Fire extinguishers for commercial buildings

Each extinguisher type is designed around a particular class or combination of classes, identified by the coloured band on an otherwise red body under BS EN 3.

Water extinguishers (red body, no band or a red band) are effective on Class A fires only. They are not safe on flammable liquids, gases or electrical fires, and are typically placed where Class A materials are the dominant risk, such as general office and retail areas.

Foam extinguishers (cream band) cover Class A and Class B fires, making them a common choice where combustible solids and flammable liquids are both present. Some foam extinguishers are tested for use near electrical equipment, but this depends on the specific product and should not be assumed.

CO2 extinguishers (black band) are suited to Class B fires and are the standard choice near live electrical equipment, because the discharge does not conduct electricity and leaves no residue on sensitive equipment. They are common in server rooms, comms cabinets and areas with computer or electrical equipment, but are not effective on Class A fires involving deep-seated combustible materials.

Dry powder extinguishers (blue band) are rated for Class A, B and C fires and are sometimes described as multi-purpose for that reason. They are widely used in vehicle workshops, plant rooms and industrial premises with mixed risks, but powder is unsuitable for use in enclosed or occupied spaces, since discharge reduces visibility and can affect breathing, and it leaves a residue that can damage electronic equipment.

Wet chemical extinguishers (yellow band) are designed for Class F fires involving cooking oils and fats, and are also effective on Class A fires, making them the standard choice for commercial kitchens.

Specialist powder extinguishers exist for Class D metal fires, but these are only relevant to premises with that specific process risk and are not typically part of a general commercial provision.

Extinguishers need to be reachable without someone having to search for them or travel an unreasonable distance from where a fire is likely to start. Guidance commonly used for siting is a maximum travel distance of around 30 metres to a Class A extinguisher and 10 metres to one covering Class B or Class F risks, reflecting how much more quickly a flammable liquid or cooking oil fire can develop. Extinguishers are usually grouped at fire points on escape routes, close to exits and at floor level changes such as stairwells, so they are found in the same places a person would naturally be heading during an evacuation.

Mounting matters as much as location. Extinguishers are wall-bracketed or stand-mounted at a consistent height, with the carrying handle within reach for most adults, and identified with clear signage so they are visible even when partly obscured by stock, furniture or equipment. Where a building has multiple floors or distinct fire compartments, each area needs its own adequate provision rather than relying on extinguishers sited elsewhere in the building.

Extinguishers need to work the one time they are called on, which only happens if they are properly maintained in the years between. BS 5306-3 is the code of practice covering commissioning and maintenance of portable fire extinguishers, and it sets out responsibilities that sit with both the building and the servicing provider.

The responsible person, or someone appointed on their behalf, should carry out a monthly visual check: confirming each extinguisher is in its designated place, the pressure gauge (where fitted) reads correctly, the safety pin and tamper seal are intact, and there is no visible damage or corrosion. This is a quick check, not a service, and is meant to catch anything obviously wrong between the professional visits.

A competent person should service each extinguisher at least annually under BS 5306-3, checking the extinguisher internally and externally, weighing it to confirm the correct charge, testing the discharge mechanism and hose, and confirming brackets and signage are still sound. Beyond the annual service, water, foam, powder and wet chemical extinguishers typically need an extended service at five-year intervals, involving a full discharge and refill, and CO2 extinguishers require an overhaul at ten years due to the pressure vessel involved. We carry out this servicing on a planned schedule, whether or not we supplied the extinguishers originally, and issue a service report and updated labelling after each visit so the record stays current.

The classes and types covered here apply everywhere, but the mix a building needs changes with what it contains. A commercial kitchen needs wet chemical provision that an office does not, a warehouse with racking and vehicle movement needs a different layout to a retail unit with public access, and a server room needs CO2 close to the equipment it protects. Our industries and premises pages set out how extinguisher and wider fire safety provision applies to specific building types, including offices, retail, warehouses, hospitality and healthcare settings.

Whether you need extinguisher provision assessed for a new premises, an existing installation brought onto a proper servicing schedule, or units replaced following a recent inspection, send us the details of your building through our contact form and we will arrange a visit.