areas, workshops with mixed risks, premises with gas equipment.
Limitations:
- Very messy (powder gets everywhere and is hard to clean)
- Poor visibility during use (dangerous indoors)
- No cooling effect (fires can re-ignite)
- Generally being phased out indoors in favour of foam or CO2
Wet chemical extinguishers (red body, yellow label)
What they contain: Potassium acetate or potassium citrate solution.
Suitable for:
- Class F fires (cooking oils and fats)
- Class A fires (also effective on ordinary combustibles)
NOT suitable for:
- Flammable liquids (Class B)
- Electrical fires (conductive)
- Flammable metals
How they work: Create a soapy layer (saponification) that seals the surface of burning oil and cools it below ignition temperature.
Common locations: Commercial kitchens, staff kitchens, anywhere with deep fat fryers or large-scale cooking.
Important: These are essential for any premises with commercial cooking equipment involving oil or fat. Fire blankets alone are not sufficient for deep fat fryers.
If you have a commercial kitchen or deep fat fryer, a wet chemical extinguisher is not optional — it's essential. Using water, foam, or CO2 on burning oil can cause a violent explosion.
Fire extinguisher colour coding
All fire extinguishers in the UK must be predominantly red (to aid visibility in emergencies). A colour-coded label or band indicates the type:
| Extinguisher Type | Body Colour | Label/Band Colour |
|---|---|---|
| Water | Red | Red |
| Foam | Red | Cream |
| CO2 | Red | Black |
| Powder | Red | Blue |
| Wet Chemical | Red | Yellow |
Older extinguishers (pre-1997) may be entirely colour-coded (blue for powder, black for CO2, etc.). These are still legal if properly maintained, but when replacing them, you must use the new red-body-with-label standard.
In an emergency, you need to identify the right extinguisher instantly. The colour-coded band must face outward and be clearly visible.
Which extinguisher for which fire
This comparison table shows which extinguishers are effective against each fire class:
Fire Extinguisher Effectiveness by Fire Class
| Type | Class A (Wood, Paper) | Class B (Liquids) | Class C (Gases) | Class D (Metals) | Class F (Cooking Oil) | Electrical |
|---|---|---|---|---|---|---|
| Water | ✓ Excellent | ✗ Spreads fire | ✗ Ineffective | ✗ Dangerous | ✗ Explosion risk | ✗ Electrocution risk |
| Foam | ✓ Excellent | ✓ Excellent | ✗ Ineffective | ✗ Dangerous | ✗ Can worsen | △ Only if rated 35kV |
| CO2 | △ Can re-ignite | ✓ Good | △ Turn off gas first | ✗ Ineffective | ✗ Ineffective | ✓ Excellent |
| Powder | ✓ Good | ✓ Good | ✓ Good | ✓ Specialist powder | ✗ Can re-ignite | ✓ Good |
| Wet Chemical | ✓ Good | ✗ Ineffective | ✗ Ineffective | ✗ Dangerous | ✓ Excellent | ✗ Conductive |
Choose the right extinguisher for the fire type. ✓ = effective, ✗ = do not use, △ = use with caution.
Practical guidance for choosing extinguishers
Standard office or retail:
- Water or foam for general areas (Class A)
- CO2 near IT equipment, server rooms, and electrical panels
Workshop or warehouse:
- Foam (covers both Class A and B)
- CO2 for electrical risks
Commercial kitchen:
- Wet chemical (essential for cooking oils)
- CO2 or foam for surrounding areas
- Fire blanket as a backup
Vehicle or outdoor area:
- Powder (versatile, works on multiple classes)
Premises with gas equipment:
- Powder extinguishers
- Ensure staff know to turn off gas supply if safe to do so
Where to position fire extinguishers
Positioning is as important as type. The wrong extinguisher in the wrong place is useless.
General principles:
-
Near fire exits — People should be able to grab an extinguisher on their way out, not have to go deeper into the building.
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Near fire risks — Place appropriate extinguishers close to the hazards they're meant to protect against (e.g., CO2 near server racks, wet chemical by fryers).
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Visible and accessible — Mount on wall brackets or stands with clear signage. Never hide them behind doors, furniture, or boxes.
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Maximum travel distance:
- Low risk premises: 30 metres to nearest extinguisher
- Normal risk premises: 25 metres
- High risk premises: 15 metres or less
-
Consistent height — Carrying handle should typically be 1 metre from the floor (accessibility considerations may require lower positioning in some areas).
-
Appropriate capacity — Larger premises or higher risks need more extinguishers or larger sizes.
