Motorised pressure relief vents explained

Motorised pressure relief vents are increasingly used in environments where both safety and operational flexibility are required. While their primary function remains the same as a standard pressure relief vent, the addition of motorised control allows these vents to be used for regular, controlled venting during normal operation.

This article explains how motorised pressure relief vents work, how they differ from passive vents, and where they are typically used. It also covers their reliability during power loss, maintenance considerations, and the advantages and disadvantages to help determine when a motorised solution is the right choice.

What is a motorised pressure relief vent?

A motorised pressure relief vent is a pressure relief device that can open in two ways: automatically when a defined overpressure is reached, or actively via a motor. Motorised operation allows the vent to be opened on demand, without waiting for pressure to build up. This enables regular, controlled venting, during normal operation.

Importantly, the core safety function remains unchanged. Even if the motor or power supply fails, the vent continues to operate as a standard pressure relief vent. Overpressure alone is sufficient to open the vent, ensuring protection is maintained at all times.

How motorised vents differ from passive vents

Standard, non-motorised pressure relief vents are designed to remain closed until an overpressure event occurs and cannot be used for routine ventilation. A motorised vent bridges this gap by combining passive pressure relief with the ability to open the vent intentionally for operational, environmental, or maintenance-related venting needs.

Despite this added functionality, the fundamental operating principle remains the same for both types of vents. In an overpressure event, the vent opens purely as a result of pressure, not motor action. This means a motorised pressure relief vent provides the same passive safety response as a non-motorised vent, with the added benefit of controlled venting when required.

Applications of motorised pressure relief vents

Motorised pressure relief vents are used in environments where both safety and operational flexibility are important. Their ability to provide controlled venting, while still offering passive overpressure protection, makes them suitable for a wide range of applications.

• Industrial processes where regular or scheduled venting is needed during normal operation.
• Gas fire suppression systems, where controlled venting may be required during testing, commissioning, or maintenance of gas suppression.
• Blast mitigation environments that require passive pressure relief combined with operational flexibility.
• HVAC systems where pressure balance and periodic ventilation are important.
• Gas storage rooms to allow controlled release of air or gas without relying on overpressure events.
• Data centres and technical rooms where environmental control and safety must be maintained simultaneously.
• Battery energy storage systems (BESS) and other enclosed energy environments requiring flexible venting.

Reliability of motorised pressure relief vents

Motorised pressure relief vents are designed to maintain their safety function under all operating conditions. Even when the vent is held open by the motor for controlled venting, it continues to function as a pressure relief vent. If an overpressure event occurs, the vent responds to pressure in the same way as a passive vent.

In the event of a power failure, the motorised function is simply unavailable, but the vent itself remains fully operational. The vent automatically defaults to passive operation, ensuring that overpressure can still be safely relieved without reliance on electrical power.

The advantages and disadvantages of motorised pressure relief vents

Motorised pressure relief vents offer additional functionality compared to passive vents, primarily by enabling controlled venting during normal operation. While this added flexibility brings clear advantages, it can also introduce considerations that are not relevant for non-motorised vents. 

Understanding both helps determine whether a motorised solution is appropriate for a specific application.

Advantages

• Allows regular, controlled venting in addition to emergency pressure relief.
• Enables manual, remote, or automated operation.
• Reduces the need for manual venting procedures and associated downtime.
• Maintains full pressure relief functionality even if power or motor control is lost.
• Can be integrated with monitoring, control, or building management systems.

Disadvantages

• Higher upfront cost compared to passive pressure relief vents.
• Slightly more complex installation due to motor and power requirements.
• Requires periodic inspection and maintenance of the motor and control components.
• May not be necessary in applications where only emergency pressure relief is required.

Maintenance of motorised pressure relief vents

Motorised pressure relief vents generally require slightly more maintenance than passive vents due to the addition of motor and control components. However, the core pressure relief mechanism itself is similar. This means the safety-critical function does not introduce additional maintenance complexity compared to a passive vent.

Routine maintenance typically includes inspection of both the motorised system and the mechanical vent components. The motor, wiring, and control interface should be checked periodically to ensure reliable operation. The vent panels, seals, and hinges should be inspected for wear or damage.

It is also important to ensure the vent remains unobstructed at all times, as blockages can affect both motorised venting and passive pressure relief. Regular testing should confirm that the vent opens correctly when activated by the motor and that it responds properly to overpressure, verifying safe operation under all conditions.

Our motorised SHX-UN pressure relief vent

The SHX-UN motorised pressure relief vent combines controlled venting with reliable passive overpressure protection. It is designed primarily for inert gas fire suppression systems. It can be opened via motor for regular or scheduled venting, while still functioning as a standard pressure relief vent if power fails.

Built for industrial environments, the SHX-UN features the largest free vent area on the market, ensuring efficient pressure relief. It can be integrated with remote monitoring systems, requires minimal maintenance, and is designed for repeated operation under demanding conditions.

For chemical gas applications, two SHX-UN MOT vents can be installed in opposite directions to manage overpressure and underpressure. Installation is flexible: a wall liner is used for thick walls, or a Z-frame for thin walls and cladding.

Versatile and efficient, the SHX-UN MOT is ideal for industrial processes, fire suppression systems, and any environment needing regular venting without compromising safety.

View SHX-UN MOT