Fire Extinguisher Types and Fire Classes

Fire Class Icon	Fire Class	Type of Fire / Fuel
	Class A Fires	Solid Combustibles Wood, textiles, straw, paper, coal etc.
	Class B Fires	Flammable Liquids Petrol, oils, paints, tar, ether, alcohol, stearin and paraffin.
	Class C Fires	Flammable Gases Methane, propane, hydrogen, acetylene, natural gas and city gas.
	Class D Fires	Flammable Metals Magnesium, aluminium, lithium, sodium, potassium and their alloys.
	Class F Fires	Combustible Cooking Media Cooking oil and grease
	Electrical Fires	Electrical Appliances Computers, electrical heaters, stereos, fuse boxes etc.

 

Fire extinguisher types and their uses

Each type of fire extinguisher is suitable for different fire classes and it is essential that you purchase suitable extinguishers to cover the risks that exist at your premises. Always refer to your fire risk assessment and results of your fire extinguisher survey when purchasing extinguishers.

*We do not recommend using water mist on anything above a 5F rated fire (this is equivalent to an average domestic deep fat fryer).

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Water fire extinguishers

Water fire extinguishers have a red label and a class A rating. They are suitable for fighting fires involving solid combustibles such as wood, paper and fabric. A few models are also safe on electrical equipment if di-electrically tested. Otherwise, care must be taken near electrical equipment.

Water extinguisher uses:

• Offices
• Schools
• Shops
• Hospitals
• Public buildings

Water is often paired with CO2 fire extinguishers to cover all common fire risks. Often the least expensive extinguisher, these extinguishers are not toxic or harmful to the environment as they contain only water. Water extinguishers should never be used to extinguish class F, D or B fires and in some cases could exacerbate the situation if discharged on one of these types of fire.

Water fire extinguishers work by soaking the fire and materials in water, removing the heat and cooling the fire significantly so it can no longer burn.

Fire Classification

 

Water mist fire extinguishers

Water mist fire extinguishers have a white label and are highly effective on class A, B, C and live electrical equipment. These versatile extinguishers contain only de-ionised water but are more effective on a broad range of fire types when compared to standard water extinguishers due to the way the media is dispensed. 

Water mist extinguishers have a superfine spray nozzle that dispenses microscopic droplets of de-ionised water. The mist curtain reduces the supply of oxygen to the fire and cools the materials, preventing reignition. Containing only de-ionised water, water mist is an environmentally friendly media and leaves no messy residue to clean up after discharge.

Any water mist extinguishers displaying the live electrical equipment symbol on the front have been di-electrically tested in accordance with BS EN3 and are suitable for use on live electrical equipment up to 100 volts at a distance of 1m. Some water mist extinguishers are also certified for class F fires, however we do not recommend using water mist on anything above a 5F rated fire (equivalent to a domestic deep fat fryer).

Water mist extinguisher uses

Due to their versatility, water mist extinguishers are ideally suited to any environment that contains mixed fire risks. 

• Offices 
• Schools 
• Shops
• Hospitals
• Public buildings

Many of these settings would usually require a water and CO2 extinguisher to cover class A fires and fires involving electrical equipment. Water mist can cover both of those fire risks effectively, negating the need for two extinguishers.

Fire Classification

 

CO2 fire extinguishers

CO2 fire extinguishers are identified by their black label and usually have a frost-free horn that protects the user from freeze-burns when discharged. They are predominately used on fires involving live electrical equipment, as CO2 is not a conductor. In addition, CO2 extinguishers don’t leave behind any harmful residue so can often be discharged on expensive electrical equipment without causing damage. They were originally designed for use on flammable liquid fires and therefore many also have a class B fire rating.

CO2 extinguisher uses

• Server rooms
• Any room containing a large amount of large electrical equipment 

CO2 extinguishers are also commonly found in offices, warehouses, schools or retail premises paired with water of foam extinguishers. They have traditionally been specified to cover electrical fire risks in these locations but as there are now extinguishers that are both di-electrically tested and cover class A risks, this pairing is not usually necessary.