Signage
Every extinguisher must have:
- A location sign (usually above it) with the fire safety sign "Fire Extinguisher" (white pictogram on red background)
- Clear pictorial guidance on the extinguisher itself showing which fire classes it's suitable for
- Instructions for use
In large or complex premises, consider floor plans showing extinguisher locations. This helps during your fire risk assessment and makes briefing new staff easier.
Servicing requirements
Fire extinguishers are safety-critical equipment. A poorly maintained extinguisher might not work when you need it.
Annual servicing (basic service)
Requirement: Every extinguisher must be inspected and serviced by a competent person at least once per year.
What's involved:
- Check for physical damage, corrosion, or leakage
- Verify pressure gauge (if fitted) shows correct pressure
- Check hose and nozzle are clear and undamaged
- Ensure operating instructions are legible
- Check pin and tamper seal are intact
- Test discharge mechanism
- Confirm extinguisher is still within its service life
- Apply a service label with date and technician details
Standard: BS 5306-3:2017
Who can do it: A competent person — typically a technician from a fire safety equipment company. This is not usually a DIY task.
Cost: Typically £10-30 per extinguisher depending on type and service contract.
Extended servicing (5 years)
Requirement: More detailed inspection and testing every 5 years (or sometimes 10 years, depending on extinguisher type).
What's involved:
- Full discharge and refill
- Internal inspection
- Hydrostatic pressure testing (if required)
- Replace components as needed
- Re-commission and seal
In-house monthly checks
Between annual services, you (or your staff) should check:
- Extinguisher is in its designated location
- Access is not blocked
- Pressure gauge (if fitted) shows correct range
- No obvious physical damage
- Pin and tamper seal are intact
Keep a log of these checks as part of your fire safety records.
Fire Extinguisher Maintenance Schedule
Check extinguishers are present, undamaged, and accessible
Full inspection and service by competent technician
Discharge, internal inspection, refill, and pressure test
If used, damaged, or fails inspection
If an extinguisher is used — even partially — it must be professionally refilled or replaced immediately. A half-empty extinguisher is not reliable in an emergency.
Training requirements
Having fire extinguishers is not enough. Your staff need to know how to use them safely.
Legal requirement
The Regulatory Reform (Fire Safety) Order 2005 requires that you provide:
- Instruction and training to employees on fire safety, including the use of fire-fighting equipment
What training should cover
Basic fire safety training for all staff:
- Location of fire extinguishers and other equipment
- Which extinguisher to use on which type of fire
- When to fight a fire and when to evacuate
- How to raise the alarm
- Emergency evacuation procedures
Practical extinguisher training (recommended for designated staff):
- Hands-on use of extinguishers (ideally with a live fire trainer)
- The PASS technique:
- Pull the pin
- Aim at the base of the fire
- Squeeze the handle
- Sweep from side to side
- How to assess if a fire is safe to tackle (never risk your safety)
How often?
- Induction training — All new employees should receive fire safety training as part of their induction.
- Refresher training — At least annually, or when there are significant changes to premises or procedures.
- Practical training — Not everyone needs hands-on extinguisher training, but designated fire wardens or key staff should practice at least every 1-2 years.
Emphasise to staff: only tackle a fire if it's small, you have the right extinguisher, you've raised the alarm, and you have a clear escape route. Personal safety always comes first.
When extinguishers are required vs optional
You MUST provide fire extinguishers if:
- Your fire risk assessment identifies fire risks that appropriate extinguishers could mitigate
- You have sleeping accommodation (hotels, care homes, HMOs)
- You have a commercial kitchen with cooking equipment
- Your premises have significant fire load or occupancy
- Your premises are required to have them by building regulations or fire service notice
You MAY not need extinguishers if:
- Your premises are very low risk with minimal combustibles
- The fire service has assessed and agreed they're not necessary
- You have other fire suppression systems (e.g., sprinklers, suppression systems) and the fire risk assessment confirms extinguishers aren't needed
Practical reality
In practice, almost all non-domestic premises benefit from having appropriate fire extinguishers. They're:
- Relatively inexpensive (£20-100 per unit, plus servicing)
- Can prevent a small fire becoming a large one
- Expected by fire officers, insurance companies, and enforcement authorities
Even if not strictly required by law, the absence of extinguishers when they would obviously be useful could be evidence of inadequate fire safety management.
