When Would It Be Dangerous to Use A Carbon Dioxide Fire Extinguisher?

Carbon dioxide fire extinguishers, also known as CO2 extinguishers, can be extremely effective when used in the right circumstances. They’re commonly used for electrical fires and Class B flammable liquid fires, making them a popular option for offices, server rooms, workshops, garages, manufacturing environments, and commercial premises with electrical equipment.

However, a CO2 fire extinguisher isn’t suitable for every fire risk. It can be dangerous to use a carbon dioxide extinguisher when dealing with flammable gases, cooking oils and fats, deep seated fires involving solid materials, or fires in confined spaces where ventilation is limited.

In this blog, we’ll explore when it would be dangerous to use a carbon dioxide fire extinguisher in more detail, along with looking at how a CO2 extinguisher works and the main uses that businesses should be aware of.

What is a CO2 fire extinguisher?

A CO2 fire extinguisher is a portable fire extinguisher that uses carbon dioxide gas to tackle certain types of fire. Carbon dioxide, also known as CO2, is a colourless gas with no smell. It’s found in many everyday places, from fizzy drinks to natural atmospheric gases, but it’s also useful in fire safety because of the way it affects the fire triangle.

A fire needs heat, fuel, and oxygen to continue burning. Carbon dioxide fire extinguishers work by reducing the oxygen around the fire, helping to smother the flames. Because CO2 doesn’t leave the same residue as foam, powder, or wet chemical extinguishers, it’s often used in areas where electrical equipment or sensitive items are present.

This makes CO2 extinguishers a common choice for commercial environments where electrical fire risks need to be managed carefully.

How do carbon dioxide fire extinguishers work?

Carbon dioxide fire extinguishers work by releasing CO2 gas at high pressure. When the extinguisher is discharged, the carbon dioxide comes out through the hose and horn, surrounding the fire and reducing the oxygen available to it. Without enough oxygen, the fire is smothered and the flames can be extinguished.

CO2 is also very cold when discharged, which can have a cooling effect on the fire. However, this low temperature is also one of the reasons carbon dioxide extinguishers must be handled correctly, as there is a risk of frost burn if the user holds the wrong part of the extinguisher or if the horn isn’t designed to protect against the extreme cold.

Carbon dioxide is particularly useful where water-based extinguishers would be unsafe, such as around electrical equipment. However, it’s important to understand that CO2 extinguishers don’t remove the fuel source, so there can still be a risk of reignition if the fire isn’t fully extinguished or the power supply hasn’t been isolated.

What are the main CO2 extinguisher uses?

CO2 extinguishers are mainly used for two types of fire risk: electrical fires and Class B fires involving flammable liquids. This makes them useful in many commercial and industrial environments where these types of fire risks are present.

Some common CO2 extinguisher uses include:

• Electrical equipment fires
• Server rooms and IT areas
• Offices with computers, printers, and electrical equipment
• Workshops and manufacturing settings
• Garages and automotive environments
• Areas with certain flammable liquid risks
• Electrical cupboards, plant rooms, and control rooms, where suitable

Class B fires involve flammable liquids such as petrol, paint, solvents, or oil, but not cooking oils or fats. CO2 extinguishers are also widely used for electrical fire risks because they can put out the flames without leaving residue behind. This is important in areas containing computers, servers, switchgear, or other electrical equipment, where using the wrong extinguisher type could create additional damage or danger.

When it comes to using the right extinguisher, staff training is important. Employees should understand which extinguisher types are suitable for different fire risks, how to operate a portable fire extinguisher safely, and when it’s safer to evacuate rather than attempt to tackle a fire.

When is it dangerous to use a carbon dioxide extinguisher?

Although carbon dioxide fire extinguishers are highly useful in the right setting, they can be dangerous if used incorrectly or in the wrong environment. The main risks of CO2 extinguishers include asphyxiation, high pressure discharge, rapid discharge, frost burn, and the potential for reignition.

With that in mind, here are some situations where it would be dangerous using a carbon dioxide extinguisher:

Confined or poorly ventilated spaces

If a carbon dioxide extinguisher is used in an enclosed or poorly ventilated area, there is a serious risk of asphyxiation. CO2 works by displacing oxygen around the fire, but in a confined space it can also reduce the oxygen available for people nearby.

This is why CO2 extinguishers should be used with care in small rooms, cupboards, enclosed plant areas, or any space where ventilation is limited. If it’s not safe to use the extinguisher, evacuation should always take priority.

Without adequate training

CO2 extinguishers discharge at high pressure and empty quickly, which means the person using one needs to understand how to handle it correctly and act fast. When discharged, carbon dioxide changes from liquid into gas and creates a strong force through the hose and horn, so incorrect handling can lead to injury, including wrist strain. 

The gas is also extremely cold as it leaves the extinguisher, which can create a frost burn risk if the horn is held incorrectly or the unit isn’t fitted with a suitable frost free horn. Anyone expected to use a CO2 extinguisher should be properly trained on how to hold it, how to aim it, how quickly it will discharge, and when to stop and evacuate instead.

Electrical risks with potential reignition

CO2 extinguishers are suitable for many electrical fire risks, but care is still needed. If a fire started because of damaged wiring, overloaded equipment, or an electrical fault, the power supply should be isolated as soon as it’s safe to do so.

There is a risk of electrocution if someone investigates the source of the fire while the electrical supply is still live. There is also a risk that the fire could reignite if the underlying electrical fault remains active. Wherever possible, the electricity supply should be switched off before or immediately after using the extinguisher.

Unsuitable fire types

While CO2 extinguishers are suitable for Class B and electrical fires, they’re not suitable for a range of fire types. For example, they’re not suitable for cooking oil or fat fires, where a wet chemical extinguisher is usually required. They’re also not suitable for flammable gas fires, as extinguishing the flame without controlling the gas supply can create a serious explosion risk.

CO2 is also not the best option for deep seated Class A fires involving materials such as paper, wood, textiles, or furniture, because it may not cool the material enough to prevent reignition.

Speak to us for your carbon dioxide fire extinguishers

At City Fire Protection, we have years of industry experience in supplying and installing carbon dioxide fire extinguishers for commercial and industrial premises. We can help you choose the right extinguisher type for the specific risks your business faces, ensuring you’re better prepared in the event of a fire.

We can also support with the correct extinguisher placement, servicing and maintenance, replacement, and staff training, ensuring your extinguishers are suitable, accessible, and ready to use when needed. All of our fire extinguishers are manufactured here in the UK, so you can be confident you’re getting high-quality products.

Whether you need advice on the right units for your business, maintenance, or replacement of your current extinguishers, don’t hesitate to contact our team today to discuss your requirements in more detail.