A CO2 fire extinguisher puts out fire by displacing oxygen around the flame with limited cooling, and leaves no residue. It is used on flammable liquids and energised electrical equipment, not relied on for wood and paper fires. It is the natural choice for electrical and server rooms, and AZEIDK supplies it in 6 kg and 10 kg sizes. Its hazards are asphyxiation in confined spaces and cold burns, and its cylinder is hydrostatically tested every 5 years.
This guide covers how CO2 extinguishers work, when they are and are not the right choice, how to use them in electrical and server rooms, how to choose between 6 kg and 10 kg, user hazards, inspection and test intervals, and the Falcon Gold models in AZEIDK’s fire extinguisher range.
Key takeaways
- OSHA describes CO2 extinguishers as designed for Class B and C (electrical, US system) fires and not recommended for Class A.
- Never use one in a confined space with people present without proper respiratory protection.
- The discharge horn becomes extremely cold; touching it can cause cold burns.
- Hydrostatic test every 5 years per OSHA Table L-1 and NFPA 10, plus an annual hose conductivity test.
- Electrical and server rooms: the gas is non-conductive and leaves no residue, and NFPA 10 (2018 edition) says dry chemical units are not to be installed to protect delicate electronic equipment.
- Choosing capacity: portable 6 kg FCD6 for switch rooms, server rooms and control panels; wheeled 10 kg FCD10 for larger switch rooms, generator rooms and workshops.
In this article
- How does a CO2 fire extinguisher work?
- When should you use CO2 rather than powder?
- CO2 fire extinguisher for electrical and server rooms: when is it the right choice?
- Why is CO2 unsuitable for wood and paper fires?
- What are the hazards to the user?
- Where should CO2 not be used?
- Which Falcon Gold CO2 extinguishers does AZEIDK supply?
- How do you choose CO2 extinguisher capacity: 6 kg or 10 kg?
- How do you use a CO2 extinguisher safely?
- Common mistakes
- How often is a CO2 extinguisher hydrostatically tested?
- Frequently asked questions
- Conclusion
How does a CO2 fire extinguisher work?
CO2 is stored as a liquid under high pressure and discharges as a non-flammable gas that displaces oxygen. OSHA notes the discharge carries dry ice particles with a cooling effect. The gas disperses afterwards, leaving no residue on equipment. Falcon Gold lists 70 bar operating and 250 bar test pressure for its CO2 units, against 15/30 bar for its powder units, which is why CO2 cylinders are steel (St52 per the datasheet) and use a horn rather than a standard nozzle. The 6 kg unit discharges in 9 s or more over about 4 m, so users have seconds to aim; hands-on training matters, especially for electrical and generator room staff.
When should you use CO2 rather than powder?
| Item | CO2 | ABC powder |
|---|---|---|
| Flammable liquids | Suitable | Suitable |
| Energised electrical equipment | Suitable, no residue | Suitable, residue harms electronics |
| Wood, paper, cloth | Not recommended; re-ignition risk | Suitable |
| Server rooms and control panels | Common choice | Not preferred |
| Occupied confined spaces | Asphyxiation risk; needs respiratory protection | Does not displace oxygen |
| Hydrostatic test | Every 5 years | Every 12 years for most mild-steel shells |
Facilities often combine both: powder for general areas and CO2 near electrical and communications rooms. See our powder extinguisher guide.
CO2 fire extinguisher for electrical and server rooms: when is it the right choice?
