CO2 Fire Extinguisher Use Guide

Carbon dioxide or Co2 fire extinguishers are the best option for extinguishing electrical fires. Although some other extinguisher types can be used (such as foam fire extinguishers), none other can as effectively cool and remove the oxygen supply from an electrical fire. Carbon dioxide is a solid barrier between the fire source and oxygen, which extinguishes it.

co2 fire extinguisher

CO2 fire extinguishers can also be used on Class B fires involving flammable liquids. However, there are several fire classes in which a C02 fire extinguisher should not be used.

For example, if you were to use a C02 fire extinguisher on an oil fire, it could make the fire worse.


Find the Right CO2 Fire Extinguisher

How Do CO2 Fire Extinguishers Work?

Inside a CO2 fire extinguisher, you’ll find carbon dioxide in liquid form and held under immense pressure.

When you pull the lever on a carbon dioxide fire extinguisher, the pressure is reduced by the attached horn, and the carbon dioxide expands back into a gas. This rapid change in the chemical’s property makes the discharge icy cold.

The carbon dioxide gas that leaves the canister is effectively dry ice, which helps to cool the flames somewhat (although not as effectively as foam and water fire extinguishers). This partially tackles the ‘heat’ side of the fire triangle.

The carbon dioxide is sprayed over the fire at a high speed, rapidly displacing the oxygen feeding the fire. Carbon dioxide is heavier than oxygen, so once it comes into contact with fire, it effectively creates a barrier between the flames and the air. This cuts off the crucial ‘oxygen’ part of the fire triangle and extinguishes the flames.


What Is A CO2 Fire Extinguisher Used For?

CO2 fire extinguishers are primarily used to extinguish electrical fires.

Electrical fires can start due to overheating, electrical wire failure, appliance breakdown, faulty electrical plug sockets, and a whole host of other reasons. For this reason, CO2 is one of the most commonly needed fire extinguishers for office space.

When using a CO2 fire extinguisher, you should only target the combustible electric equipment. This extinguisher type cannot extinguish fires related to combustible solids. So if the fire has spread onto wood, paper, or any other solid materials, you’ll need to use another extinguisher type, such as a dry powder extinguisher (or any other Class A extinguisher).

Like several other fire extinguishers, you should not use a CO2 fire extinguisher in a confined space. Given that the tool’s main function is to displace oxygen, it can be hugely detrimental to those within proximity and can even lead to asphyxiation.

CO2 fire extinguishers are also particularly ineffective when it comes to outdoor use, as the CO2 can easily be blown away by the wind.


Where can a C02 fire extinguisher be used?

CO2 fire extinguishers tend to come in either 2kg and 5kg sizes and can commonly be found anywhere that works with electrical equipment, including the following:

  • Computer server rooms
  • Data centres
  • Offices
  • Schools
  • Shops
  • Hospitals

What Type Of Fire Is A CO2 Extinguisher Used For?

Carbon dioxide extinguishers are made primarily for electrical fires but may also be used on Class B fires.

Electrical fires

Carbon dioxide fire extinguishers work best at extinguishing electrical fires involving the likes of faulty electric panels or wiring.

It is safe to use carbon dioxide extinguishers on burning electrical equipment that is still live. Although, it is still recommended to disconnect the power supply to prevent reignition.

Some foam fire extinguishers can be used on electrical fires, but only if it’s possible to safely disconnect the power supply.

Carbon dioxide is safe to use on an electrical fire as it is dry and does not conduct electricity (unlike wet and foam fire extinguishers). It also does not leave any residue afterwards (gas is completely harmless to electric devices), which protects the electrical equipment for future use.

However, the cold temperature of the CO2 could negatively impact sensitive electrical equipment. So, a carbon dioxide extinguisher may damage your electrical equipment in certain instances.


Class B fires

It is possible to use a carbon dioxide extinguisher on a Class B fire. This means fires involving flammable liquid such as paint, diesel, or petrol.

Carbon dioxide does not come out in a liquid form, so it does not risk spreading a liquid fire further.

However, you should not use a carbon dioxide fire extinguisher on a cooking oil fire (Class F). Although cooking oil and grease may still technically be liquids, using a carbon dioxide extinguisher could cause the burning liquid to splash and burn those within proximity. It may also cause the liquid fire to spread or increase in intensity.


What Not To Use CO2 Extinguishers For

Besides Class F fires, CO2 fire extinguishers should also not be used for:

Class A fires

Although carbon dioxide is particularly harmful to solid materials and won’t spread the fire further, carbon dioxide fire extinguishers are not effective at extinguishing Class A fires. The main type of extinguisher used on paper, wood, and other solid combustibles is a water fire extinguisher.


Class C fires

Similarly, CO2 fire extinguishers are not recommended for putting out Class C fires, which are fires that involve combustible gases.


What Colour Is A CO2 Fire Extinguisher?

CO2 fire extinguishers come in a standard red extinguisher canister, which features a black label that reads ‘CO2’.

The extinguisher should also feature an ID nearby this label that will read ‘CO2 extinguisher’. If you’re in a hurry, you can easily identify a CO2 extinguisher by the black horn found at the end of the nozzle.

See Also: Fire Extinguishers Colours guide – how to identify extinguishers via the label colour coding system.


How To Use A CO2 Extinguisher

Carbon dioxide fire extinguishers are easy to use but, at the same time, extremely dangerous if mishandled.

To safely use a CO2 extinguisher, follow these instructions:

Step 1 – Take off the safety pin

Like with most extinguisher types, removing the safety pin will break the tamper seal and allow you to use the CO2 extinguisher freely.

Step 2 – Hold the extinguisher correctly

Never touch the horn, as this part of the extinguisher will reach extremely cold temperatures as you discharge the CO2, which could cause cold burns. Ignore this if your extinguisher has a frost-free horn.

Step 3 – Discharge the CO2

Standing at a safe distance, pull the lever and extinguish the fire. Aim the nozzle directly at the fire if you’re tackling an electrical equipment fire. If you’re extinguishing a flammable liquid fire, aim first at the base of the fire and carefully draw the nozzle across the rest of the fire.


Final Thoughts

If your business uses expensive electronic equipment, your fire safety provisions should definitely include a C02 fire extinguisher.

Even if your equipment is not expensive, having electronics poses fire risks. The best way to extinguish an electric fire is with carbon dioxide.

Further Reading

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