Pressure venting for inert gas fire suppression systems
Note: This page covers pressure relief vents for inert gas fire suppression systems.
If you’re unsure whether your system uses inert or chemical gas, start with our Choose Your Vent Guide to find the right solution.
An inert gas fire suppression system offers highly effective fire protection for critical environments and electronic equipment, without leaving any residue or causing damage to sensitive equipment. These systems are widely used for electronic applications, like in data centers, control rooms, but also in archives and art galleries where asset protection matters most.
But while inert gasses are clean and avoid damaging equipment, its discharge creates a rapid pressure increase in the protected room. Without a properly designed pressure relief solution, this overpressure can compromise the structural integrity of walls, ceilings, doors, or the suppression system itself.
On this page, you’ll learn how inert gas suppression systems work, why pressure relief is essential, how they differ from chemical gas suppression systems, and how to ensure your space stays protected during discharge.
Not sure which gas suppression system you have? Check our page on "What is the right gas suppression pressure relief vent for your system?"
What is an inert gas fire suppression system?
An inert fire suppression system is a gaseous fire suppression system, using naturally occurring gases, also called clean agents, to extinguish fires by displacing oxygen in the protected area. Instead of using chemicals or water, these systems lower the oxygen concentration to a level where combustion is no longer possible (typically around 12.5%), while still being safe for short-term human exposure in occupied spaces.
Because inert gases leave no residue, don’t cause corrosion, and don’t require clean-up, inert gas fire suppression systems help reduce downtime after an incident. These systems are ideal for environments that house sensitive, mission-critical or electrical equipment. Typical applications are:
- Data centers
- Telecommunication hubs
- Archive rooms and museums
- Electrical cabinets and switchgear rooms
- Control rooms in industrial facilities
- Art galleries
- Machinery spaces
- Medical facilities
- Nuclear facilities
- Military installations
- Financial centers
- Telecommunication centers
- Wind turbines and power plants
- Offshore platforms
- Pharmaceutical industry
Common inert gases
In clean agent fire suppression systems, the following inert gas agents can be used:
- Nitrogen (IG-100)
- Argon (IG-01)
- Nitrogen/Argon blend (IG-55)
- Nitrogen/Argon/CO₂ blend (IG-541)
- Carbon Dioxide (CO₂)
These gases are stored under high pressure in cylinders and released quickly into the room when the system activates. While safe for equipment, this rapid discharge introduces a different kind of risk: overpressure.
What happens when inert gases discharge?
When an inert gas fire suppression system activates, it releases a large volume of gas into the protected space within seconds. This is a critical part of the suppression process, as the gas needs to flood the room quickly to lower the oxygen level before the fire can spread.
The discharge of an inert gas into a room aims to add up to 50% volume to the air. If the room were hermetically sealed, then this could theoretically produce pressure of around 50,000 pascals. In reality, a room always has some natural leakage, so the pressure would be nowhere near this level. However, it would still pose a serious risk of damage to the structure, especially in the first 0.25 to 2 seconds of discharge.
So, this rapid gas expansion brings a sudden and significant rise in pressure inside the room. If there’s no way for the pressure to escape, walls can flex, ceilings can lift, doors can blow open or bend, and sealed penetrations can fail, compromising the room’s integrity.
Once room integrity is lost, the gas concentration may not remain high enough to suppress the fire effectively, defeating the purpose of the system and putting both equipment and safety at risk. This is why pressure relief isn’t optional—it’s a fundamental part of safe and effective inert gas system design.
What is pressure relief?
Pressure relief is the controlled release of air or gas from a room to prevent dangerous overpressure during a system discharge. In the context of clean agent systems, this means giving the expanding gas a safe path out—without compromising the room's ability to contain the suppression agent.
This is typically achieved using pressure relief vents. These are specialized devices installed in walls, ceilings, or ducts that open automatically when the internal pressure rises beyond a set threshold. Once the pressure normalizes, the vent closes to help maintain room integrity.
Key features of pressure relief systems for inert gas:
Proper venting ensures the room stays structurally intact while also preserving the gas concentration needed to suppress the fire effectively. Key features of pressure relief systems for inert gas are:
- Fast response. Vents must open quickly enough to match the rapid pressure rise during discharge.
- Leak-tight seal. When not in use, the vent must remain fully closed to maintain the room’s airtightness.
- Directional control. Many systems are designed to relieve pressure in only one direction so that no unwanted airflow enters the room.
- Durability. Vents must withstand repeated discharges, environmental stress, and, in some cases, corrosive conditions.
Choosing the right venting solution for inert gas fire suppression systems
Not all pressure relief vents are created equal—especially when it comes to inert gas systems. Because of the high-pressure, high-volume nature of these discharges, your venting solution needs to be designed specifically to handle the unique demands of inert gases like IG-55, IG-541, or IG-100.
What to consider when selecting a vent:
Choosing the right vent for clean agent fire suppression systems isn’t just a matter of size or placement. It’s about performance under pressure. To protect the room and ensure the system works as intended, here are the most important factors to consider:
- Speed of pressure buildup. Inert gas discharges can cause pressure to rise within seconds. The vent must react immediately to avoid structural damage—delayed response can mean the pressure peak is already past by the time the vent opens.
- Room size and enclosure strength. Larger rooms or weaker structures may require more venting area or lower opening thresholds.
- Opening pressure. The vent must open at the correct set pressure—high enough to stay sealed under normal conditions, but low enough to activate before damage occurs.
- Closing mechanism. Once pressure is relieved, the vent must reseal to help maintain room integrity and prevent smoke or debris from entering.
- Installation constraints. Placement, airflow direction, and sealing are all critical to ensuring the vent functions correctly.
Working with a properly sized, reliable vent ensures your suppression system operates safely and that your protected space remains intact during and after discharge.
SHX-UN: Pressure relief vent designed for inert gas fire suppression systems
The Amventco SHX Inert Gas Pressure Vent has been specially designed to give the best pressure relief for its size in the world. It is still the only pressure vent that is built and certified to the AFP/LPG/BRE live discharge tests of 2008. Proving that it not only gives the best pressure venting operation among other vents, but also that this 3rd party verification testing offers real proof of its claimed operational capabilities.
The SHX-UN features a lightweight, responsive mechanism that opens instantly when pressure rises and closes securely once pressure is stabilized—preserving room integrity at every stage.
Key features of the SHX-UN
- Designed for high-volume gas discharge
- Single-direction
- Adjustable opening pressure settings
- Leak-tight seal when closed
- Robust construction for repeated use
- 4-hour fire rated
The SHX-UN is used in data centers, control rooms, electrical cabinets, and other mission-critical environments where inert gas suppression systems are installed.
Vent sizing
Sizing of the vents for a risk should be derived and confirmed from either the gas supplier's calculations or from an integrity test. However, for a rough estimate purpose, please refer to the following charts.
Vent sizing for inert gases with regulated valve
Vent sizing for inert gases with standard valve
Get in touch
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