Classes of Fire – What are the 6 Different Types of Fires?

Every type of fire burns differently depending on it’s fuel source. Understanding the classes of fire is essential to fighting a fire safely if one breaks out.

Using the wrong fire extinguisher can have catastrophic consequences, and pose a danger to life. For this reason, it is essential to understand the 6 different types of fire. Every workplace must complete a fire risk assessment.

These vital safety documents look at which fire classes the work environment is at risk from. The classification system then gives easy insight into what fire safety equipment and methods should be used on the premises.

What Classes are Fire Divided Into?

Fires are grouped into 6 separate classes to identify which extinguisher to use. Each fire class comes with its unique hazards and should be tackled in a particular way.

The 6 classes of fire are as follows:

• Class A Fires: Solids Combustibles such as paper and cardboard.
• Class B Fires: Flammable Liquids including cleaning products and paints.
• Class C Fires: Flammable Gases like methane or propane.
• Class D Fires: Flammable Metals with examples such as sodium and potassium.
• Class F Fires: Cooking Oils and Fats are most often found in kitchen environments.
• Electrical Fires: Fires involving electricity can be very hazardous and can encompass any of the above fire classes, depending on what burns around it.

Class A Fires – Solid Combustibles

Class A fires involve solid combustibles such as paper.

This type of fire is typically found in work environments such as offices. With materials such as cardboard, furniture, wood and fixtures in abundance, it is easy to see why these fires are common. Most work environments have these sources of ignition.

Fires involving these types of combustible materials can easily ignite and are difficult to extinguish.

Class A Fire Extinguishers

Water fire extinguishers should be used on Class A fires.

These are commonly used in the workplace due to their ability to tackle many fire types. This type of extinguisher has a red label and they work by cooling the fire with its spray.

You should not use a CO² fire extinguisher on Class A fires.

Class B Fires – Flammable Liquids

Class B fires involve flammable liquids such as petrol.

Many workplace environments have flammable liquids on site. Examples include petrol, paints, adhesives, cleaning supplies, inks and solvents. These sources of ignition can light very quickly and spread at an astronomical pace.

Class B Fire Extinguishers

Either foam or dry powder extinguishers should be used on a Class B fire.

Both of these extinguishers will safely put out a fire that is being fuelled by a flammable liquid.

Foam extinguishers have a cream label and the foam acts as a barrier between the flames and the fuel. Powder extinguishers are identified by their blue label. Again, they fight fire by creating a barrier between the fuel and the oxygen.

Class C Fires – Flammable Gases

Class C fires involve flammable gases such as natural gases.

Working in an environment with gas is dangerous at the best of times and the fire hazards are potentially lethal. For this reason, gases must be kept in suitable storage and handled with care.

Class C Fire Extinguishers

The extinguisher that should be used on a Class C fire is a dry powder extinguisher.

The first course of action though is to ensure the gas has been switched off. Environments such as petrol stations should all have a dry powder extinguisher ready to deal with any fires.

Class D Fires – Flammable Metals

Class D fires involve flammable metals, including titanium and magnesium.

There isn’t enough awareness of metal fires and their hazards, with many assuming they aren’t even combustible. Metals such as sodium are not only combustible but are also heat conductors.

This means they will help a fire to spread and will do so, quickly. This type of fire can be very dangerous as the metal will soften under intense heat. This can impact the structure of the building and its safety.

Class D Fire Extinguishers

The extinguisher that should be used on a Class D fire is a dry powder extinguisher. Work environments such as welding workshops should always have a specialist dry powder extinguisher on site.

Water should never be used on a fire involving burning metals as it will worsen it.

Class F Fires – Cooking Oils & Grease

Class F fires involve cooking oils and fats which are in commercial and domestic kitchens.

This fire class is typically caused by either frying pans or deep fat fryers. Usually, the oil heats up far too quickly which results in flames being produced. This is why it is important to have an adequate number of staff in the kitchen at all times. Any food being cooked on the premises should be supervised at all times.

When a pan heats too quickly, the oil can be agitated and splash onto the worktops. This, of course, increases the likelihood of the fire spreading further.

Class F Fire Extinguisher

A wet chemical extinguisher should be used on a Class F fire. This is the only appropriate fire extinguisher for this fire class.

Wet chemical extinguishers have a yellow label and they provide a layer of foam directly on the hot oil. This prevents the oxygen from getting to the fire and essentially smothers it into submission. Providing the fire is still contained in the pan, it may be appropriate to use a fire blanket.

Electrical Fires – Electrical Appliances

Electrical fires involve appliances such as PCs, photocopiers, and refrigerators.

Electrical fires are different as electricity is more an ignition than a fuel but they are still extremely hazardous. Electrical fires can fall into any of the above classes since once ignited, they can be fuelled by any of the surrounding materials.

CO² fire extinguishers should be used on an electrical fire. Dry powder extinguishers can also be used on this fire class. It is important to turn off the electrical supply first if you can.

They will both successfully suffocate the fire by cooling and shutting off its oxygen supply.

FAQs