In a nutshell, Carbon Dioxide (CO2) is an excellent fire suppression agent and is used in local fire applications, inerting and total flooding environments.
Why is Carbon Dioxide (CO2) so important in fire suppression, you might ask?
Carbon dioxide is effectively used as a fire extinguishing gas. CO2 Fire Suppression Systems are commonly seen in server farms, voltage transformer rooms, flammable liquid storage areas, and for industrial generator and turbine protection.
What all these applications have in common is that they are confined within rooms where the atmosphere can be regulated. When a fire starts, high-pressure CO2 is released from cylinders. The CO2 displaces the oxygen required for combustion, and the flames are quickly extinguished.
The main advantages of CO2 and Fire Suppression Systems is that since CO2 is an inert gas there is no clean-up beyond the actual fire.
Unlike water or foaming agents, CO2 will not harm any of the components. Therefore, cleanup is limited to the fire damage only. In addition, CO2 is effective on a wide range of flammable and combustible materials. Primarily many key industry leaders stand by CO2 Fire Suppression Systems also, for their ease of use, minimal components, reliability, and cost effectiveness.
In comparison however, the sole challenge facing the design of a CO2 Fire Suppression System, is that the personnel working in and near the environment must always be safe.
Fire-prevention systems which result in the oxygen content being less than 19.5% are not permitted for occupied spaces by federal regulation (OSHA) in the United States. They must also be safe for first-responders after the fire has occurred.
In ensuring safety, CO2Meter has worked with worldwide fire protection companies like TYCO-SimplexGrinnell and UTC-Chematron on CO2 fire suppression.
For example, to test CO2 Fire Suppression Systems for possible leakage, we recommend our 100% CO2 Sampling Data Logger. By attaching a length of tubing, the portable unit can be run in real-time along pipe connections and valves even in hard-to-reach locations in order to pinpoint the leaks. Even a small variance in the CO2 level can be read to trigger an alarm.
Immediately after a CO2 Fire Suppression System has been activated, another challenge occurs. First-responders must know how long they must wait before they can enter the enclosed area. To test this, after installation a “dry run” is performed where CO2 levels are tested over time at several locations simultaneously.
By measuring the CO2 levels both vertically and horizontally over time, the installer can draw a 3-dimensional map of the affected area, and can determine when it is safe to reenter. In addition, this information may be required by insurance carriers and regulated by local and national agencies.
NFPA 2001 requires that a minimum, 85% of the initial agent concentration must remain at the hold time (at the elevation of highest combustibles). ISO 14520 does not provide such guidance but does specify the applicable range of the model used to be 50% to 100% agent remaining at the hold time.
While some companies have hard-wired CO2 detection systems that are tested annually, it is not uncommon for system validation to be done by the fire prevention system contractor. For this purpose, we recommend our 100% CO2 Sampling Data Logger. This device not only meets the portability requirements, but with the built-in data logger it can record test results for later analysis and reporting.
In addition to monitoring CO2 only, we are getting more requests for a similar device that measures CO2 and oxygen levels simultaneously. Currently the specification of oxygen measurement to replace CO2 measurement has not been made. However, we have developed a wall-mounted 100% CO2 and 25% Oxygen Monitor and Data Logger that is well suited for this purpose.
“NFPA 2001: Standard on clean agent fire extinguishing systems," National Fire Protection Association, Quincy, MA, Annex C, 2008
“ISO 14520-1: Gaseous fire extinguishing systems - physical properties and system design – part 1: general requirements," International Standards Organization, Geneva, Switzerland, Annex E, 2006.
“A Modified Hold Time Model for Total Flooding Fire Suppression,” Fire Safety Journal, Vol. 45 (1), 12-20, 2010.
“Hypoxic Air for Fire Prevention,” Wikipedia.