CO2 extinguishers contain only carbon dioxide gas and care should be taken when discharging them as there is a risk of asphyxiation if used in confined spaces. Frostbite can also occur if the discharged CO2 comes into contact with the users skin (the frost-free horn is designed to prevent this). CO2 extinguishers can also pose a risk of re-ignition as they are not effective as a coolant, and if discharged on class A or class F fires, could actually make the fire worse.

Fire Classification

 

Dry powder fire extinguisher

Dry powder extinguishers have a blue label. They are versatile and can be used on class A (solid combustibles), class B (flammable liquids), class C (flammable gases) and fires involving electrical equipment.

Powder extinguishers (also referred to as dry powder or ABC powder) contain mono-ammonium phosphate which is mixed with other powders. They work by smothering the fire which creates a barrier between the fuel and the oxygen. 

Powder extinguisher uses

• Construction sites
• Garage forecourts
• Vehicles & machinery

Powder extinguishers are ideally suited to outdoor locations as there is a risk of inhalation when discharging them indoors. They are also difficult to clean up when discharged and can cause damage to soft furnishings. 

Fire Classification

 

Wet chemical extinguishers

Wet chemical fire extinguishers (also known as class F extinguishers) have a yellow label and are designed specifically for use on fires involving combustible cooking media such as burning oil and fat. They have an additional class A rating that means they are suitable for use on solid combustibles. Some are also designed for use on class B fires (petrol, diesel, paint, paraffin etc) and fires involving live electrical equipment as indicated on the front of the extinguisher body.

Wet chemical extinguisher uses

• Commercial kitchens
• Deep fat fryers

Containing potassium salts, these extinguishers work by creating a soapy barrier between the fire and the oxygen. This cools the fire and prevents reignition. This type of extinguisher has a special lance applicator nozzle that allows the user to gently dispense the media from a suitable distance. Normal water-based extinguishers with large droplets would cause an 'explosion' of steam and carry burning oils and fats from the container. Equally, a CO2 extinguisher's jet would carry burning oil out of the container and also would have insufficient cooling effect to stop re-ignition.

Fire Classification

 

Foam fire extinguishers

Foam fire extinguishers are identified by their cream label and are designed for class A and B fires plus in some cases fires involving electrical equipment. There are a number of different types of foam fire extinguishers and some are now classified as hazardous to human health and the environment. Foam extinguishers are water-based and contain chemicals that form a ‘frothy agent’. The foam cools and smothers the fire, extinguishing it and preventing reignition.

Foam extinguisher uses

• Offices 
• Schools 
• Shops
• Hospitals
• Public buildings

AFFF foam

This type of foam extinguisher contains toxic fluorine compounds (PFAS) which is harmful to humans and the environment. AFFF foam extinguishers are due to be phased out by law from 2025 and Safelincs have taken the decision to discontinue the sale of this type of extinguisher.

AFFF foam extinguishers are commonly found in many premises across the UK including offices, schools, warehouses, shops and public buildings. The disposal of this type of media is tightly controlled due to its harmful nature.

Fluorine-free foam

Recently, manufacturers have begun to replace AFFF foam extinguishers with fluorine-free foam extinguishers. This type of fire-fighting foam is versatile in application but is a more environmental choice, being free from the harmful PFAS chemicals contained in AFFF foam. Fluorine-free foams can be used on class A and B fires as well as being di-electrically tested for use on electrical equipment.

Fire Classification

 

Service-Free Fire Extinguishers

P50 extinguishers are a relatively new type of fire extinguisher and provide an alternative to steel extinguishers that are more durable and easier to maintain. With a plastic outer casing and super-strong inner core, this type of extinguisher will not corrode and does not require annual servicing from an external technician. With twice the lifespan of a traditional steel extinguisher, P50 service-free extinguishers are 100% recyclable and offer an environmental option. They have a low-carbon manufacture process and offer significant cost savings over their long lifespan.

P50 extinguishers are available in a range of media including water mist and eco-foam. They have a 10-year warranty and excellent fire-fighting capability. Find out more about this type of extinguisher on our P50 information guides. 

 

Still not sure which type you need?

Read our extinguishers by location and extinguishers for vehicles guides for help choosing the correct extinguishers for your requirements.

Or, contact our friendly team on 0800 612 6537 or email support@safelincs.co.uk for help choosing a suitable extinguisher for your location.