Gas Fire Suppression

Gas fire suppression systems use an appropriate extinguishing agent to suppress or extinguish a fire. Depending on the agent used, they work by reducing oxygen levels, absorbing heat or interrupting the chemical reactions that sustain combustion.

To help prevent accidental discharge, gas fire suppression systems can use a two-stage detection arrangement. This typically requires signals from detectors on two separate detection zones before the automatic release sequence is initiated. The exact configuration depends on the system design and the risks being protected against.

How a Gas Suppression System Extinguishes a Fire

When a detector activates in the first detection zone, the system enters its first alarm stage. If a detector in the second zone subsequently activates, the system can initiate the gas release sequence, including any required audible and visual warnings and a pre-discharge time delay. Once the delay has elapsed, the extinguishing agent is released, provided the system has not been inhibited or otherwise prevented from discharging.

During the activation sequence, the system uses audible and visual warnings to alert people to a possible fire. First, a detector may trigger an initial alarm. If a second detection zone confirms the fire, the system can activate a different warning and start a pre-discharge countdown. Once the countdown ends, the system releases the extinguishing agent, provided no safety control prevents discharge. The exact sequence depends on the system design.

The gas suppression control panel monitors the system and displays alarms, faults and its current operating status. Depending on the installation, the system may also include manual release controls and emergency hold or abort buttons. These controls help manage the release process and must meet the safety requirements of the installation.

Additional Benefits of Gas Fire Suppression

Gas fire suppression systems help businesses protect valuable equipment, sensitive environments and essential operations. In addition, many systems can respond automatically to a fire, helping to limit damage before it spreads.

• Clean fire suppression: Many gas extinguishing agents leave no solid or liquid residue. As a result, businesses may face less cleaning after a discharge.
• Protection for sensitive equipment: Suitable systems can protect electrical and electronic equipment without introducing water into the protected area.
• Automatic fire protection: Detection equipment can trigger a controlled response, including alarms, warning signals and gas release.
• Reduced business disruption: Effective suppression can help limit fire damage and support a faster return to normal operations.
• Flexible applications: Businesses can use suitable gas suppression systems to protect server rooms, data centres, electrical rooms and other specialist environments.

However, not every system suits every building. The right choice depends on the fire risks, room conditions, occupancy and equipment requiring protection.

Types of Gas Fire Suppression Systems

Different gas fire suppression systems use different methods to control or extinguish fires. The main options include synthetic clean agents, inert gases and carbon dioxide (CO₂). Each offers specific benefits, although installation requirements and safety considerations vary.

Synthetic Gas Fire Suppression

Synthetic gas fire suppression systems use specially developed extinguishing agents to control fires. These agents mainly work by absorbing heat or interrupting the chemical reactions that sustain combustion. One example is FM-200, which contains the agent HFC-227ea.

Many synthetic clean agents are stored as liquids under pressure. During discharge, a network of pipes and nozzles distributes the agent throughout the protected area. As a result, these systems can provide effective protection while using relatively compact cylinder storage arrangements.

Advantages of Synthetic Gas Suppression

• Compact cylinder storage: Some synthetic agents need less storage space than comparable inert gas systems.
• No extinguishing residue: Suitable clean agents leave no residue after discharge. Therefore, they can help reduce cleaning requirements.
• Rapid fire suppression: These systems deliver the required amount of extinguishing agent quickly to help control a developing fire.
• Protection for sensitive equipment: Businesses can use suitable systems in server rooms, electrical rooms and other areas containing valuable equipment.

Considerations and Limitations

• Environmental impact: HFC-based agents such as FM-200 have a high global warming potential. Therefore, businesses should check current regulations, agent availability and alternative options before selecting a system.
• Pipework design: Engineers must calculate pipe lengths, fittings and nozzle positions carefully to ensure the agent reaches the protected area effectively.
• Room integrity: Total flooding systems need an enclosure that can retain the required amount of extinguishing agent for the necessary period.
• Occupant safety: The chosen agent, discharge concentration and warning arrangements must suit the people who may enter the protected area.

Typical Applications

Synthetic clean-agent systems may suit several environments where businesses need to protect sensitive equipment without using water.

• Server rooms and data centres
• Electrical switch rooms and UPS rooms
• Communications and telecommunications rooms
• Control rooms and specialist equipment enclosures
• Archive rooms and document storage areas

Inert Gas Fire Suppression

Inert gas fire suppression systems use naturally occurring gases such as nitrogen and argon, or mixtures of these gases. Common agents include IG-01 (argon), IG-55 (argon and nitrogen) and IG-541, commonly known by the trade name INERGEN.