Switch rooms, server rooms and control panels are the clearest use for CO2: the gas is non-conductive, leaves no residue and reaches into cabinets and openings. A bulletin from the Fire Equipment Manufacturers’ Association (FEMA) cites NFPA 10 (2018 edition): extinguishers protecting delicate electronic equipment are selected from types specifically listed for Class C hazards, and dry chemical extinguishers are not to be installed for that purpose. Our data centre fire protection guide notes that NFPA 75 calls for carbon dioxide or halogenated extinguishers in IT rooms, not dry powder. For the clean agent alternative, its sizes and when a fixed system is needed, see our FM-200 fire extinguisher guide.
| Room | Suitable Falcon Gold unit | Note |
|---|---|---|
| Server or telecom room | FCD6 portable at the entrance | Ventilate after discharge before re-entry |
| Electrical switch room | FCD6, or FCD10 for large rooms | Both product pages list switch rooms |
| Generator room | FCD10 wheeled | 3 m hose, 22 s discharge |
| Workshop with panels, liquids and solids | FCD10 plus an ABC powder unit for solids | Cover each hazard with the right agent |
| Room with a fixed gaseous system | FCD6 for first response | An extinguisher does not replace the fixed system |
How do you tackle a fire in a panel or server?
- Raise the alarm and identify your exit before approaching.
- Isolate power to the panel or equipment if it is safe to do so; CO2 works on energised equipment, but isolation stops re-ignition from the same source.
- Stand at the doorway and aim the horn at the source or cabinet opening, not at the smoke.
- After extinguishing, leave, close the door, ventilate before re-entry and do not restart the equipment until it has been checked.
For detection and fixed suppression in these rooms see electrical room fire protection.
Why is CO2 unsuitable for wood and paper fires?
OSHA explains that Class A fires may smoulder and re-ignite. CO2 knocks down visible flame but disperses quickly and does not cool deep into the fuel as water or foam does, so it is not adequate alone for paper archives or carton stores. To see which fires foam suits and how it compares with dry powder, read our foam fire extinguisher (AFFF) guide.
What are the hazards to the user?
Asphyxiation
OSHA states a CO2 extinguisher must never be used in a confined space with people present without proper respiratory protection. The Wormald CO2 extinguisher safety data sheet warns that high concentrations may cause asphyxiation without warning and that oxygen should be confirmed at 19.5% or more before entering a confined space where CO2 is present.
Cold burns
The same SDS warns of frostbite to skin and eyes from uncontrolled release. Hold only the handle and the insulated horn grip, and never point the horn at anyone.
After use
The SDS advises increasing ventilation, evacuating unprotected people and monitoring oxygen in confined spaces. Ventilate the room well before re-entry and watch for re-ignition.
Where should CO2 not be used?
- Small closed rooms with occupants and no ventilation or respiratory protection.
- Deep-seated solid fires, except as a support unit.
- Combustible metals, which need Class D extinguishers.
- Commercial cooking oils, which NFPA 10 assigns to Class K units alongside kitchen suppression systems.
Fixed protection of server rooms and archives relies on engineered gaseous systems, not extinguishers alone; see our clean agent comparison.
Which Falcon Gold CO2 extinguishers does AZEIDK supply?
| Item | FCD6 (portable 6 kg) | FCD10 (wheeled 10 kg) |
|---|---|---|
| Fire classes (datasheet) | B, C, E | B, C, E |
| Discharge range | 4 m | 3 m |
| Discharge time | 9 s or more | 22 s |
| Gross weight / hose | 21.3 kg; hose and horn | 3 m hose |
| Operating / test pressure | 70 / 250 bar | 70 / 250 bar |
| Temperature range | −30 to +60°C | −20 to +60°C |
| Valve | Hot-stamped brass | Hot-stamped brass |
The class letters follow European logic: E is used in catalogues for electrical equipment, while C under EN 2 means flammable gases, so confirm the class table with the supplier before approving a unit for a gas risk. Good practice is to mount the unit at or just outside the room entrance, with the exit behind the user, not deep inside a small room where gas can concentrate; the designer sets numbers and travel distances under NFPA 10, covered in our NFPA 10 guide. For all Falcon Gold types see the Falcon Gold extinguisher guide.
How do you choose CO2 extinguisher capacity: 6 kg or 10 kg?
