As a building or facility owner, you may have very critical operations that rely on a data center or electrical substation which run on a very sophisticated set up of controls and electrical equipment. If something were to happen to the enclosure, such as a fire event within an electrical panel, your sensitive electrical equipment could be taken out of commission, and the fine-tuned machine that is your facility operations will come to a screeching halt!
A failure event could mean a loss in production at your plant or could mean a complete blackout of your online sales or social media systems, resulting in a loss of a million dollars a day for some businesses. Another way to look at this could be that a major exposure in your cybersecurity defense systems is now exposed, acting like an open door to malicious hackers to hijack a company’s information technology system. This could lead to a major retailer having their customer’s private data stolen, a mega corporation or government agency having their secret information (marketing plans, financial statements, defense strategies, etc.) accessed, or a major utility having their pipelines or power grids hijacked and taken for ransom.
When it comes to protecting sensitive electrical equipment, an owner may need to consider a gaseous fire suppression system as the first line of defense against a potential fire from ruining their operations.
(Source: Concept Fire Suppression LTD)
The Right Solution for the Right Application
In the fire protection world, water is king when it comes to fire suppression. Water has great cooling and heat absorption properties. It is a great solution for the majority of all fire protection applications. Depending on the system design, water can be used to effectively control fire spread and to even extinguish flame altogether. However, there are drawbacks of water based fire suppression. These drawbacks include incompatibility with electrical panels and equipment, risk of thermal shock to sensitive mechanical equipment, and water damage to a building after system discharge. Any of these drawbacks can put critical equipment out of commission and hinder an organization’s ability to operate at maximum capacity. Where water is not ideal, gaseous fire suppression can step in as the primary form of fire protection.
Applications where gaseous fire suppression systems should be considered:
- Data Centers. Protect computer server and other information technology equipment that support data and communications transfer.
- Electronic and Control Equipment Rooms. Protect sensitive electronic and control panels that provide power and logic to critical process equipment.
- Power Generation Turbines. Protect enclosures with rotating mechanical equipment that are used to generate electricity to supply the power grid.
- Critical Equipment with Sensitive Documents. Protect critical equipment that processes sensitive documents, like a paper printing press or a machine that processes customer paper checks.
- Storage of Valuable Assets. Protect storage spaces that contain important (paper) records or priceless artwork that are irreplaceable and absolutely cannot be damaged by water from a sprinkler discharge.
- Other. Other types of storage, operations, and processes where water-based fire suppression is undesirable and unfeasible.
Using gaseous fire suppression is not all advantages. There are some drawbacks and dangers to consider. Like any system, the equipment needed to run the system will take up some space. Normally, you would need a separate room to house the gas agent storage tanks and the system releasing panel. Piping will need to be routed from the tanks to the protected area, which will need careful coordination with the building architecture and other piping, ductwork, and cables/conduits serving the protected area.
(Source: Wikipedia with minor modifications)
While water combats fire by absorbing heat energy and eliminating the heat leg of the fire triangle (Figure 1), gaseous agents target the oxygen leg of the triangle (Figure 2). By filling the air space in the protected area, gaseous agents upset the oxygen concentration and push the ratios outside of the range of lower and upper limits to sustain a fire. Good news for a fire extinguishment, but this can be bad news for humans that need to breathe oxygen. If personnel become trapped in a room where a gaseous agent is discharging, this could result in personnel injury or even fatality of there is too much exposure to a gaseous agent. Luckily, multiple safeguards are built into the design and installation of these gaseous fire suppression systems to prevent injuries and fatalities.
In order for a gaseous agent to be effective, the volume of the protected space needs to be contained. The term used in the industry is “enclosure integrity,” which means all the penetrations and openings in a room or enclosure need to be sealed such that the gaseous agent cannot leak out of the room, or such that air from the outside of the room can be introduced into the space. Without enclosure integrity, the concentration of gaseous agent needed for flame extinguishment cannot be sustained.
The Pantheon of Gas Suppression
One of the most difficult things when dealing with gaseous fire suppression is choosing the right gaseous agent for the job. There is a “pantheon” of gaseous agents out there in the market, but here is a list of the most common gaseous agents as well as a couple honorable mentions.
- Halon. This is one of the oldest names when it comes to gaseous suppression agents. Halon (or Halon 1301) was once a prime choice for data center and control room protection. However, due to The Montreal Protocol on Substances that Deplete the Ozone Layer, Halon is no longer being used for new installations. A global agreement was made to phase out Halon due to its harmful ability to deplete the Earth’s ozone layer (UN Environment Programme, 2019).
Halon was very popular with the military, and existing systems that use Halon are permitted to remain in use. In fact, owners of existing halon suppression systems can purchase recycled Halon supplies. - Carbon Dioxide. Another one of the oldest names in gaseous fire suppression is carbon dioxide (CO2), which was once an excellent choice for data center and turbine enclosure protection. It was effective in displacing oxygen, and being a readily available gas in the atmosphere made CO2 an economic choice as well.
