CO2 Fire Extinguishers: A Guide

When it comes to commercial fire safety, selecting the correct fire extinguisher is essential for protecting employees, colleagues and premises. Different fire risks require different extinguishers, and using the wrong type can reduce effectiveness or create additional hazards.

A CO2 fire extinguisher (also known as a carbon dioxide fire extinguisher) is specifically designed for environments where electrical equipment and flammable liquids present a fire risk. Commonly used in offices, server rooms, plant rooms, and industrial settings, a CO2 extinguisher provides fast, residue-free fire suppression, making it particularly suitable for electrical fires and situations where protecting sensitive equipment is a priority.
 

What Type Of Fire Can A CO2 Fire Extinguisher Be Used On?

CO2 extinguishers are used almost exclusively to extinguish fires caused by electrical equipment and live cables; however, you can also use them on fires caused by or involving flammable liquid (Class B fires).

There is no other fire extinguisher that can be used to extinguish an electrical fire; the CO2 extinguisher is the only extinguisher that can do this job. A CO2 fire extinguisher can be safely used on electrical fires without increasing the risk of electric shock. It also leaves no residue, making it particularly suitable where sensitive equipment or valuable assets must be protected.

CO2 extinguishers are commonly used for tackling fires involving:

• Computer equipment
• Electrical appliances
• Flammable liquids such as petrol, diesel, paraffin & paint
• Switchgear and fuse boards
• Photocopiers, printers and office machinery
• Laboratory or plant room electrical installations

Because a CO2 extinguisher works by displacing oxygen and cooling the fire source, it is especially effective in enclosed indoor environments where rapid suppression is required. For this reason, CO2 fire extinguishers are widely installed in offices, data centres, commercial premises and industrial facilities.

A CO2 extinguisher should NOT be used for fires involving:

• Wood
• Paper
• Textiles
• Fat (such as deep fat fryers and chip pans)
• Cooking oils

CO2 extinguishers are ineffective on these fire types because they do not sufficiently cool the burning material. While a CO2 extinguisher works by displacing oxygen, fires involving solid combustibles or hot oils can quickly re-ignite once the gas disperses. For these risks, more suitable fire extinguishers include water extinguishers for Class A fires and wet chemical extinguishers for Class F fires, which are specifically designed to cool and suppress burning oils and fats safely.
 

How does a CO2 extinguisher work?

The carbon dioxide within the extinguisher is highly pressurised, so the gas itself is stored as a liquid in the canister. Once you discharge the extinguisher, the liquid CO2 will depressurise into a gas as you spray it onto the fire.

Like other extinguishers, the CO2 extinguisher attacks one of the three elements fire needs to burn - oxygen. Spraying CO2 onto a fire displaces the oxygen around it, discharged carbon dioxide gas spreads over the fire, displacing the oxygen in the surrounding air and effectively suffocating the flames. At the same time, the rapid expansion of the gas produces a cooling effect that helps to reduce the temperature at the fire source.

Unlike other fire extinguishers, no residue or mess is left behind as CO2 extinguishers discharge gas.
 

How To Know If An Extinguisher Is A CO2 Extinguisher

CO2 extinguishers are easy to identify from other extinguishers thanks to a black label with white writing on it that reads ‘Carbon Dioxide Fire Extinguisher’ in line with UK fire extinguisher colour coding standards.

Rather than a hose, most CO2 extinguishers are fitted with a distinctive black discharge horn which helps direct the carbon dioxide gas safely on to the fire.
 

Where Are CO2 Extinguishers Found?

There are specific places that require CO2 extinguishers to be installed to comply with fire safety regulations. These are usually locations that contain electrical equipment, including:

• Offices
• Laboratories
• Casinos
• Server rooms
• Mechanical rooms
• Schools
• Universities

CO2 extinguishers can also be used on Class B fires, they are often found in areas that provide storage for flammable liquids, such as petrol, diesel, and paint.
 

How To Use A CO2 Extinguisher

You can safely use a CO2 extinguisher on relatively small and contained fires. If the fire is in an enclosed space, CO2 extinguishers are not recommended due to the possibility of asphyxiation, as carbon dioxide is poisonous at a concentration of 4%.

Instructions on how to use a CO2 fire extinguisher are displayed on the side of the canister. However, it’s a good idea to familiarise yourself beforehand with them in the event that you ever need to use one.

• Remove the safety pin.
• Aim the CO2 extinguisher's hose at the base of the fire - this is important as you are aiming for the source of the fire.
• Squeeze the lever on the extinguisher.
• Make sweeping movements with the extinguisher's hose while aiming at the fire's base.
• Ensure that you hold the hose at the base and not the nozzle opening. When the freezing CO2 gas is discharged, it could freeze-burn your skin.
• Remember that CO2 extinguishers discharge very quickly so should only be used on small fires that can be rapidly contained.
    

Johnson Controls Fire Extinguisher Solutions

At Johnson Controls, we have a wide range of fire extinguishers to suit your needs:

• Water Mist Fire Extinguishers
  Environmentally friendly and multipurpose to tackle many classes of fire.
   
• Water and Water Additive Fire Extinguishers
  Water based and suitable for Class A fires.
   
• Foam Spray Fire Extinguishers
  Filled with Aqueous Film Forming Foam and suited to Class B flammable liquid fires. You can learn more about foam fire extinguishers with our guide here.
   
• Wet Chemical Fire Extinguishers
  Specially manufacturer for Class F cooking oil and fat fires.
  
  
• Carbon Dioxide Fire Extinguishers
  Suitable for electrical hazards and Class B flammable liquid fires.
   
• Dry Powder Fire Extinguishers
  Designed for mixed fire risk environments including flammable liquids and flammable gasses
    

You can learn more about our range of fire suppression solutions and services here or contact us using the form below.