Fire Extinguisher Types Explained: Choosing, Siting and Maintaining Them

Why Extinguisher Choice Matters

Using the wrong extinguisher on a fire can be worse than using none at all. Water on an electrical fire risks electrocution; water on burning oil causes a violent eruption of flame. Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person for a premises must ensure appropriate fire-fighting equipment is provided, properly maintained, and that nominated staff know how to use it. Your fire risk assessment should identify what you need and where.

The Fire Classes

Extinguishers are matched to classes of fire:

• Class A: solid combustibles such as wood, paper and textiles
• Class B: flammable liquids such as petrol, solvents and paints
• Class C: flammable gases
• Class D: combustible metals
• Class F: cooking oils and fats
• Electrical: not a class in its own right, but a hazard that rules out water-based equipment unless specifically rated

The Main Extinguisher Types

Water (red label)

The workhorse for Class A fires in offices, schools and warehouses full of ordinary combustibles. Simple and effective, but never for electrical equipment, liquids or cooking oils.

Foam (cream label)

Covers Class A and Class B, making it a good general choice where flammable liquids are stored or used. Many modern foam units are tested for accidental discharge near electrical equipment, but they are not an electrical extinguisher.

Carbon dioxide (black label)

The standard choice for electrical risks such as server rooms, switchgear and offices full of equipment. CO2 leaves no residue. The discharge horn gets extremely cold, so users should hold the handle only, and rooms should be ventilated afterwards.

Dry powder (blue label)

Effective on Class A, B and C fires and often seen in vehicles and outdoor settings. Indoors it creates a dense cloud that obscures escape routes and is harmful to breathe, so it is generally unsuitable for enclosed spaces.

Wet chemical (yellow label)

Designed for Class F cooking oil fires in commercial kitchens. It cools the oil and seals the surface. Any premises with deep fat fryers should have one, alongside a fire blanket.

Siting: Where Extinguishers Should Go

• On escape routes and near exits, so users always have an escape at their back
• Next to specific hazards, such as a wet chemical unit near the fryers
• Fixed on brackets or stands at a consistent height, never on the floor behind a pot plant
• Clearly signed, particularly where the extinguisher itself is not visible
• Close enough that nobody travels more than about 30 metres to reach one suitable for a Class A fire

Checks and Maintenance

Good practice, reflected in BS 5306-3, is a monthly visual check by someone in-house: is the extinguisher in place, unobstructed, at the right pressure, with its tamper seal intact and no visible damage? Record what you find. On top of that, a competent engineer should service every extinguisher annually, with extended service or replacement at intervals depending on type.

People, Not Just Equipment

An extinguisher is only useful in the hands of someone who knows when to fight a small fire and, just as importantly, when to leave it and get out. That judgement, plus hands-on familiarity, is exactly what fire awareness training builds.

Integral Safety provides Fire Awareness training and carries out fire risk assessments for businesses across the East Midlands. Contact us if you would like either arranged.