Upgrading Co2 Suppression

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Contributor: James Bouche, Project Manager of F.E. Moran Special Hazard Systems
Writer:  Sarah Block, Marketing Director of The Moran Group

Fire sprinklers are necessary to mitigate property damage from fire. The difficulty comes into play when the space you need to protect is water sensitive. Either it can damage the equipment held in the space or the equipment could react adversely to water. To mitigate any potential issues, sensitive spaces can utilize Co2 suppression that can extinguish a fire without water. While this seems ideal, there are potential health concerns with the use of Co2. Because of this, the National Fire Protection Association (NFPA) wrote an addendum to NFPA 12, requiring life safety additions to any new and existing Co2 fire protection systems.

Uses for Co2 suppression

Protecting areas with delicate equipment from fire can be difficult. There is a vast array of plant areas that have equipment that can be damaged or react adversely to water-based suppression:
• Power plants - turbine generator enclosures, transformer vaults, hazardous material storage rooms, and battery storage rooms.
• Aluminum rolling mill plants - mill roll stacks, bearings/oil hose connections, fume hoods, coilers, and oil pits.
• Cement plants - dust collection cyclones and bag houses.

These are the applications where carbon dioxide suppression is best.

The carbon dioxide floods the area and displaces the oxygen. A fire needs three elements to stay alive: oxygen, fuel, and an ignition source. By removing the oxygen, the carbon dioxide extinguishes the fire. While this is quite effective, and leaves no damage behind, it is hazardous to humans - so much so that in 2005 NFPA 12 added a section to minimize the potential for human casualties caused by carbon dioxide poisoning. This addition effected not only future Co2 suppression, but also existing, requiring a retrofit to meet new requirements. While this addition was implemented on August 7, 2006, there are still many plants that are not up to code on this life safety addition. OSHA standard, 29 CFR 1910.159, complements NFPA 12's update, protecting employees from possible illness, injury, or death from a fire suppression system. Click here to read the full standard.

Symptoms of Co2 Poisoning

Carbon dioxide is not often thought of as a silent killer. It is added to soft drinks after all. However, in concentration of 10% or greater, it can easily cause illness and/or death.


Carbon dioxide poisoning can bring on symptoms such as deeper or labored breathing, twitching muscles, increased blood pressure, headache, increased pulse rate, eye and ear injury, loss of judgment, loss of consciousness, and death is possible as well.

Safety Regulations Introduced for NFPA 12, Section 4.3

To protect lives from CO2 fire suppressants, NFPA added section 4.3 to NFPA 12 to include life safety. The following measures must be included in carbon dioxide fire protection. Without these modifications, the fire protection system will not pass inspection and lack NFPA and OSHA compliance.
• Any personnel who enter a space protected by a carbon dioxide fire suppression system (or a space adjacent to a carbon dioxide fire suppression system where CO2 could migrate after a discharge) must be warned of the hazard and trained on safety evacuation procedures.
• Oil of Wintergreen must be added to the carbon dioxide to give it a distinctive smell and warn personnel of carbon dioxide discharge. Personnel need to be trained to notice the smell and evacuate when the smell is detected.
• Automatic carbon dioxide alarms need to be installed with a visual and audio element.
• Confined space procedures for areas that have carbon dioxide suppression must be established and enforced.
• Staff needs to be trained on the safety risks of carbon dioxide.
• Lockout valves are required on all carbon dioxide systems. The exception is if the space is too small for people to enter. However, if that space would allow seepage and the carbon dioxide to migrate from that confined space, then lockout valves do need to be added whether a person could fit in the space or not. In addition, a service disconnect cannot replace a lockout valve.

Without the NFPA 12 update, plants will fail inspection for not being compliant and will not meet OSHA regulations. For plants that have Co2 suppression systems and have not yet done the NFPA 12, Section 4.3 update, contact a qualified fire sprinkler contractor to ensure code compliancy.

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