CO2 is no longer a popular choice nowadays due to the fact that exposure to minimum design concentrations of CO2 to extinguish a fire are lethal to humans. Even exposure to levels of CO2 less than minimum design concentration can cause harm to humans, such as unconsciousness, convulsions, and comas (US Environmental Protection Agency, 2000).
Another reason why CO2 is no longer popular is that CO2 demands a very high level of enclosure integrity, meaning that the enclosure being protected needs to be sealed so well that there is little to no air leakage from in or out of the enclosure. Over time, these enclosures are opened up to access equipment and put back together, but once reassembled, these enclosures never have the same level of enclosure integrity. - FM-200. In more recent years, the clean agent chemical HFC-227ea, with the trade name of FM-200, started to gain popularity as replacement of halon and carbon dioxide in data center and critical equipment type applications.
FM-200 does not deplete the ozone like Halon; however, it has been determined to have high global warming potential (3M Company, 2016). Because of this other Earth-harming characteristic, use of FM-200 has started to decline. - Inergen. Another popular solution in gas suppression is the inert gas IG-541, with the trade name of Inergen. As opposed to a chemical, Inergen is a composed of Nitrogen, Argon, and Carbon Dioxide gases, and because of its makeup of naturally occurring gases in the atmosphere, Inergen also has no global warming potential or ozone depleting potential (Johnson Controls, 2019).
One undesirable characteristic of Inergen is the use of its inert gases and its effects on the human body. At the intended design concentrations, Inergen is completely safe for human exposure and can actually enhance the human body’s ability to intake oxygen. However, when the concentration increases (which can happens minutes into system discharge) and personnel do not exit the protected space in time, exposure to the increased concentrations can cause asphyxiation as well as loss of mobility and consciousness (Fike Corporation, 2015). Customers who are aware of this risk tend to shy away from Inergen where human occupancy is expected (even for non-routine maintenance). - Novec 1230. With the demand for solution that does not harm the environment or harm humans, the clean agent chemical FK-5-1-12, with the trade name of Novec 1230. Novec 1230 has been developed to be a halon and CO2 replacement with no ozone depletion potential, very low global warming potential, and a high margin of safety to human occupants (3M Company, 2022).
For many users, the biggest benefit of Novec 1230 is the safety to personnel without the scare of exposing occupants within the space to a toxic or inhalation hazard. Novec 1230 has been tested and has been shown to be completely safe for discharge into occupied spaces. The intent is to still have occupants exit the protected space when the system discharges, but knowing that there are no adverse health effects to occupants is definitely a plus for Novec 1230. More and more Novec 1230 is becoming the prime choice for clean agent gaseous suppression. - Vortex. Although not a true gaseous fire suppression solution, it is worth a mentioning a relatively new special hazard protection solution that is a hybrid nitrogen and water mist solution known as Vortex (Victaulic Company, 2019). This suppression technology uses high pressure nitrogen to atomize water at the discharge nozzles creating a swirling fog in the space that attacks the fire triangle in two ways. The nitrogen concentrations are reduce oxygen levels and choke out the fire, and the atomized water provides cooling to remove heat from the fire.
A major benefit to Vortex is the swirling fog discharge that actually does not rely on a high level of enclosure integrity like CO2 and most clean agent / inert gas solutions. This is an ideal solution for the turbine and machinery enclosures that are plagued with inadequate seals due to the enclosure being opened up and put back together for routine maintenance.
Something to note is that the Vortex system is designed to reduce oxygen concentration in the enclosure to eliminate the fire. Depending on the application and required concentration, this may result in unsafe oxygen levels for human occupancy. These systems should be reserved to enclosures where human occupancy is rarely anticipated or to local applications where there is plenty of breathable atmosphere around the protected equipment.
NFPA Gaseous Fire Suppression Standards
With all the different fire suppression solutions out in the market, it can be confusing to know which codes and standards actually govern the design, installation, and maintenance requirements for the individual system and fire suppression agent. Here is a helpful list to navigate these requirements.
