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When a fire breaks out, having the right extinguisher on hand can make all the difference. However, not all fire extinguishers work the same way, and using the wrong one can be ineffective or even dangerous. That’s why it’s essential to understand what a carbon dioxide extinguisher is used for and how it fits into overall fire safety.

CO₂ fire extinguishers are specifically designed to combat electrical fires and flammable liquid fires without leaving behind harmful residue. Unlike other extinguisher types, they don’t use water or foam but instead work by displacing oxygen, suffocating flames quickly. Because of this, they are commonly found in areas with expensive electronic equipment, industrial settings, and commercial kitchens.

Let’s explore the best applications for CO₂ fire extinguishers, their advantages, and the key safety precautions you need to know.

Key Takeaways

• CO₂ fire extinguishers effectively suppress Class B and Class C fires by displacing oxygen and cooling the flames.
• They should never be used in confined spaces without ventilation due to the risk of oxygen depletion.
• Regular maintenance and recharging after every use are essential to ensure CO₂ extinguishers remain effective.

Carbon Dioxide (CO₂) Fire Extinguishers

CO₂ fire extinguishers are a go-to solution for tackling electrical fires and flammable liquids, offering fast fire suppression without leaving behind any messy residue.

Composition and mechanism

Unlike water- or foam-based fire extinguishers, carbon dioxide fire extinguishers contain compressed CO₂ gas stored under extremely high pressure. When discharged, the CO₂ rapidly expands, displacing oxygen and cutting off the fire’s oxygen supply, which effectively suffocates the flames.

Additionally, CO₂ creates a cold presence as it is released, cooling the burning material. This rapid expansion can even cause dry ice to form at the discharge point, helping to control the fire but also posing a risk of cold burns if not handled properly.

Physical characteristics

CO₂ extinguishers have some distinct features that set them apart from other extinguisher types:

• No pressure gauge – Unlike many other fire extinguishers, CO₂ models do not have a pressure gauge, as the gas is stored in a liquid state and released as needed.
• Frost-free horn – The discharge horn is specially designed to prevent users from getting cold burns due to the extreme cold of the expelled CO₂.
• Hard horn and wide discharge range – The CO₂ extinguisher has a horizontal discharge range that allows it to cover small fires effectively. However, in outdoor settings, wind drift can reduce its effectiveness.

CO₂ extinguishers are ideal for environments with energized electrical equipment, such as offices, data centers, and workshops, where they can quickly extinguish fires without damaging sensitive devices. However, they must be used with caution in confined spaces, as excessive CO₂ can reduce breathable air levels.

Appropriate Uses of CO₂ Fire Extinguishers

Carbon dioxide fire extinguishers are highly effective in specific fire situations but are not meant for every type of blaze. Their unique properties make them ideal for Class B fires (flammable liquids and gases) and Class C fires (electrical fires), where they can quickly suppress flames without causing further hazards.

Class B fires

Class B fires involve flammable liquids like oil-based paints, gasoline, and solvents, as well as flammable gases such as propane and butane. These liquid fires spread rapidly and can be difficult to control with water-based fire extinguishers, which may cause the burning liquid to splash and spread the flames.

CO₂ fire extinguishers are effective for Class B liquid fires because they:

• Displace oxygen, suffocating the flames before they can spread.
• Leave no residue, preventing contamination of materials.
• Provide a cooling effect, reducing the risk of re-ignition.

However, CO₂ extinguishers have a horizontal discharge range, meaning their effectiveness can be reduced in outdoor areas where wind drift can blow the CO₂ away from the fire.

Class C fires

Fires that involve energized electrical equipment fall under Class C fires, which include burning appliances, circuit breakers, and power tools. Using the wrong fire extinguishers on an electrical fire—such as a water-based ABC extinguisher—can lead to electrical shock and equipment damage.

CO₂ extinguishers are the preferred choice for electrical fires because they:

• Are non-conductive, eliminating the risk of electric shock.
• Do not damage expensive electronic equipment like computers and servers.
• Can be used in confined spaces without leaving behind harmful residue.

However, carbon dioxide fire extinguishers should not be used on cooking oils and fat fires (Class F fires) as they lack the necessary cooling effect to prevent re-ignition.

Limitations and Safety Precautions

While carbon dioxide fire extinguishers are highly effective for certain types of fires, they are not a one-size-fits-all solution. Understanding their limitations and handling precautions is crucial for safe and effective use.

Ineffectiveness on Class A fires

CO₂ extinguishers are not ideal for Class A fires, which involve ordinary combustibles like paper, wood, and fabric. Unlike foam or water-based fire extinguishers, CO₂ fire extinguishers do not provide a lasting cooling effect. If Class A materials are smoldering, another extinguisher type should be used to ensure the fire is completely extinguished.

Hazards in confined spaces

Using a CO₂ extinguisher in an enclosed area poses a serious risk because it displaces oxygen to suffocate the flames. However, this also reduces breathable air for anyone nearby, potentially leading to asphyxiation.

• Never use CO₂ extinguishers in confined spaces unless proper ventilation is available.
• Evacuate immediately after discharge to allow oxygen levels to stabilize.

Handling precautions

Since CO₂ fire extinguishers release gas at extremely low temperatures, improper handling can cause cold burns or frostbite.

• Do not touch the discharge horn during operation, as it becomes dangerously cold.
• Use the safety pin and handle correctly to prevent accidental discharge.
• Maintain a safe distance while using the extinguisher to avoid exposure to freezing gas.

Proper Operation of a CO₂ Fire Extinguisher

Using a CO₂ fire extinguisher correctly is essential for putting out a fire quickly and safely. While these extinguishers are effective against electrical fires and flammable liquids, improper use can reduce their effectiveness or create additional hazards.

How to use a CO₂ extinguisher

The PASS technique is the standard method for using all fire extinguishers, including carbon dioxide fire extinguishers: