How Pressure Relief Ports Work

Keeping Cold Rooms Equalised

Pressure changes are a normal part of operating cold rooms, freezer rooms and blast chillers. Every time a door is opened, closed, or a temperature change occurs, pressure inside the room shifts. If these pressure changes cannot equalise, they can place stress on insulated panels, damage atmospheric seals, reduce efficiency and make doors difficult to open.

The Explovent Relief Port is designed to safely equalise these pressure differences, helping protect the integrity and performance of refrigeration systems.

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Why Pressure Changes Occur In Cold Rooms

When warm air enters a refrigerated room, it rapidly cools and contracts. This reduction in air volume creates negative pressure, often referred to as a vacuum effect.

This can result in:

• Doors becoming difficult to open
• Increased stress on wall panels
• Seal damage
• Reduced energy efficiency

Conversely, temperature increases and defrost cycles can create positive pressure inside the room. Both negative pressure and over-pressure need to be relieved to maintain safe operating conditions.

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How The Explovent Relief Port Works

The Explovent Relief Port uses a bi-directional relief mechanism that allows air to move in either direction as required.

When negative pressure develops, the relief port allows air to enter the room.

When positive pressure develops, the relief port allows air to exit the room.

This continuous pressure equalisation helps maintain balanced conditions and reduces stress on the room structure.

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Internal Pressure Equalisation

Installed inside the cold room.

The internal side of the Explovent Relief Port sits within the cold room or freezer room. As pressure changes occur, the relief mechanism responds automatically, allowing pressure differences to equalise safely and consistently.

By maintaining balanced pressure, the system helps protect insulated panels, door seals and refrigeration performance.

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External Pressure Relief

Installed on the external side of the cold room panel.

The external side of the Explovent Relief Port provides a pathway for air movement when pressure equalisation is required.

As pressure builds inside the room, excess pressure can safely discharge. When a vacuum condition develops, air can enter the room to restore balance.

This bi-directional operation helps prevent pressure-related damage and operational issues.

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Protecting Cold Room Panels And Seals

Pressure differentials place significant loads on insulated panel systems.

Without effective pressure equalisation, facilities may experience:

• Panel movement and stress
• Atmospheric seal failure
• Ice buildup
• Air leakage
• Increased maintenance costs

The Explovent Relief Port helps minimise these issues by continuously managing pressure fluctuations during normal operation.

Pressure Equalisation In Blast Chillers

Blast chillers experience rapid temperature changes that can create larger pressure fluctuations than standard cold rooms.

For these applications, pressure equalisation becomes particularly important to help maintain panel integrity and reliable operation.

JAV Industries recommends approximately:

• Low Temperature Room: 1 Relief Port per 40³ m internal room volume
• Blast Chiller Room: 1 Relief Port per 20³ m internal room volume

 

Model	Size	Supply	Power	Temp Range
JAV100	100mm	220V	18W MAX	> -20°C
JAV150	150mm	220V	18W MAX	> -20°C
JAV200	200mm	220V	18W MAX	> -20°C
JAV250	250mm	220V	18W MAX	> -20°C
JAV300	300mm	220V	18W MAX	> -20°C

 

Learn More About Pressure Equalisation

Whether you're designing a new cold room, upgrading an existing freezer room or specifying a blast chiller installation, proper pressure equalisation plays an important role in protecting panels, seals and refrigeration performance.

View the Explovent Relief Port Range or contact JAV Industries on 07 3255 6377 for technical assistance.