These systems suppress fire by reducing oxygen levels within the protected area. As a result, the fire can no longer sustain combustion. However, lower oxygen levels can also pose risks to occupants. Therefore, every installation needs suitable warning systems, evacuation arrangements and safety controls.

Advantages of Inert Gas Suppression

• Low global warming impact: Nitrogen and argon are naturally occurring atmospheric gases. Unlike HFC agents, they do not introduce high-global-warming-potential extinguishing chemicals.
• No extinguishing residue: Inert gases leave no residue, making them suitable for protecting many types of sensitive equipment.
• Flexible cylinder locations: Depending on the design, installers can position cylinders away from the protected room.
• Protection for multiple areas: Some systems use selector valves to direct gas from a shared cylinder bank to different protected spaces.
• Suitable for larger installations: Inert gas systems can provide an effective solution for larger rooms and complex sites.

Considerations and Limitations

• Cylinder storage: Inert gas systems often need more cylinder space than synthetic clean-agent systems.
• Pipework requirements: High-pressure storage and larger gas volumes can increase pipe sizes and installation requirements.
• Pressure relief: Gas discharge can change the pressure inside a room. Therefore, the design may need suitable pressure relief vents.
• Room integrity: The protected enclosure must retain the required gas concentration long enough to control the fire.
• Occupant safety: Reduced oxygen levels require careful planning for alarms, evacuation and access controls.
• System recovery: Following a discharge, the business must arrange cylinder replacement or recharging before restoring full protection.

Typical Applications

Inert gas suppression systems can protect a wide range of commercial and industrial environments. For example, businesses often consider them for larger equipment rooms and sites with several protected areas.

• Data centres and server rooms
• Electrical switch rooms and substations
• Communications and control rooms
• Archive and document storage facilities
• Specialist equipment rooms and enclosed machinery spaces

Carbon Dioxide (CO₂) Fire Suppression

Carbon dioxide fire suppression systems use CO₂ to extinguish fires, mainly by reducing the oxygen available for combustion. They also provide some cooling during discharge. Depending on the application, these systems can protect an enclosed space or target specific machinery and equipment.

CO₂ systems can offer effective protection for certain industrial hazards. However, carbon dioxide presents a serious danger to people at fire-extinguishing concentrations. Consequently, these systems need specialist design, a thorough risk assessment and strict safety measures.

Advantages of Carbon Dioxide Suppression

• Effective industrial protection: CO₂ can suppress fires involving suitable industrial machinery and equipment.
• No extinguishing residue: Carbon dioxide leaves no solid or liquid extinguishing residue after discharge.
• Local application: Some systems can direct CO₂ towards specific machinery rather than flooding an entire room.
• Specialist applications: CO₂ may offer a suitable solution for certain manufacturing processes and equipment enclosures.

Considerations and Limitations

• Serious risk to life: CO₂ at fire-extinguishing concentrations can cause unconsciousness and death. Therefore, businesses must never assume these systems are safe for occupied spaces.
• Strict safety controls: Depending on the installation, the system may need pre-discharge alarms, warning signs, time delays, isolation controls and other protective measures.
• Gas migration: CO₂ can collect in pits, low-level areas and adjoining spaces. As a result, the risk assessment must consider areas beyond the equipment receiving protection.
• Safe access: Staff and contractors need clear procedures before entering or maintaining protected equipment.
• Specialist assessment: A qualified specialist must assess the fire hazards, occupancy and operating conditions before recommending a CO₂ system.

Typical Applications

CO₂ suppression is mainly suited to carefully assessed industrial applications. In particular, it may protect machinery and equipment where other suppression methods are less suitable.

• Industrial machinery and process equipment
• Generator and engine enclosures
• Specialist electrical and mechanical equipment
• Printing and manufacturing machinery
• Selected local application and equipment protection systems

Choosing the Right Gas Fire Suppression System

Choosing a gas fire suppression system involves more than selecting an extinguishing agent. First, businesses need to consider the fire hazards, people using the building and equipment requiring protection. They should also assess room integrity, environmental requirements and ongoing maintenance needs.

SS Systems can discuss your premises and fire protection requirements. We can then help you explore suitable gas fire suppression options and identify a solution that meets your business needs.