A red extinguisher on the wall is not automatically suitable for the risk in front of it. Choosing the right fire extinguisher types means considering the materials used, the layout of the premises, the people on site and how quickly they could evacuate. For a workplace, school, healthcare setting or managed property, this is a practical part of meeting fire safety responsibilities – not simply a matter of installing equipment.
Portable extinguishers are intended for tackling a very small fire only where it is safe to do so. Evacuation, raising the alarm and calling the fire and rescue service remain the priority. The right provision helps trained occupants respond in the earliest moments, without exposing themselves to unnecessary risk.
Fire extinguisher types and the fires they tackle
The most common extinguishers in UK commercial premises are water, foam, carbon dioxide (CO2), powder and wet chemical. Each is designed for particular fire risks. An extinguisher may be unsafe or ineffective on the wrong fuel, so a site-specific fire risk assessment should always inform selection.
Water extinguishers
Water extinguishers are commonly used for Class A fires involving ordinary combustible materials, such as paper, wood, textiles and furniture. They are often appropriate in offices, schools, shops and communal areas where these materials are the main foreseeable fuel load.
They must never be used on live electrical equipment, flammable liquids, cooking oils or fats. Water conducts electricity and can spread burning liquids, creating a more serious hazard. In the UK, water extinguishers are usually identified by a red label or red colour coding, although the cylinder itself is generally red under BS EN 3.
Foam extinguishers
Foam extinguishers are suitable for Class A materials and, where the extinguisher is rated for it, Class B flammable liquids such as petrol, diesel, paint and solvents. The foam forms a layer over the liquid surface, helping to suppress vapours and reduce re-ignition.
They are often found in workshops, storage areas and premises where small quantities of flammable liquids are present. Foam should not be used on chip-pan or deep-fat fryer fires, and it should not be selected for use on live electrical equipment unless the manufacturer’s specific instructions and rating permit it. Foam extinguishers are traditionally identified by a cream label.
Some organisations are also reviewing older foam products because of environmental considerations around certain firefighting foams. The suitable replacement depends on the fire risk, the extinguisher’s rating and the premises, rather than a blanket one-for-one swap.
CO2 extinguishers
CO2 extinguishers are primarily used on electrical fires and Class B flammable liquid fires. They leave no residue, which makes them a sensible option near server racks, electrical switchgear, laboratories and office equipment where powder or foam would cause extensive contamination.
Their limitations matter. CO2 provides no cooling effect, so a Class A material may re-ignite after the gas disperses. The discharge horn becomes extremely cold and must be handled correctly. In small, poorly ventilated rooms, discharge can also reduce oxygen levels, so the extinguisher should only be used where it is safe to do so. CO2 extinguishers are identified by a black label.
Powder extinguishers
Dry powder extinguishers can be highly versatile and are often rated for Class A, B and C fires, including flammable gases. Specialist powders are available for Class D fires involving combustible metals, but these are not standard multi-purpose powder extinguishers.
Powder can knock down a fire quickly, making it useful in certain external locations, vehicle areas, fuel stores and industrial environments. However, it dramatically reduces visibility, can irritate breathing, leaves significant residue and may damage sensitive equipment. For this reason, general-purpose powder is usually a poor choice in enclosed occupied spaces such as offices, care settings, schools and shared corridors. Powder extinguishers are identified by a blue label.
Wet chemical extinguishers
Wet chemical extinguishers are designed for Class F fires involving cooking oils and fats, particularly in commercial kitchens. The agent reacts with the hot oil to create a soapy layer that cools the surface and helps prevent re-ignition.
A wet chemical extinguisher should be positioned where kitchen staff can reach it without moving towards the fire. It is not a substitute for suitable fire blankets, automatic suppression systems or well-maintained extraction where those measures are needed. These extinguishers are identified by a yellow label.
Water mist and specialist extinguishers
Water mist extinguishers use fine droplets to cool the fire and can hold approvals for a range of risks, depending on the model. They may offer a useful alternative on some sites, particularly where reducing the number of extinguisher types would make training and response clearer. Their ratings vary, so procurement should be based on the exact model and its approved fire classifications.
Specialist extinguishers may also be needed for lithium-ion battery, metal or large-scale industrial risks. These hazards require careful assessment. A standard extinguisher chosen for general office use should not be assumed to control a battery thermal runaway or combustible metal fire.
Understanding fire classes in the UK
Fire classes describe the fuel involved, not the building type. Class A covers solid combustible materials. Class B covers flammable liquids. Class C covers flammable gases. Class D covers combustible metals, while Class F covers cooking oils and fats.
Electrical equipment is not a separate fire class in UK classification. The key question is whether the extinguisher is suitable for use where electrical equipment is energised. Once the power is isolated, the underlying fuel determines the fire class.
This distinction is especially relevant for facilities managers. A CO2 extinguisher beside a consumer unit may be appropriate, but it does not automatically provide suitable cover for the paper, furnishings and plastics elsewhere in the room.
Colour coding helps, but ratings decide
Modern extinguishers are mostly red, with a coloured identification panel and clear operating instructions. Common colour identifiers are cream for foam, black for CO2, blue for powder and yellow for wet chemical. Older equipment may not look identical, so labels, fire ratings and service information should always be checked.
The fire rating is a more meaningful guide than colour alone. For example, an extinguisher rated 13A is tested to tackle a larger Class A fire than one rated 8A. A competent provider can assess the required coverage and select equipment that is proportionate to the risk rather than simply supplying the largest possible units.
Selecting extinguishers for your premises
Under the Regulatory Reform (Fire Safety) Order 2005 in England and Wales, the responsible person must take general fire precautions appropriate to the premises and the risks. Suitable firefighting equipment forms part of those precautions. Scotland and Northern Ireland operate under different fire safety legislation, but the same practical principle applies: extinguisher provision must be based on a suitable assessment of the premises.
A fire risk assessment should consider the activities carried out on site, ignition sources, combustible materials, people at risk, escape routes and any areas with specialist hazards. A small office may require water or water-mist provision for Class A risks alongside CO2 near electrical equipment. A commercial kitchen needs arrangements specifically suited to cooking oils. A maintenance workshop may require foam, powder or specialist equipment depending on the materials used and whether the space is enclosed.
Positioning is just as important as type. Extinguishers should be visible, accessible, protected from damage and located on escape routes or near the relevant hazard, without requiring someone to move towards the fire. Staff should know that they should only attempt to use an extinguisher if they have been trained, the fire is small, they have a clear escape route and doing so does not delay evacuation.
Servicing keeps equipment ready
An extinguisher is only useful if it will operate when needed. Damage, corrosion, missing pins, pressure loss, obstructed access and outdated servicing can all compromise it. Regular inspection and maintenance in line with the relevant British Standard, commonly BS 5306-3 for servicing, helps keep equipment in serviceable condition.
Visual checks by site staff are useful between formal visits, particularly in busy shared premises. Look for missing extinguishers, broken tamper seals, blocked access, obvious damage and unreadable instructions. Formal servicing should be carried out by a competent person who can identify faults, confirm suitability and provide clear records for the responsible person.
For multi-site organisations or occupied premises, the best approach is planned provision and servicing that fits around normal operations. Janus Safety Solutions can help assess extinguisher requirements and maintain equipment with minimal disruption, giving duty holders clear evidence that this part of their fire safety arrangements is being managed properly.
The right extinguisher is the one matched to your actual risks, maintained correctly and available to people who know when not to use it. A review of your fire risk assessment and existing equipment can identify gaps before they become an emergency.