CO2 is a highly effective fire-suppressing agent with a diverse range of applications.
As such, its use in fire suppression systems and extinguishers has been popular for some time.
Yet, while CO2 fire suppression systems have become more common, the proper use of these systems, as well as knowledge of the risks, has remained dangerously limited, even among those relying on them.
To help better educate and protect those with and interested in CO2 suppression systems, this post will answer all the basic questions about CO2 fire suppression systems.
Are CO2 Fire Suppression Systems Dangerous?
The straight answer is yes.
CO2 suppression systems can be incredibly dangerous when those working near them are not properly educated on how the system works and what to do when it activates.
The reason is this:
CO2 is an invisible, odorless, and tasteless gas. It only takes CO2 levels to be at 7.5% of the air to asphyxiate (suffocate) a person. As a person is exposed, their lungs breathe more and more deeply, very quickly absorbing more and more CO2.
At CO2 levels of 30% concentration or above, it takes only moments before a person suffocates to death.
The average CO2 fire suppression system protecting an enclosed room starts at 34% CO2 levels. CO2 suppression systems that protect areas with high voltage begin at concentration levels of 50% CO2. Systems protecting areas with the risk of deep-seated fires begin at 65%, and dust collectors in HVAC systems are protected by 75% CO2 concentrations.
CO2 is a cheap, plentiful, highly-effective, and flexible fire suppression agent, but it is NOT a life-safety agent. As you can see from the above, being present when these systems discharge is extremely dangerous. Even if a person is not exposed to the point of fatality, the effects of CO2 on them can still be very harmful.
So, why use these systems at all rather than a clean agent or other systems?
Because there are specific applications where another forms of fire suppression will not work. When people are properly trained, and proper life-safety devices are put in place, CO2 suppression systems can still be safe to use.
Where are CO2 Suppression Systems Implemented?
CO2 fire suppression systems are commonly used in manufacturing and production facilities. They are especially relied on in facilities with dry, high-voltage electrical rooms, trenches, storage vaults, and dust collectors.
All of these types of areas have the potential for what is called deep-seated fires – fires that can slowly smolder over a long period before finally igniting and quickly becoming an overwhelming fire.
There are four basic CO2 system designs depending on the setting and need:
- Systems protecting room enclosures with room integrity (no openings), like a storage room storing flammable liquids. These systems dump CO2 into the enclosure at an effective concentration for the contents inside, often starting at 34% concentration.
- Systems protecting areas with the potential for deep-seated fires use a total flood system with concentration levels typically starting around 50%. Total flood systems can be used in open rooms, where room integrity cannot be attained. These are often applied to dry electrical or high-voltage areas.
- Local application rate-by-area system for non-contained equipment, such as conveyor belts, dip tanks, rolling mills, etc. With these systems, the CO2 nozzle dumps the CO2 onto the equipment being used. The CO2 will escape to surrounding areas, putting those working nearby at risk if they are unaware.
- Local application rate-by-volume is for a piece of 3D equipment (rather than equipment with flat, open surfaces), such as a generator. It works similarly to the local application with rate-by-area but is a little trickier to design.
Furthermore, there are both high-pressure and low-pressure systems, depending on your storage needs. Low-pressure systems are typically implemented for larger systems where 4,000 pounds or more of CO2 need to be stored. These systems allow for valve control that can shut off or control the flow of CO2 mid-discharge.
High-pressure systems are usually for smaller applications. Once their valves open to discharge the CO2, there is no stopping the discharge or closing the valve.
Why is CO2 Used Instead of a Clean Agent?
Clean agents have come a long way and have done much to make fire suppression safer. In general, if a clean agent can be effectively used in lieu of CO2, then the NFPA and AHJs will regulate it as such.
However, there are still applications that require CO2. Clean agents are not good at handling slow smoldering, deep-seated fires. They simply are not fast and strong enough.
Similarly, in high-voltage areas where the electricity can not be shut off, CO2 is far more effective at suppressing the fire and keeping it suppressed, despite the continuous flow of electricity.
Finally, in spaces where room integrity cannot be maintained, CO2 can still be used effectively. Clean agents are only effective in enclosures with absolutely no openings (no missing ceiling tiles, no unclosed holes in the walls, no open doors or poorly sealed windows, etc.).
