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Carbon Dioxide Fire Extinguishers (CO2) According to NFPA

 





Carbon Dioxide Agent:

Carbon dioxide is a compressed gas agent and is commonly referred to as CO2, the agent is retained as a liquid at 800 to 900 psi at temperatures below 31°C, and is self-expelling.

Matching Hazard to carbon dioxide extinguishers:

Although rated for use on Class B and C fires, it is often effectively used on small Class A fires.

How Carbon Dioxide Extinguishes Fire?

  1. Carbon dioxide prevents combustion by displacing the oxygen in the air surrounding a fire.
  2. Cooling the fuel, The rapid expansion and pressure reduction of the pressurized liquid carbon dioxide in the cylinder results in the cooling and refrigeration effect.

Advantages:

  • CO2 extinguishers don't leave a residue, a consideration that may be important in laboratories and in areas in which food is prepared or electronic equipment is present.

Disadvantages

  • CO2 extinguishers have a relatively short range because the agent is expelled in the form of a gas/snow cloud.
  • CO2 extinguishers are affected by wind or drafts.
  • If CO2 extinguishers are used in a confined or unventilated area, precautions should be taken so that people are not overcome from lack of oxygen.

Characteristics of CO2 Extinguishers:

For the various sizes, stream ranges, discharge times, temperature requirements, and ratings of carbon dioxide extinguishers available, see the below table:

CO2 Extinguisher Components:

  1. pressure cylinder, or shell
  2. siphon tube
  3. valve for releasing the agent
  4. discharge horn or horn-hose combination.

How to operate CO2 Fire Extinguisher:

  • Hold the CO2 extinguisher upright by its carrying handle, remove the locking pin, and squeeze the operating lever.
  • In smaller portable models, the discharge horn often is connected to the valve assembly by a metal tube/swing joint connector, it may be operated with one hand.
  • Larger portable models require two hands, and their discharge horns are attached to a length of hose.
  • Wheeled extinguishers have a cylinder valve with a locking ring pin, a long hose of (4 to 12 m), and a projector that consists of a horn, a long handle, and a control valve. Once the cylinder valve has been opened, the operator controls the discharge with the valve on the projector handle.


References of this article:

NFPA-10 - 2018 edition (Standard for Portable Fire Extinguishers)



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