When most people think about fire protection in a building, fire sprinkler systems immediately come to mind. Sprinkler systems have long been used to protect buildings and the people that use them. However, sprinkler systems are designed to protect the building, not its contents. And, in many settings, they can be a very costly form of fire protection because of the damage that water can do and the clean-up required after they are used. Clean agent fire suppression systems are an ideal supplement to sprinkler systems to protect any type of assets that could be damaged by water.
Clean agent fire suppression systems disperse an inert gas or halocarbon gases to suppress a fire in its incipient stage before reaching the flame/heat stage that would activate the fire sprinkler system. The clean agent systems do not create a health risk for people, they are highly effective, electrically non conducting and leave no residue upon evaporation.
While clean agent systems are rarely required by building or fire codes, businesses and other institutions and organizations are increasingly turning to clean agent fire suppression as a more effective way to protect assets such as:
- Computer systems including servers, and other electrical components
- Telecommunications systems
- Record/file repositories and libraries – anything with paper that must be protected
- Digital data repositories
- Cultural assets such as historical buildings, museums, and artwork
- Flammable liquid storage for which sprinkler systems may not provide proper protection
- Subfloors with critical building infrastructure that can be damaged with exposure to water
- Laboratory and medical equipment
The three most common clean agents on the market today are Inert gas (Inergen, Nitrogen, Argonite),3M™ Novec™ 1230 Fire Protection Fluid, and FM-200, which has been a mainstay of fire suppression systems for more than 20 years. This article provides a comparison of these three popular clean agents to help you decide which might be best for your needs.
How Clean Agents Work
Novec 1230 fluid and FM-200 are clean agent fire suppression compounds made of synthetic chemicals in liquid form and are converted to gas in the discharge process. Both work to extinguish fire and prevent re-ignition by removing the necessary elements of combustion – heat. Unlike Novec 1230 fluid and FM-200, Inert is a gaseous clean agent made up of a mixture of various inert type gases. Inert gas systems work by reducing the oxygen in the space to below that required for combustion.
Clean agents are stored in cylinders and are discharged through a fixed piping system at concentrations calculated based on the area they are intended to protect. All three agents,Inert, Novec 1230 fluid, and FM-200 extinguish Class A, B, and C fires, are electrically non-conductive, and will not short-out electronic equipment or thermally shock delicate circuitry. The table below provides some general information for each clean agent.
| Inert Gas | Novec 1230 Fluid | FM-200 | |
| Type of Compound | A mixture of the inert gases: nitrogen, argon, and carbon dioxide (CO2) | A fluorinated ketone containing carbon, fluorine, and oxygen | A hydrofluorocarbon (HFC) compound containing hydrogen, fluorine, and carbon |
|
Storage |
Stored as a gas | Stored as a liquid | Stored as a liquefied compressed gas |
| Discharge Time | 60 seconds | 10 seconds | 10 seconds |
| Clean Up | None | None | None |
Logistical Considerations
When choosing a clean agent fire suppression system, the logistics of the space you are trying to protect is an important consideration. All three of these systems store the clean agent in pressurized cylinders. But, the quantity of suppression agent they can hold depends on the type of agent they use.
Inerts are stored as a gas and discharge as a gas, which requires more agent than halocarbon clean agents, Inert systems will require more cylinders – and more space to store them in – than Novec 1230 fluid and FM-200, which are stored as liquefied compressed gas. Inert gas systems, can be located further away the protected space due to the pressure of each cylinder. Novec 1230 fluid and FM-200 generally must be within or close to the protected space.
In addition to the amount of space required, you also have to consider where that space has to be located relative to the area to be protected space. This is due to how the halocarbon agents converts the liquid into gas as it flows through the system.
With FM-200 and Novec 1230 fluid systems, the clean agent is stored as compressed liquid inside the cylinder and is pressurized with dry nitrogen to push the clean agent through the piping system. It is the friction created as the liquid flows under pressure through the discharge piping that turns it into a gas. Compressed liquids don’t flow as well as inert gases, and the pressure at which they flow through the pipe is lower than that of inert gases. As a result, the length of the discharge piping for the FM-200 and Novec systems is more limited than that of the Inert gas systems.
In contrast, the higher pressure in inert gas systems through the discharge piping system and over greater distances. So, while the Inert gas systems requires more cylinders, they can be located further away from the room to be protected. Another advantage of the Inert gas system is that it can be used to protect multiple areas through the use of selector valves, which can also reduce the number of cylinders needed for multiple spaces.
