Carbon Dioxide (CO₂) Fire Extinguisher Cylinders

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Carbon dioxide (CO₂) fire extinguishers are portable fire-fighting devices that suppress fires by interrupting the combustion reaction through oxygen displacement and are particularly effective against Class B and Class C fires.

Fire Classes and Applications

CO₂ extinguishers are especially prominent in liquid and gas-based fires:

• Class B Fires: Flammable liquids such as alcohol, gasoline and oil.
• Class C Fires: Gas fires and electrical fires.

CO₂ extinguishers are preferred for protecting sensitive electrical systems such as computer rooms, transformer stations, laboratories and generator rooms due to their non-conductive properties.

Refilling Process

The refilling of CO₂ fire extinguisher cylinders differs from other types of extinguishers in that it involves the controlled transfer of liquefied gas under high pressure. The refilling process follows these steps:

Emptying and Cleaning

Used or expired CO₂ cylinders are first completely emptied. The cylinder body is inspected internally and cleaned if necessary. This step is particularly important for detecting internal corrosion.

Weight Determination

Since CO₂ cylinders have a fixed volume, the refill quantity is typically calculated by mass. The net fill weight and tare weight marked on the cylinder are used to determine the precise amount of CO₂ gas to be added.

Gas Refilling

The refilling operation is performed using specialized manifold systems by pressurizing the cylinder with liquefied CO₂ gas at approximately -18°C. A scale is used during refilling to ensure the exact specified weight is not exceeded; otherwise, the safety valve may activate or a rupture risk may occur.

Leak Testing and Labeling

After refilling, each cylinder undergoes a leak test. The safety valve, handle, hose and cylinder connections are inspected. A label is affixed to the cylinder indicating the refill date, the name of the company that performed the refill and the next refill due date.

Fire Extinguishing Procedure

For CO₂ fire extinguishers to be effective in fire suppression, they must be used with the correct technique. CO₂ gas suppresses fire by displacing oxygen in the fire zone and simultaneously providing rapid cooling. The following precautions must be observed during use:

Activation and Aiming

After removing the safety pin on the cylinder, the diffuser nozzle at the end of the hose is directed toward the fire. The trigger is squeezed to release the pressurized gas. The exiting CO₂ rapidly cools to as low as -70°C and forms a dense fog.

Angle of Application

CO₂ gas must be directed directly at the base of the flame. Caution is required as the fog effect may reduce visibility. Due to its higher density than air, the gas settles onto the burning surface and creates a smothering effect.

Use in Electrical Fires

The greatest advantage of CO₂ extinguishers is their non-conductivity and the fact that they leave no residue. For this reason, they are the first choice in environments such as switchboards, motor rooms and server systems.

Safety and Limitations

Although CO₂ fire extinguishers offer significant advantages, they must be used with caution:

• Use of CO₂ in confined and enclosed spaces can create a risk of suffocation due to rapid depletion of oxygen in the environment.
• The diffuser nozzle or hose must not be touched with bare hands; exposure to cooling near -70°C can cause frostbite to the skin.
• Before use, the pressure indicator must be checked. CO₂ cylinders typically do not have a pressure gauge; therefore, control is performed by weighing.

Carbon Dioxide (CO₂) Fire Extinguisher (Generated by Artificial Intelligence)

Design Features and Capacity Variants

CO₂ fire extinguishers typically consist of a cylindrical steel body with an internal pressure of approximately 55–60 bar. During use, the gas transitions from liquid to gaseous phase through vaporization. Instead of a pressure gauge, the fill level of CO₂ cylinders is generally verified by weighing. Common capacities are 2 kg, 5 kg, 10 kg and 30 kg.

Advantages and Limitations

Advantages:

• Leaves no residue, preventing damage to electronic devices.
• Safe for use on electrical fires.
• Suppresses fire very rapidly.

Limitations:

• Presents a risk of suffocation in enclosed and poorly ventilated areas.
• Does not provide sufficient cooling for Class A fires (solid materials).
• The metal discharge horn may become extremely cold during use and cause cold burns upon contact.

Periodic Inspection and Maintenance

CO₂ cylinders, like dry chemical powder cylinders, are subject to regular inspections and tests. According to the TS ISO 11602-2 standard:

• Inspection every six months,
• Hydrostatic test every five years,
• Refilling is mandatory after every use.

In addition, the net weight and tare weight of the device must be clearly indicated on the label, enabling users to verify the fill level by weighing.

Regulations and Mandatory Application

CO₂ extinguishers are designated as mandatory equipment in locations specified under the Regulation on Protection of Buildings Against Fire. Electrical panel rooms, UPS rooms and generator rooms fall within this scope. Additionally, supplementary CO₂ units may be installed in other areas based on the results of fire risk assessments.