- NFPA 12, Standard on Carbon Dioxide Extinguishing Systems (Current Edition: 2022)
Although not many projects will consult this standard for a new CO2 installation, owners will find this standard helpful testing and maintaining existing CO2 systems. - NFPA 12A, Standard on Halon 1301 Fire Extinguishing Systems (Current Edition: 2022)
Just like CO2 systems, new projects will not be consulting this standard for new installation. However, owners will still find this standard helpful testing and maintaining existing Halon systems. - NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems (Current Edition: 2022)
This is THE standard when it comes to all of the clean agents (like Novec 1230 and FM-200) and inert gases (like Inergen) out in the market. New projects and existing installations with clean agents and inert gases will heavily consult this standard for design, installation, testing, and maintenance requirements. - NFPA 770, Standard on Hybrid (Water and Inert Gas) Fire-Extinguishing Systems (Current Edition: 2021)
This is new NFPA standard for the Vortex hybrid nitrogen and water mist system. The industry recognizes Vortex as an entirely different technology compared to nitrogen, a clean agent that follows NFPA 2001, and water mist, that follows NFPA 750 (Standard on Water Mist Fire Protection Systems). New projects and existing installations with Vortex will consult this standard for design, installation, testing, and maintenance requirements. - NFPA 72, National Fire Alarm and Signaling Code (Current Edition: 2022)
This is not necessarily standard on gaseous fire suppression systems, but this standard does cover all the detection, controls, and releasing requirements of the fire alarm system that serves the gaseous fire suppression system. Gaseous fire suppression systems should have the following:-
- A dedicated fire alarm control panel, usually referred to as a “fire suppression releasing control panel”. This panel is the brains of the gaseous fire suppression system and communicates status to the main building fire alarm control panel.
- A means for automatic activation by either two (2) smoke detectors or an early warning (or very early warning) air aspirating smoke detection system. If smoke is expected in the environment, the system should replace the smoke detectors with heat detectors.
- A means of manual activation by a manual release station (similar to a fire alarm pull station) located at the exit to the protected enclosure. Most systems will also have a abort switch installed as well (which really acts more like a pause button) if the system requires a countdown to discharge.
- Notification appliances (horns and strobes) to warn personnel of the countdown to discharge, if the system requires one, and to warn personnel inside and outside the space that the system has discharged.
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(Source: Fire Safety Search)
Figure 3. Example setup with agent cylinders, releasing control panel, detection, and discharge piping/nozzle.
Other Considerations
Even though gaseous fire suppression may seem like the best solution out there and the decision has been made to steer clear from a water based sprinkler system, there are regulations and design conditions that need to be considered before the next step can be taken.
- Depending on the applicable codes, standards, and design criteria that govern a particular facility and its construction projects, some of the gaseous fire suppression solutions discussed in this article may not be permitted as the sole fire suppression method. The local building code may allow a gaseous fire suppression system to be installed, but that code may still require a water-based fire sprinkler system to be installed for the protected space as well. In terms of life safety, the fire sprinkler system requirement is usually a firm requirement that cannot be removed. A simple way to think of it this…
The gaseous fire suppression is to protect the asset. A fire sprinkler system is to protect the building and to protect human life in case the fire is not contained by the gaseous fire suppression. - Something else to factor in is the age of the enclosure and its ability to keep the gaseous agent within the protected space. New construction should be easy for ensuring enclosure integrity since the room will be brand new. Existing construction undergoing renovation will be more challenging as the room construction has surely gained a few new openings since the time it was first built. Enclosures may need to be equipped with dampers and louvers (for vents) or firestop materials (for through penetrations and blank openings) to reduce the leakage rate through the shell of the enclosure to close to zero as possible. Where openings are hidden or hard to access (such as inside a cable duct bank or under a raised floor), this can be incredibly challenging and sometimes almost impossible.
In Conclusion
For owners that already have an existing gaseous fire suppression system at their facility, owners should definitely have an experienced and specialized contractor for adequate technical support. For owners considering replacement of an existing system to a newer technology or planning to install a brand new system, owners can greatly benefit from working with a life safety engineer with the specialty gaseous fire suppression experience to the design intricacies and detailed system requirements involved with gaseous fire suppression.
References:
- UN Environment Programme. (2019). The Montreal Protocol on Substances that Deplete the
Ozone Layer | Ozone Secretariat. UN Environment Programme. https://ozone.unep.org/
treaties/montreal-protocol - US Environmental Protection Agency. (2000). Carbon Dioxide as a Fire Suppressant: Examining the Risks. US Environmental Protection Agency. https://www.epa.gov/sites/default/files/2015-06/documents/co2report.pdf
- 3M Company. (2016). Fire Suppression: “Monumental” Montreal Protocol Amendment to Aggressively Phasedown Hydrofluorocarbons (HFCs). 3M. https://www.3m.com/3M/en_US/
novec-us/resources/hot-topics/full-story/?storyid=ab62c44b-45d5-4d50-b7d9-5faa6f651dad - 3M Company. (2022). 3M Novec 1230 Fire Protection Fluid. 3M. https://multimedia.3m.com/
mws/media/124688O/3m-novec-1230-fire-protection-fluid.pdf - Johnson Controls. (2017). Product Overview INERGEN Fire Suppression Systems. Ansul. https://www.ansul.com/en/us/DocMedia/F-2012091.pdf
- Victaulic Company. (2019). Victaulic Vortex Hybrid Fire Extinguishing System. Victaulic. https://www.victaulic.com/assets/uploads/literature/PB-389.pdf
