What is the Working Principle of a Breather Valve?

In pressurized storage systems, breather valves play an essential role in ensuring safe and efficient operation. Often mounted on fixed-roof storage tanks, these devices are specifically designed to manage internal pressure fluctuations and protect the structural integrity of storage tanks, making them useful for many systems. In this article, we will explore the function, operation, and protective benefits of breather valves in depth, so be sure to read on to learn more.

What Is a Breather Valve?

As already discussed, a breather valve is a specialized venting device installed on the top of a storage tank, its core purpose being to regulate internal pressure by allowing air or vapors to enter or exit the tank as needed. These devices are typically available in three configurations, which are:

• Pressure-Only Valves
• Vacuum-Only Valves
• Combination Pressure and Vacuum Valves

Each configuration has features that mitigate risks like tank collapse, rupture, or excessive vapor loss, making it important to be familiar with the basics of each.

Why Are Breather Valves Necessary?

Storage tanks constantly face pressure variations due to processes like liquid transfer, temperature changes, or vapor formation. Without a controlled release mechanism, these fluctuations could lead to serious damage or system failure. The following are a few examples of why breather valves are vital, showcasing the benefits they provide.

• Structural Damage Prevention: Rapid pressure increases or decreases can deform or rupture a tank.
• Extended Tank Life: Controlled venting processes are necessary to reduce stress on the tank walls.
• Enhanced Safety: Minimizing internal overpressure or vacuum conditions helps prevent accidents.

As one can see, breather valves provide a passive yet critical safeguard in fluid storage systems.

How Do Breather Valves Work?

Breather valves function by responding to internal pressure levels. When the tank pressure exceeds a preset threshold, the valve opens to release vapor. Conversely, when a vacuum forms, the valve allows air to enter the tank.

Key Operational Principles

• Low-Pressure Operation: Because storage tanks typically operate under low maximum allowable working pressures (MAWP), the valves must be highly sensitive.
• Weight Loading Mechanism: Most breather valves rely on weight loading, rather than spring mechanisms, to maintain precision at low set points.
• Venting Capacity: The valve ports are designed larger than the inlet nozzle to efficiently handle significant vapor flow.

Important Design Considerations

• MAWP Compatibility: The valve should be rated at least twice the desired set pressure for optimal performance.
• Avoiding Valve Chatter: Oversizing or miscalculating set pressure can lead to valve chatter and premature wear.
• Correct Sizing: Unlike high-pressure relief valves, breather valves should not be sized using overpressure percentages (e.g., 10–20%). Instead, manufacturer flow curves should always be consulted.

Ways Breather Valves Protect Storage Tanks

Breather valves offer multi-faceted protection that supports longevity and reliability in storage systems.

1. Pressure and Vacuum Control

Valves are set to operate within specific pressure ranges, typically from 0.2 psi to 5.0 psi. These settings are critical in preventing container deformation or leakage.

• Pressure settings should be below the tank’s maximum allowable pressure for optimal operation.
• Vacuum settings are necessary to prevent inward collapse due to fluid withdrawal or cooling.

2. Response to Temperature Variations

Temperature changes can cause pressure swings within sealed tanks, where for every 30°F shift, internal pressure can vary by 1.0–1.5 psi. Breather valves accommodate these changes without damaging the tank or triggering unnecessary emissions.

3. Managing Humidity and Desiccant Life

Frequent valve openings, especially in humid environments, can allow moisture to enter the tank. Over time, this can reduce the lifespan of desiccants used to absorb moisture and maintain product purity. Therefore, minimizing the frequency of openings can enhance desiccant efficiency and reduce maintenance costs.

The Practical Applications of Breather Valves

Breather valves are widely used across industries, finding common implementation within:

• Petrochemical Storage Tanks
• Pharmaceutical Processing Vessels
• Food and Beverage Manufacturing Systems
• Bulk Chemical Storage Units

Each application leverages the valve’s ability to maintain safe pressure differentials without compromising product quality or containment.

Procure Breather Valves of Need on Just NSN Parts

Understanding how breather valves function and protect storage systems is crucial for anyone involved in industrial fluid handling. Furthermore, for those who require such parts for operations, it is necessary to find a reliable source that can connect you with your various needs.

That is where Just NSN Parts comes in, the ASAP Semiconductor platform offering customers access to a wide range of high-quality pressure and vacuum relief valves that are sourced from leading manufacturers and suppliers across the globe. With a plethora of options and hands-on service, Just NSN Parts reduces the complexity of sourcing and fulfillment, ensuring that customers can meet all needs on one platform. To see how we can serve your particular needs, get in touch with one of our industry experts today!