The table below summarizes some of the key differences between these systems that should be considered when choosing a clean agent fire suppression system for your business.
| Inert Gas Systems | Novec 1230 Fluid and FM-200 Systems | |
| Proximity of Cylinders to Protected Space | Can be located further away | Must be located within or very near the space to be protected |
|
Number of Cylinders |
Requires more cylinders for the same area protected than Novec 1230 and FM-200 – more storage space but can protect more than one area using selector valves | Requires fewer cylinders for same amount of space to be protected – less storage space than Inert gas systems and also less piping required |
| Weight of Cylinders | Pressure only, no need to weigh cylinders but pressure must be checked on each cylinder with a calibrated gauge | Agent containers weight and pressure must be checked. Could require removing containers and placing on scale |
| Ventilation Requirements | Room pressure venting may be required | Typically no special ventilation required |
Potential Health Effects of Clean Agents
The “clean” in fire suppression clean agents means that they are safe to use in an occupied area and contain no substances that are toxic to humans.
The likelihood of exposure to the clean agent in the fire suppression system is minimal if the proper warning and alarm systems are in place to give occupants sufficient time to evacuate. With ample training for personnel and understanding of how the clean agent systems operates, the risks are minimal.
But, even with clean agents, too much of a good thing can be dangerous. Novec 1230, FM-200 and Inert gas systems all have concentration limitations. Proper design flow calculations are necessary to ensure the amount of agent is discharged for the cubic volume will result in a safe concentration for whatever agent you’re using.
Testing and certification laboratories assign different types of values to indicate the relative safety of clean agents and to guide proper engineering of the systems that use them. The table below compares Inerts, FM-200, and Novec 1230 fluid in the following terms:
- Design Concentration – Concentration of agent in the protected space that are safe for occupied spaces to extinguish Class A, B or C type fires.
- The No Observable Adverse Effects Level (NOAEL) – The highest concentration at which adverse toxilogical or psychological effect has been observed.
- Safety Margin – The margin of safety for a clean agent is calculated based on the NOAEL and the use concentration. The less agent you have to use (design concentration) relative to the concentration at which adverse effects are observed
- Lowest Observable Adverse Effect Level (LOEAL), The lowest concentration at which an adverse psychological or toxicological effects have been observed.
| Inert Gas | Novec 1230 Fluid | FM-200 | |
| Use Concentration | 34.2-42% | 4.0-6.0% | 6.7-8.7% |
|
No Observable Adverse Effects Level (NOAEL) |
43% | 10% | 9% |
Environmental Considerations
Historically, the main environmental concern with clean agent fire suppression systems has been their effect on the Earth’s ozone layer. When the problem of ozone depletion was discovered in 1985, the fire safety industry began looking for alternatives to the Halon-based compounds used in clean agent fire suppression systems at the time.
Halon is a Monobrotrifluoromethane with very high ozone depletion properties. Its production was banned in 1994 under the Clean Air Act. While it is still legal to purchase and use recycled Halon, eventually, the diminishing supply will require businesses with halon-based fire suppression systems to replace their Halon systems with systems that use readily available alternatives such as Inert gas, Novec 1230 fluid and FM-200.
FM-200 – a hydrofluorocarbon (HFC) – was the first replacement for Halon that promised no impacts to the ozone layer. It is important to note that there are no regulations against using FM-200. It is still manufactured and widely used in clean agent fire suppression systems. However, the increasing concern over global warming has given rise to newer alternatives such as Novec 1230 fluid – the first clean agent on the market to boast no impact to the ozone layer or global warming – and Inerts.
| Inert Gas | Novec 1230 Fluid | FM-200 | |
| Ozone Depletion Potential (ODP) | None | None | None |
|
Global Warming Potential (GWP) |
None | 1 (equivalent to that of carbon dioxide) | 3500 |
|
Atmospheric Lifetime (years) |
None | 0.014 | 36.5 |
Clean Agent Fire Suppression Systems Maintenance
The NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems requires that your system as a whole must be inspected annually. The cylinders must be checked for weight and/or pressure every six months to ensure they have the required quantity of clean agent and that they are properly pressurized.
Whether you are contemplating an upgrade to your current fire protection system or are already enjoying the peace of mind that a clean agent fire suppression system provides, Koorsen can assist. Koorsen’s fire suppression experts can answer all your questions about clean agent fire suppression systems and can design a cost effective system that will meet your unique needs. Call us or contact online below to talk with a Koorsen Fire Suppression expert today.