How are People Warned if CO2 is Discharged?
So, if CO2 fire suppression systems are necessary for numerous settings and are harmful to human life, how are people warned and protected from these systems?
Fortunately, there are now many life safety devices and procedures that can and should be implemented to keep people safe when CO2 suppression systems are in use.
If you have a total flood CO2 system protecting an occupiable enclosure, then you are required to have pneumatic time delays, sirens, supervised lock-out valves, and safety maintenance switches. Following are brief descriptions of each:
- Pneumatic time delays: the time delay does exactly what it sounds like – it delays the release of the CO2. The delay is initiated when the CO2 suppression system is activated and delays the release of the CO2 for approximately 30 to 60 seconds to allow personnel in the area to evacuate.
- Pneumatic siren: the siren is activated as soon as Co2 system has been activated and sounds a loud warning to those in the area to alert them to the activated CO2 system. The siren will continue through the time delay and the discharge of the CO2 until it is completely discharged. Once all of the CO2 is discharged, then the siren will switch off.
- Pneumatic Odorizer: In some designs, for example areas that Co2 might drift or could be located in during and after a discharge, the smell of wintergreen will be used. There is a small ampule with a liquid, once the Co2 discharges, the pressure from the Co2 will break the glass, the liquid mixes with the C02 to give that wintergreen smell.
- Warning Signs: Warning signs need to be posted wherever someone could be exposed to C02. Depending on the application, there are several different warning signs that maybe needed.
- Supervised lock-out valve: this lock-out valve can be used whenever maintenance is being performed on the system to prevent accidental CO2 discharge. To activate the lock-out valve, personnel or technicians simply turn a lever that blocks the line between the CO2 cylinder and the discharge nozzle. These valves do not prevent the CO2 from discharging, but they do prevent it from dumping out of the pipe into the surrounding area.
- Safety maintenance switches: these switches allow personnel or technicians to electrically disable the system during maintenance to help prevent accidental discharge.
For local application CO2 fire suppression systems, such as those used on conveyor belts, not as many safety devices are required. However, because the amount of CO2 released into the area could still be harmful and even fatal, the use of supervised lock-out valves and a pneumatic wintergreen odorizer are ideal, along with proper warning signage:
- Pneumatic wintergreen odorizer: because CO2 is odorless, the odorizer is added to the CO2 tank and injects a wintergreen scent into the CO2 agent as it either leaks or is discharged from the system. If the personnel working around the system are properly trained, they should know that if they smell wintergreen, it is a sign of CO2 in the air and that they should evacuate immediately.
- Warning signage: the NPFA does require that proper warning signs be placed in visible areas in and around all spaces protected by a CO2 suppression system. These signs include a one-lunged man's image and have information warning about the risk of injury and death potentially caused by CO2. It warns individuals not to enter a protected space when the system is activated.
If these life-safety devices are properly implemented, there is little reason those working in or near areas protected by a CO2 system should experience harm.
But more than just implementing these devices, personnel should also be properly trained.
Is Training Required for Those Working Near CO2 Suppression Systems?
YES, ALL personnel should be trained in the dangers and how the Co2 system functions and where the potential of low-lying areas that Co2 could migrate too.
To ensure that your personnel remains safe, you should implement the following steps and training:
- Inform everyone working around the CO2 system that it is there and to recognize the effects of CO2 exposure:
- Chest pain
- Blurred vision
- Shortness of breath
- Train them on your system's life-safety devices so that they understand what the sirens, signs, and wintergreen smells mean.
- Develop a standing operating procedure and train your personnel on it. This should include what each person is to do in the event of a system discharge.
- Train the designated personnel member(s) on how to operate the system, including using the supervised lockout valve.
If you are struggling to develop an operating procedure and/or sufficiently train your personnel on your CO2 fire suppression system, then call your local Koorsen Fire & Security branch. They can send a trainer out to your location to educate your team on how to handle your system properly, what the warning signs are of CO2 discharge and exposure, and give you guidelines to create your procedures.
Unanswered Questions About CO2 Fire Suppression Systems?
If you still have questions or concerns regarding a CO2 suppression system, contact Koorsen Fire & Security today.
Our team can help answer any questions you may have and can provide proper training, maintenance, inspection, and even installation on the fire suppression system you have or may be interested in.
Call today or visit us online.