The two CO2 capacities on AZEIDK’s Saudi site are the portable 6 kg and the wheeled 10 kg. The choice depends on room size, who will use the unit and how easily it can be moved:
| Criterion | FCD6 (6 kg) | FCD10 (10 kg) |
|---|---|---|
| Handling | Hand-carried; 21.3 kg gross | Wheeled |
| Discharge range | 4 m | 3 m with 3 m hose |
| Discharge time | 9 s or more | 22 s |
| Locations on product page | Switch rooms, server rooms, control panels | Switch rooms, generator rooms, workshops |
| Operating temperature | −30 to +60°C | −20 to +60°C |
Rule of thumb: choose FCD6 for small and medium rooms reached through a door or narrow corridor; choose FCD10 where the hazard is larger (several main panels, a generator or a workshop) and floors and aisles allow the trolley to move, since its longer discharge gives the user more time. OSHA 29 CFR 1910.157 limits travel distance from a Class B hazard area to an extinguisher to 50 ft (15.2 m) and distributes Class C units on the pattern of the Class A or B hazards present. Final numbers and travel distances on your project are set by the designer under NFPA 10 and SBC 801. If your drawings call for another size, send them to AZEIDK for review.
How do you use a CO2 extinguisher safely?
- Pull the safety pin.
- Hold the insulated horn grip and aim at the base of the fire from within range.
- Squeeze the handle and sweep at the base.
- Step back and watch the area; fire may re-ignite once the gas disperses.
Identify your exit first, and leave immediately if the fire grows or the unit empties, as OSHA advises.
Common mistakes
- Relying on CO2 alone in paper archives or carton stores.
- Discharging in a small closed room and staying inside.
- Fitting a powder unit in a server room instead of CO2.
- Holding the horn itself during discharge.
- Monthly checks by sight only, without weighing.
- Skipping the 5-year hydrostatic test because the unit was “never used”.
- Rehanging a partly discharged unit without recharge.
How often is a CO2 extinguisher hydrostatically tested?
| Task | Interval | Scope |
|---|---|---|
| Monthly inspection | Not exceeding 31 days | Location, access, fullness checked by weighing or hefting |
| Annual maintenance | Yearly | External examination by a certified technician; hose conductivity test |
| After use | Immediately | Recharge, then leak test for self-expelling units |
| Hydrostatic test | Every 5 years | By trained persons with suitable equipment; OSHA sets test pressure at 5/3 of the stamped service pressure |
See our extinguisher maintenance and refill guide. AZEIDK provides extinguisher maintenance with its own team under its maintenance contracts. The applicable NFPA 10 edition is set by SBC 801 and Civil Defense requirements, and extinguishers need a SASO certificate of conformity.
Frequently asked questions
What is the best extinguisher for a server room?
CO2: it leaves no residue and does not conduct electricity, and NFPA 10 (2018 edition) says dry chemical units are not to be installed to protect delicate electronics. Mount it at the entrance.
Should I choose a 6 kg or 10 kg CO2 extinguisher?
6 kg portable for server rooms, control panels and small rooms; 10 kg wheeled for large switch rooms, generator rooms and workshops.
Is CO2 safe on electrical equipment?
Yes. The gas is non-conductive and leaves no residue, so it suits electrical panels and server rooms.
Can I use CO2 in a small room?
With great care. Not in a confined space with people present without respiratory protection, and ventilate before re-entry.
How do I know a CO2 extinguisher is full?
By weighing or hefting it against the marked weight, as NFPA 10 requires for self-expelling units at monthly inspection.
How often is it hydrostatically tested?
Every 5 years under NFPA 10 and OSHA Table L-1.
What is the difference between CO2 and powder extinguishers?
CO2 leaves no residue and suits electrical and liquid fires; ABC powder also covers solids but leaves residue.
Conclusion
A CO2 extinguisher is a precise tool: excellent on electrical and liquid fires where no residue is acceptable, weak on solids, and dangerous in confined spaces if misused. It is the first choice for electrical and server rooms. The right size and location, user training and inspections on schedule make it a reliable part of the protection plan.
Equipping electrical or server rooms with CO2 extinguishers? Send us the room list and sizes, and we will propose suitable Falcon Gold models with datasheets and a maintenance programme. Contact the AZEIDK team
