What is the right gas suppression pressure relief vent for your system?

Choosing the right gas suppression pressure relief vent is critical to the effectiveness and safety of your gas fire suppression system. Using the wrong vent (or none at all), can lead to system failure, structural damage, and serious safety risks in critical spaces like data centers and electrical rooms.

This guide explains what to consider when selecting a gas suppression pressure relief vent, how gas type affects your choice, and why engineered pressure vent systems are far superior to relying on natural leakage of buildings. Most importantly, it introduces two purpose-designed vent solutions, the SHX-UN and DUX, that offer reliable protection across different suppression scenarios.

Why pressure relief vents matter in gas suppression systems

When a gaseous fire suppression system discharges, it rapidly changes the pressure inside a room. Without a controlled way to release that pressure, the force can damage doors, walls, ceilings, and even critical equipment. Worse, it can prevent people from opening doors or safely exiting the space.

A gas suppression pressure relief vent allows overpressure (and in some cases underpressure) to escape the room in a controlled way. This preserves room integrity, protects structural components, and ensures the suppression system performs as designed.

What about natural leakage?

In some installations, people assume the building’s natural leakage (tiny gaps, cracks, or imperfections) is enough for pressure relief venting. This is a dangerous and unreliable approach.

Here’s why natural leakage should never be used as a pressure venting solution:

• It compromises fire barriers. Any wall with holes or gaps large enough to release gas pressure may no longer qualify as a fire-rated barrier under safety codes.
• Performance is unpredictable. Airflow through natural leakage paths varies with wind, temperature, and pressure differentials. This makes it impossible to guarantee consistent gas concentration hold times to suppress a potential fire.
• It can create pressure hazards. As little as 50 pascals of pressure can make a door difficult to open. That’s a serious risk during emergency egress.
• Leakage rates change over time. What might seem like a slow, consistent leak today could look very different after structural changes, equipment installations, or simple wear and tear.

A properly designed and tested gas suppression pressure relief vent is the only reliable way for pressure venting. It ensures your fire suppression system discharges safely and effectively without compromising the building or endangering its occupants.

Understanding the type of gas used in your suppression system

Not all gaseous agents behave the same during discharge. Therefor, the type of suppression gas you use has a direct impact on vent selection.

Inert gas systems

Inert gaseous fire protection systems work with nitrogen, argon, or blends like Inergen. They suppress a fire by displacing oxygen in the room.

These gases are stored at high pressure and released gradually, but they displace a large volume of air during discharge. This results in a steady buildup of pressure inside the protected space.

Because of the high volume change, inert gas systems require vents that:

• Open at low pressure thresholds;
• Maintain performance during long-duration discharges;
• Are robust enough to handle the pressure over time.

Chemical gas systems

Chemical or halocarbon gaseous agents, like FM-200 (HFC-227ea) and Novec 1230 (FK-5-1-12) work differently. Instead of displacing oxygen, they interrupt the fire’s chemical reaction.

These systems discharge very rapidly, often within 10 seconds or less. While the volume of gas released is smaller than with inert gases, the speed of the discharge causes a sudden spike in pressure.

Vents for chemical systems must:

• React almost instantly to pressure spikes;
• Handle both overpressure and underpressure;
• Reseal effectively to maintain room integrity.