Carbon Dioxide Fire Extinguisher Class Guide & Safety Tips

How a CO₂ (Carbon Dioxide) Fire Extinguisher Works

The carbon dioxide fire extinguisher, also known as a CO₂ extinguisher, works differently from standard fire extinguishers. Its fire suppression mechanism relies primarily on smothering and cooling effects.

Liquid CO₂ has a high density and instantly vaporizes when released into normal atmospheric pressure. For instance, 1 kg of liquid CO₂ produces around 0.5 cubic meters of gas. This gas displaces the oxygen around the flames, reducing the oxygen concentration below what’s needed to sustain combustion — effectively smothering the fire. Since fires need oxygen to burn, this action helps to extinguish them quickly.

In addition, the vaporization process rapidly absorbs heat from the surrounding air, creating a significant cooling effect that helps control the fire.

Carbon Dioxide

CO₂ Fire Extinguisher: Pros and Cons

Carbon dioxide fire extinguishers are most effective for Class B and Class C fires. While they can be used on small Class A fires, their effectiveness is generally lower than dry chemical or halon fire extinguishers. (Note: Halon extinguishers were phased out starting in 1994 due to their harmful effects on the ozone layer.)

Because of their limitations, CO₂ extinguishers may not be sufficient for larger fires, especially those involving common combustible materials like wood or paper.

Disadvantages of CO₂ Fire Extinguishers

Risk of frostbite:
CO₂ is stored at extremely low temperatures. Touching the nozzle or metal parts during discharge can cause frostbite.
Oxygen displacement hazard:
In enclosed or poorly ventilated areas, using a CO₂ extinguisher can reduce oxygen levels and make breathing difficult. It’s important to evacuate the area quickly after use.
No pressure gauge:
You’ll need to weigh the extinguisher to check if it’s full.
Heavy:
Seamless high-pressure steel cylinders are quite heavy, which makes them harder to handle.
Not rated for Class A fires:
Since it lacks an official Class A fire rating, a CO₂ extinguisher might not meet inspection requirements and may require additional systems or maintenance.

Advantages of CO₂ Fire Extinguishers

No residue:
CO₂ leaves no residue behind and is non-corrosive, which makes it ideal for use around sensitive electronic equipment.
Low environmental impact:
Compared to other agents, carbon dioxide has a lesser impact on the environment.
Safe for valuables:
Commonly used in server rooms or areas with expensive equipment or artwork.

Class B fires involve flammable liquids like gasoline, alcohol, cooking oil, or solvents.
Class C fires involve electrical equipment such as wiring, circuit breakers, transformers, and appliances.

How to Use a Carbon Dioxide Fire Extinguisher

Using a CO₂ extinguisher is relatively simple:

Pick up the extinguisher.
Pull the safety pin.
Stand upwind from the fire.
Aim the horn or nozzle at the base of the flames.
Squeeze the handle firmly.
Sweep from side to side.

⚠️Important Safety Tip: Never hold the discharge horn or metal connection with your bare hand while operating — it can cause frostbite. If using it in a small, enclosed space, evacuate quickly after extinguishing the fire to avoid suffocation.

Recommended: Carbon Dioxide Fire Extinguisher

✔️ Leaves no residue
✔️ Suitable for Class B & C fires
✔️ Seamless high-pressure cylinder
✔️ Extinguishes by smothering and cooling
✔️ 1-year warranty, 5-year shelf life

Carbon Dioxide Fire Extinguisher👉Buy Now

CO₂ vs. Other Fire Extinguisher Types: Environmental and Safety Comparison

Fire Extinguisher Type	Environmental Pollution	Carcinogenic Risk	Respiratory Hazard	Suffocation / Frostbite	Electrical Conductivity	Toxic Substances
Enhanced Liquid	❌ None	❌ None	❌ None	❌ None	❌ None	❌ None
Foam	⚠️ Present	⚠️ Present	❌	❌	⚠️ Yes	⚠️ Possible
Dry Chemical	⚠️ Present	⚠️ Present	⚠️ Yes	❌	❌	⚠️ Yes
CO₂	⚠️ Some	❌ None	⚠️ Yes	⚠️ Yes	❌ None	❌ None
Water	❌ None	❌ None	❌ None	❌ None	❌ None	❌ None

Notes:

⚠️ Present” indicates potential or partial risk depending on the agent used.

CO₂ extinguishers avoid toxic compounds like crystalline silica, PFOS, and PFOA.

CO₂ vs. Other Fire Extinguishing Agents: Effectiveness Comparison

🔥 Fire Extinguisher Effectiveness by Fire Class and Agent Type

Fire Class	Description	ECO-WET Enhanced Liquid	Water	Foam	CO₂	ABC Dry Powder
A	Ordinary Combustibles	⭕ Rapid suppression	⭕ Rapid suppression	⭕ Effective	❌ Not suitable	⭕ Effective
B	Flammable Liquids (e.g., gasoline)	⭕ Effective	🔺 Conditionally effective	⭕ Rapid suppression	⭕ Effective	⭕ Rapid suppression
B	Cooking Oil / Grease	⭕ Rapid suppression	🔺 Conditionally effective	⭕ Effective	❌ Not suitable	⭕ Effective
C	Electrical Fires	⭕ Effective	❌ Not suitable	🔺 Conditionally effective	⭕ Effective	⭕ Effective

Legend

⭕ Rapid suppression
⭕ Effective suppression
🔺 Conditionally effective (requires certified testing)
❌ Not suitable for suppression

Note: Water mist extinguishers can also be used on Class B fires if sprayed in mist form.

文章作者

About Cheng Deh Fire Protection Team

Cheng Deh Fire Protection has over 64 years of experience in fire safety management and certified fire equipment services. Our editorial team works closely with fire safety professionals to ensure that every article is factual, up-to-date, and aligned with local regulations. We are committed to providing trustworthy guidance to enhance public awareness and workplace safety standards.