The Importance of CO2 in Fire Suppression Applications

CO2 Carbon Dioxide Safety in Fire Suppression Testing

Fire protection applications can be categorized into two basic categories: 

1) Applications that allow the use of a water-based sprinkler

2) Special hazards that require the use of other fire extinguishing agents such as CO2. (For record, special hazard applications, compromise approximately 20% of the market)

For reference, "Fire Suppression Testing" or "Fixed Fire Extinguisher Testing" is a test that is used to determine whether a fixed fire extinguisher is working correctly. In addition, this test will also ensure that the level of fire extinguishment inside is accurate.

While many factors go into fire suppression system testing, Carbon Dioxide (CO2) has long been used as a critical element in local fire applications, inerting, and total flooding environments. The inert gas goes back to the early 1920's and happens to be the only gaseous fire suppression agent used as far back as the beginning of the 1960's. 

Why Carbon Dioxide (CO2) in fire suppression?

The short answer that the NFPA 12 standards govern the use of CO2 for suppression. The more complete answer is that CO2 is effectively used as a fire extinguishing gas. Any operator of these systems will want full assurance that the fire suppression system is going to work effectively should the necessity arise. What Carbon Dioxide systems are designed to do, is displace oxygen from the designated areas, as quickly as possible, to "asphyxiate" the fire.

Typically, CO2 fire suppression systems are commonly used by the U.S. Navy, server farms, commercial shipping, voltage transformers, rolling mill processes, flammable liquid storage areas, and for industrial generator and turbine protection.

A large marine engine room system may require as much as 20,000 lbs. of carbon dioxide per system. 

What all these applications have in common however, is that they are confined within rooms where the atmosphere can be regulated. When a fire starts, high-pressure CO2 is rapidly released from cylinders. The CO2 then displaces the oxygen required for combustion, and the flames are rapidly extinguished.

The real true advantage for individuals using Carbon Dioxide and fire suppression systems is that since CO2 is an inert gas, there is little to 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. Additionally, many professionals stand by the inert gas because it is approved for suppression of Class A, B, and C hazards and is also cost effective.

To provide some perspective, we highlight Koorsen Training Center's video, where they demonstrate just what it looks like during a real CO2 fire suppression system discharge.

On the contrary to utilizing CO2, the challenge is the operators and employees near CO2 Fire Suppression Systems. This is because those individuals working around these environments must always be safe and could be at danger when dealing with the odorless, colorless, and tasteless inert gas. 

When fire-prevention systems result in the oxygen content being less than 19.5%, they are not permitted for occupied spaces by OSHA regulation in the United States. They must also be safe for first-responders after the fire has occurred.

How to prevent injury during fire suppression?

In ensuring safety, CO2Meter has worked with worldwide fire protection companies like TYCO-SimplexGrinnell, Mitsubishi Hitachi Power, and Orr Protection on the proper CO2 devices to utilize for fire suppression testing.

In order to protect individuals, facilities that use carbon dioxide follow the National Fire Protection Association or "NFPA" regulations for design, installation, and testing of CO2 systems. 

These standards state  full discharge tests and evacuation plans in order to ensure that the air be tested for normal levels before personnel can return to work.

To implement and ensure this testing, CO2Meter provides and recommends the 100% CO2 Multi Gas Sampling Data Logger. This device is the only device that meets the NFPA 12 standards.

What this device does best is that it draws gas samples into the sensing chamber allowing the sensor to take fast and accurate measurements. This ensures that the CO2 levels are within normal indoor air standards for fire suppression personnel after the tests have been implemented. 

In addition, this device also includes audible alarms, an LCD backlight screen and large display for individuals to gain an easy reading of gas concentration, temperature, relative humidity, and barometric pressure.


CO2Meter 100% CO2 Sampling Data Logger

For reference, according to ASHRAE, the recommended CO2 level in buildings should be no more than 700 parts per million (ppm) above outdoor air. Since outdoor air is approximately 400ppm, indoor CO2 levels should be no more than 1,100ppm. If the levels are higher than average, proper ventilation is required to suffice to ensure safety.

Another main concern after a fire suppression system test has been activated, is that responders should understand how long they must wait to enter into an enclosed area. To test this, after installation, a "dry run" is performed where the carbon dioxide 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 furthermore determine when it is safe to re-enter the space. Additionally, this data may be required by insurance carriers and regulated by local and national agencies. This means an individual will have to complete three tests one at each height in the discharge space OR purchase three devices to measure the different heights during a single test for efficacy. 

In addition, some regulatory agencies may also require an oxygen depletion test in order to validate the absence of oxygen in the space. These specific tests can be required as a back-up to the initial CO2 test and require other gases like Argon or Nitrogen to be used as a suppressant. For these circumstances, CO2Meter provides a 0-25% Multi Gas Sampling Data Logger to measure oxygen depletion.

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 having a multi-gas sampling data logger, such as the CM-1000, in order to meet the NFPA requirements and gain peace of mind by utilizing the data logging capabilities and recording test results for further analysis and reporting.

While currently, the NFPA has not expanded its requirements surrounding CO2 fire suppression testing, additional revisions may arise where the use of a fixed CO2 monitor may be needed.

Should you have any questions regarding what device is best suited for your needs, the team at CO2Meter would be happy to assist and walk you through our devices most commonly used across the field. 

For more information on Fire Suppression Testing and CO2 Safety Devices, speak to an expert at

Older Post Newer Post