Choosing the Right Pressure Relief Valve for Your Needs: PRVs, Spunding Valves, and Breather Valves

Pressure management is a critical consideration in any food and beverage production facility. From maintaining carbonation in a fermenter to ensuring the structural safety of tanks and pipelines, pressure relief valves (PRVs), spunding valves, and breather valves play an essential role. But with so many options available, how do you select the right one for your needs?

This guide will cover the basics of pressure relief valves, spunding valves, and breather valves while exploring key considerations such as pressure ratings, connection types, and whether a tank-mounted or pipe-mounted configuration is best for your operation.

Understanding Pressure Relief Valves (PRVs)

What Are PRVs?

Pressure relief valves are devices designed to automatically release pressure from a system once it exceeds a pre-set limit. These valves are crucial for protecting equipment and ensuring operator safety.

Applications of PRVs:

• Overpressure protection in fermenters and bright beer tanks.
• Relief during CIP (clean-in-place) cycles to prevent system damage.
• Maintaining consistent pressure in pipelines and process vessels.

PRVs in breweries typically operate at lower pressures, set to 1–2 bar (15–30 psi), and are installed on fermenters and bright beer tanks to protect these vessels during fermentation and carbonation processes. It is important to note that PRVs should not be used as spunding valves, as they are much harder to calibrate and are designed primarily as safety valves to prevent tank damage. Spunding valves should always be used with a tank-mounted PRV to ensure that the tank remains protected if the spunding valve is closed.

Key Features to Consider:

• Pressure Rating: Ensure the valve matches your system's maximum allowable working pressure (MAWP).
• Materials: Stainless steel is ideal for food and beverage applications due to its durability and resistance to corrosion.
• Sanitary Design: PRVs used in breweries and distilleries should meet sanitary standards to prevent contamination.
• Adjustability: Look for PRVs that allow for fine-tuning of pressure settings to meet specific operational needs.

What Are Spunding Valves?

Spunding valves are specialized pressure relief valves that allow precise pressure control during fermentation. These valves are particularly popular in breweries where natural carbonation is desired.

Applications of Spunding Valves:

• Controlling pressure during active fermentation to achieve desired carbonation levels.
• Reducing the need for forced carbonation post-fermentation.
• Ensuring consistent product quality across batches.

Key Features to Consider:

• Pressure Range: Typically between 0.3–0.6 bar (5–9 psi) for fermentation under pressure and 0.7–0.9 bar (10–13 psi) for natural carbonation.
• Ease of Cleaning: Spunding valves with a simple, disassemblable design are easier to maintain.
• Compatibility: Ensure the valve fits the connection type on your fermenter, whether it’s a tri-clamp or threaded fitting.
• Mounting Options: Spunding valves can be mounted either to the tank head or to a blow-off arm for easier access and maintenance.

Installation and Operation:

1. Install the spunding valve on a blow-off arm using a butterfly valve to allow sealing of the vessel.
2. Fill the attached sanitizer cup halfway with a sanitizing solution (e.g., PAA).
3. Adjust the pressure based on the desired fermentation or carbonation process.

Important: Spunding valves should always be paired with a tank-mounted PRV. This ensures that if the spunding valve is accidentally closed, the tank remains protected from overpressure by the PRV.

What Are Breather Valves?

Breather valves, or vacuum relief valves, are designed to protect tanks from overpressure and vacuum conditions. These valves maintain structural integrity during filling, emptying, or temperature fluctuations. Unlike pressure relief valves, breather valves are typically used for vessels operating at atmospheric pressures.

Applications of Breather Valves:

• Protecting tanks for wine or spirits mash fermenting, brewhouse vessels, or water tanks.
• Preventing vacuum collapse during tank emptying.
• Allowing for safe venting of gases during filling or cleaning processes.

Key Features to Consider:

• Dual Action: Many breather valves offer combined pressure and vacuum relief.
• Sanitary Design: Look for models with hygienic seals and easy-to-clean surfaces.
• Flow Capacity: Choose a valve that matches your tank system's maximum gas flow rate.

Breather valves are more common on tanks designed for atmospheric pressures and are critical for preventing damage from vacuum or minimal over-pressure conditions.

What Are Pipe-Mounted PRVs?

Pipe-mounted pressure relief valves are designed specifically for piping systems, often installed as part of bypass lines for positive displacement pumps. These valves differ from tank-mounted PRVs and cannot be used interchangeably.

Applications of Pipe-Mounted PRVs:

• Protecting pipelines from overpressure conditions caused by positive displacement pumps.
• Ensuring safe operation of CIP systems by relieving excess pressure in piping.
• Safeguarding downstream equipment from damage due to pressure surges.

Key Features to Consider:

• Pressure Rating: Select a valve that aligns with the operating pressure of your pipeline.
• Flow Capacity: Ensure the valve can handle the maximum flow rate of the bypass line.
• Material Compatibility: Stainless steel construction is recommended for food and beverage environments.
• Installation Configuration: Pipe-mounted PRVs are typically installed inline and must be positioned to effectively relieve pressure without disrupting the system’s flow.

Pipe-mounted PRVs are essential for ensuring the safe operation of piping systems, particularly those involving positive displacement pumps. Always consult system specifications to determine whether a pipe-mounted or tank-mounted PRV is appropriate for your application.

Valve Comparison Table

Troubleshooting and Maintenance

Spunding Valve Maintenance Tips:

• Regularly clean the body of the spunding valve using mild soap and water under 40–50°C (105–120°F).
• Avoid exposing polycarbonate cups to high heat or strong chemicals to prevent stress fractures or discoloration.
• Periodically inspect the O-ring for signs of wear and replace as needed.

Troubleshooting Common Issues:

• Clogging: Ensure debris or krausen is directed through the blow-off tube during the initial fermentation phase to prevent valve blockage.
• Inconsistent Pressure: Verify that the pressure setpoint is calibrated properly and check for leaks in the system.

Selecting the right pressure relief valve for your operation is critical in maintaining safety, efficiency, and product quality. You can make informed decisions that protect your equipment and enhance your production processes by understanding the unique features and applications of PRVs, spunding valves, and breather valves.

For expert guidance and a wide range of sanitary valves, visit Gorman & Smith Beverage Equipment. Whether you need help choosing the right valve or designing a complete pressure management system, we’re here to help.