DIY vs Professional Extinguisher Selection
Choose Yourself
- •Simple premises with obvious risks
- •Standard office or retail environment
- •You understand fire classes and extinguisher types
- •Low-risk activities only
- •No specialist equipment or processes
Get Professional Advice
Recommended- •Complex premises or processes
- •Mixed fire risks
- •Commercial kitchens or cooking
- •Sleeping accommodation
- •Flammable substances or specialist equipment
- •You're unsure which types or how many
Bottom line: For straightforward premises, you can often determine your extinguisher needs yourself using this guide and your fire risk assessment. For anything complex, uncertain, or high-risk, professional advice ensures you have the right cover.
Common mistakes with fire extinguishers
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Wrong type for the risk — Having water extinguishers in a kitchen with cooking oil, or no CO2 near electrical equipment.
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Too few extinguishers — Meeting the minimum letter of the law but leaving large areas poorly covered.
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Poor positioning — Hidden behind doors, blocked by storage, too high/low, or requiring you to go past the fire to reach them.
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No servicing — Extinguishers that haven't been serviced in years (or ever) may not work when needed.
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No training — Staff don't know where extinguishers are, which to use, or how to use them.
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Not replacing after use — A partially used extinguisher is left in place instead of being refilled or replaced.
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Ignoring damage — Dents, corrosion, missing pins, or low pressure ignored during monthly checks.
Hotel fined after guest injured by wrong extinguisher
A guest discovered a small fire in a hotel room waste bin. They used the nearest extinguisher — a water extinguisher — not realising a phone charger had started the fire. The water conducted electricity, causing an electric shock.
- ✗Water extinguisher in a bedroom with electrical items
- ✗No CO2 or foam extinguisher nearby
- ✗Guest had not been informed about fire equipment during check-in
- ✗Staff had not been trained on correct extinguisher placement
The hotel was prosecuted for inadequate fire risk assessment and fined £8,000 plus costs. They were required to reposition extinguishers throughout the building and implement comprehensive staff training.
Having extinguishers is not enough — they must be the right type for the likely fire risks in that location, and people must understand which to use.
Frequently asked questions
No. Using the wrong extinguisher can make a fire worse or cause injury. Water on electrical fires can electrocute you. Water on oil fires causes an explosion. Always check the extinguisher label and only use it on fire classes it's rated for.
Replace if: the pressure gauge shows it's not in the green zone, it's physically damaged or corroded, it's been partially discharged, it fails an annual service inspection, or it has reached the end of its service life (typically 10-20 years depending on type).
Extinguishers are rated by size and fire rating (e.g., 13A for Class A fires). A typical office might use 6-litre water or foam extinguishers, or 2kg CO2. Larger premises or higher risks need more capacity. Your fire risk assessment should determine this, or consult a fire safety professional.
Basic monthly visual checks, yes. Annual servicing and extended servicing must be done by a competent person — usually a qualified technician from a fire safety company. DIY servicing is not recommended as you could compromise the extinguisher's effectiveness.
Not legally required for domestic properties, but many people choose to have one (usually a small foam or multi-purpose extinguisher) for peace of mind, especially in kitchens or garages. Ensure everyone in the household knows how to use it safely.
ABC powder (usually monoammonium phosphate) works on Class A (solid), B (liquid), and C (gas) fires. BC powder (usually sodium bicarbonate) works only on B and C fires. ABC is more versatile but slightly more corrosive. Check the label for the specific fire classes covered.
Some types (especially larger ones) can be refilled and recharged by a specialist company. Smaller extinguishers, and those damaged or past their service life, should be replaced. Never attempt to refill an extinguisher yourself.
CO2 extinguishers are highly effective and still widely used. However, in confined spaces or where vulnerable people are present, there's a risk of asphyxiation from the CO2 gas. Some organisations choose foam or water mist extinguishers instead. This is a risk management decision based on your specific circumstances.
1. Ensure everyone is safe and the fire is out or contained. 2. Call the fire brigade if you haven't already (even if fire is out). 3. Evacuate if there's any doubt. 4. Arrange immediate refill or replacement of the extinguisher. 5. Investigate the cause and review your fire risk assessment.
Next steps
Now you understand fire extinguisher types, make sure you have the right ones:
- Review your fire risk assessment — What fire classes are present in your premises?
- Check your existing extinguishers — Right type? Right location? Recently serviced?
- Arrange annual servicing — If your extinguishers haven't been serviced in the last year, book it now.
- Train your staff — Everyone should know where extinguishers are and which to use.
Related articles:
Not sure which extinguishers you need or where to position them? A fire risk assessor can evaluate your premises and recommend the right fire safety equipment for your specific situation.