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23/10/2025 • by Megan Downing
A CO2 fire extinguisher is an extinguisher that contains non-flammable carbon dioxide gas. It replaces the oxygen within the fire with carbon dioxide, preventing the fire from burning and smothering the flames. CO2 extinguishers are often a vital safety measure in many buildings, especially where electrical equipment is involved.
A CO2 fire extinguisher is used for 2 fire types. It is the go-to extinguisher for electrical fires, and also works on Class B fires.
Electrical fires are exactly as described, fires started by electrical faults, such as faulty wiring, outdated electrical equipment and overloaded circuits.
Class B fires are fires started by flammable liquids such as petrol, diesel and oils.
A CO2 extinguisher has a red cylinder with a black label that reads ‘CO2’. The nozzle also often has a noticeable black horn. There should also be a CO2 extinguisher ID sign next to the extinguisher.
A CO2 extinguisher is red with a black band or label that reads ‘CO2’. This makes them easy to quickly identify and use to tackle electrical and Class B fires.
A CO2 extinguisher can be used on electrical and Class B fires in unconfined spaces.
Common examples of what CO2 fire extinguishers are used on include the following:
· Electrical equipment fires
· Petrol, diesel and oil fires
· Fires in laboratories with electrical apparatus
· Fires in engine rooms or plant rooms with electrical panels
· Fires in offices and workshops where electrical tools or appliances are present.
CO2 fire extinguishers should never be used in confined or poorly ventilated spaces, or on fires outside of Class B and electrical categories.
In enclosed areas, the release of carbon dioxide can rapidly reduce oxygen levels, posing the risk of asphyxiation. Using the extinguisher on the wrong fire type can also make the situation worse, potentially causing the fire to spread or reignite.
CO2 extinguishers and ABC extinguishers are not the same. As mentioned, a CO2 extinguisher should not be used on Class A or C fires or any other fire type apart from electrical and Class B.
CO2 extinguishers are safe to use indoors, but should not be used in confined spaces. When used, the quick rise in CO2 levels and consequent displacement of oxygen can lead to the risk of asphyxiation.
CO2 fire extinguishers are typically placed near exits, fire alarm call points and high-risk areas such as server rooms, offices, and workshops. Having the extinguishers located near the exit allows the user to stay near a safe escape route whilst combating the flames.
A CO2 fire extinguisher works by releasing non-flammable carbon dioxide gas that replaces the oxygen. As is known through the fire triangle principle, a fire without oxygen can no longer be sustained because one of the three key elements is removed. These 3 key elements are heat, fuel, and oxygen.
Due to a CO2 extinguisher not having a pressure gauge, the only way to tell if a CO2 extinguisher is full is to weigh it and compare it to the weight at manufacture. This is a common process carried out for extinguisher servicing to establish whether the CO2 extinguisher is still full.
If the CO2 extinguisher is not damaged, it can be refilled with CO2 gas. CO2 extinguishers should only be refilled by certified technicians.
CO2 extinguishers are recommended for use with electrical fires. Due to carbon dioxide being a non-conductive gas, it safely smothers the flames without increasing the risk of electric shock or short circuits.
CO2 extinguishers are ideal since they minimise the damage to electrical equipment. They are safe to use on electrical equipment and leave behind no residue, reducing the damage caused after a fire.
CO2 extinguishers are manufactured to last 10 years from the manufacturer’s date. After this date, and provided there have been no signs of damage or wear beforehand, extinguishers should be refurbished or replaced.
CO2 extinguishers expire and should be refurbished or replaced typically 10 years from the manufacturer's date. Fire Protection Shop supplies a wide range of CO2 fire extinguishers in the UK to ensure you’re protected and compliant.
At Fire Protection Shop, we supply our own FireShield CO2 fire extinguishers, trusted by businesses across the UK for their outstanding performance and reliability.
