A Guide To The Different Types Of Fire Extinguishers In The UK
Learn about the different types of fire extinguishers developed to effectively deal with various fire classes.
Fire extinguishers are an important part of any building’s fire safety strategy. In the UK, fire extinguishers are manufactured to meet the BS EN3 standard, with the different types of fire extinguishers having their own colour code for easy identification. As there are different types of combustible materials and fuels that may ignite a fire, there is a need for the corresponding type of fire extinguisher to be installed in the building.
Types of Fire
Class A Fires
These are the most commonly encountered fires in homes and workplaces. Examples are fires that involve coal, paper, straw, textiles, wood, and other flammable solid materials.
Class B Fires
These fires are caused by flammable liquids except for cooking oil. Examples of flammable liquids under this fire class are diesel, petrol, paint, and spirits
Class C Fires
These are fires caused by flammable gases. Examples are butane, hydrogen, methane, natural gas, and propane.
Class D Fires
These fires are caused by flammable metals such as aluminium, lithium, and magnesium, and mostly occur in industrial settings
Electrical Fires
These fires involve electrical appliances or equipment and occur at home, in the office, and anywhere electrical equipment or appliances are used. Once the electrical item that caused the fire has been switched off or removed, the fire changes class based on the surrounding material set alight by the electric current. Electrical fires do not have their own full class as the surrounding materials can fall under the other fire classes.
Class F Fires
These are fires that typically happen in kitchens and other food preparation spaces and involve cooking oil and lard heated to high temperatures, and also butter and grease build-up.
There are five main types of fire extinguishers, with different sub-types for the Powder and Water Fire Extinguishers, bringing the total to eight types of extinguishers. Each type is formulated to extinguish corresponding fire classes.
Types of extinguishers in detail
Carbon Dioxide fire extinguishers
Colour Code:
Black
Best For:
Class B Fires and Electrical Fires
Carbon Dioxide (CO2) fire extinguishers are best used on fires caused by flammable liquid and those that involve electrical equipment. CO2 extinguishers are also considered one of the cleanest types as they do not leave a residue.
How it works:
CO2 extinguishers work by suffocating fires when they displace the oxygen in the air that fires need to burn.
Location:
CO2 extinguishers are mainly used in computer server rooms. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
Carbon dioxide dissipates rapidly which may re-ignite fires when oxygen becomes present in the air again. CO2 fumes are poisonous and even a small increase in CO2 levels can be deadly. Thus, a confined small space such as a server room must be ventilated as soon as the fire is under control. This type is not for use in kitchen pan fires as it can blow the burning fat out of the pan and into the stove flames.
Powder Extinguisher (Standard/Multi-Purpose)
Colour Code:
Blue
Best For:
Class A Fires, Class B Fires, Class C Fires, Electrical Fires
Also referred to as ABC extinguishers, standard dry powder extinguishers have the versatility to extinguish Class A, B, and C Fires, as well as those that involve electrical equipment. This type is most recommended for fires caused by flammable gases.
How it works:
The extinguishing agents in the powder of this type of extinguisher cool down the flames which therefore inhibits the fire.
Location:
Garage forecourts, large boiler rooms, and premises where flame cutting, and welding are done are some examples of premises where this type of extinguisher is recommended. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
While safe to use on live electrical equipment, the powders may not penetrate deeply in crevices where there might still be smoldering material. The same goes for fires in bedding or upholstery where there may still be embers that can re-ignite the fire. The powders can also be inhaled and may impair vision; thus, they are better used in forecourts or well-ventilated workshops rather than in enclosed spaces.
Dry Powder Extinguisher (Special Powders)
Colour Code:
Blue
Best For:
Class D Fires
This type of dry powder extinguisher is used only for inflamed metals such as lithium, magnesium, and sodium.
How it works:
The powders in a specialist dry powder extinguisher extinguish a fire by forming a crust which insulates the flaming metal. This action prevents it from spreading to nearby combustible materials as well as preventing oxygen in the air from reacting with the metal on fire.
Location:
Must be readily available in workplaces where flammable metals are in use. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
Take extra precautions when in enclosed spaces due to inhalation risk.
Foam Extinguisher (AFFF)
Colour Code:
Cream
Best For:
Class A Fires, Class B Fires
Foam fire extinguishers are best for fires caused by flammable liquid such as petrol and paint. They are also effective on fires that involve combustible solids like paper, textiles, and wood.
How it works:
The foaming agents on foam extinguishers work by creating a cooling effect on the fuel. Additionally, the foam floats on top of the burning material creating a barrier between it and the flames, which then extinguishes the fire. This layer of foam also prevents the fire from reigniting.
Location:
Foam extinguishers are commonly found in most buildings, both residential and commercial, as flammable liquids and combustible solids are likely to be found here. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
As this type of fire extinguisher is water-based, it is not for use on kitchen fires (chip pan fires), those that involve electrical equipment, and flammable metals.
Water Extinguisher
Colour Code:
Signal Red
Best For:
Class A Fires
This type of extinguisher is best for controlling fires caused by organic materials such as cloth, coal, fabrics, paper, plastics, and wood.
How it works:
Water extinguishes fire due to its cooling effect on the burning material, which causes it to burn at an exponentially slower rate until the flames are extinguished.
Location:
Most buildings contain organic materials that carry a fire risk and therefore this type of extinguisher is needed. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
Water extinguishers should not be used on burning fats or oils, flammable gases and liquids, and inflamed electrical equipment.
Water Mist Extinguisher (De-Ionised Water)
Colour Code:
Signal Red on a white background
Best For:
Class A Fires, Class B Fires, Class C Fires
The water mist extinguisher has a broad-spectrum application as it can safely extinguish Class A, B, and C fires. Models that are filled with de-ionised water and have been dielectrically tested to 35k volts may be used on electrical fires if applied from a safe distance of 1m. The de-ionised water mist does not conduct electricity, nor does it form puddles that could conduct electricity.
How it works:
A water mist extinguisher is equipped with a type of nozzle which turns water into microscopic particles. This water mist suffocates the fire until it is extinguished. The mist also creates a barrier between the person using the extinguisher and the fire.
Location:
Due to its broad-spectrum coverage of different fire classes, water mist extinguishers are ideal for residential properties, offices, schools, hospitals, and other workplaces. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
Water mist extinguishers cannot be used on burning metals and chip pan fires. The user must be sure that the water mist extinguisher has been certified to have de-ionised water and been dielectrically tested before using it on an electrical fire. Some appliances or electrical equipment can still maintain an electric charge that may be lethal even after being switched off.
Water Spray Extinguisher (Water with additive)
Colour Code:
Signal Red
Best For:
Class A Fires
This type of extinguisher differs from the traditional water extinguisher also used on Class A fires in that it is equipped with a spray nozzle and contains additives.
How it works:
With the spray nozzle, this extinguisher can cover a greater surface area quicker than the jet nozzle of a typical water extinguisher. Aside from extinguishing fire more rapidly, the additives make the water particles penetrate deeper into the burning material thus decreasing the chances of the fire restarting.
Location:
Residential and commercial buildings with combustible organic materials must have this extinguisher accessible to occupants. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
This water-based extinguisher is not for use on burning metals, fats and oils, or electrical equipment.
Wet Chemical Extinguisher
Colour Code:
Canary Yellow
Best For:
Class F Fires, Class A Fires
Wet chemical extinguishers are best for kitchen fires or those that involve cooking oils, kitchen grease, and fat. This type can also be used on Class A fires but only when foam or water extinguishers are not on hand.
How it works:
This type of extinguisher contains a solution containing potassium salts. The wet chemical is sprayed as a mist which not only cools the flames but also prevents the oils from splashing out. Meanwhile, the potassium salts produce a saponification reaction which has a blanketing effect on the burning fat or oil that eventually extinguishes the flames.
Location:
Wet chemical extinguishers are found mostly in commercial kitchens. Place the extinguishers near the source of fire risk or near the fire exits.
Caution:
Since the saponification occurs only with vegetable oils and animal fats, this type of extinguisher cannot be used on other flammable liquids such as those covered under Class B fires.
When purchasing fire extinguishers, make sure that
- they meet the required British Standard,
- they have the correct certification, and
- the certification is carried out after delivery, on-site.
Extinguishers could get damaged in transit, so any certification done by suppliers before delivery would be useless. For more information about fire extinguishers, including the bigger picture scenario of your building’s fire safety strategy, don’t hesitate to contact us.
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