The Basics of Vacuum Relief In a Brewery

Introduction

Your fermenters and brite tanks are constantly undergoing pressure changes. Routine activities such as brewing, fermenting, cleaning in place, and moving products can potentially implode a poorly vented tank. Understanding how and why vacuum failure happens is important so you can keep your tanks in service.

What is Vacuum Pressure?

Vacuum pressure occurs if your tank is poorly vented or the relief valve malfunctions. The pressure within your fermenter or brite tank will drop, causing a differential between your tank's internal and atmospheric pressure. When that pressure differential exceeds the tank's external pressure rating, the vessel will experience catastrophic failure. The end result is almost always a complete loss and high replacement costs.

How Does Vacuum Failure Happen?

The threat of vacuum failure inside a brewery is very real. Many of the day-to-day jobs in your operation create conditions that can directly lead to vacuum failure. Those activities include:

Pumping or Draining an Unvented Tank

As you pump or drain a tank, you remove beer but do not allow air to enter. As your tank continues to empty, the small amount of CO2 or air in the tank has to fill up the void created by the emptied beer. This creates a low-pressure environment in the tank, and the weight of the atmosphere will implode the tank.

Overfilling a Tank

If you overfill a fermenter or a brite tank to the point where beer fills the vent line, you can create a siphon. Like pumping or draining an unvented tank, beer will siphon out without allowing air to enter the tank. Once enough beer has siphoned out the vent line, your tank will crumble under the weight of the atmosphere.

Hot CIP Followed by Cold Rinse

After you clean a fermenter or brite tank, the air inside is very hot. If your rinse water temperature is too cold, it could cause a very rapid drop in pressure within the tank because cold air is much more dense than hot air. When you crash the air temperature inside an unvented tank, the tank can implode instantly!

Using Caustic Soda After Fermentation

It is common practice to clean a fermenter once you have moved the beer to a brite tank. A byproduct of fermentation is CO2. If you introduce caustic soda to a fermenter full of CO2, a chemical reaction will occur, converting the gas CO2 into a solid. This will lower the pressure inside of your fermenter, and if it isn't vented properly, it can lead to vacuum failure.

The Importance of a Vacuum Relief Valve

A vacuum relief valve protects your tanks from vacuum failure by allowing air into them when the inside pressure starts to drop. Your fermenters and brite tanks are an important investment for your brewery. Not only are they costly, but they enable you to create the beer your customers love to drink. Installing a properly sized vacuum relief valve is the best way to keep your tanks in service.

Buying the right-sized vacuum relief valve is an important step. Vacuum relief valves are not one-size-fits-all. Because tanks are all engineered differently and no two breweries use the exact same cleaning regimen, the valve manufacturer usually sizes the valves for your unique application. 

Different Types of Vaccum Relief Valves

• Weight Loaded Relief Valve
• Spring Loaded Relief Valve
• Pressure/Vacuum Relief Valve

Vacuum relief valves come in a variety of shapes and sizes. Depending on the application, they can use spring-loaded resistance or a weight-loaded resistance. Some manufacturers offer a valve that can protect from both vacuum and pressure. These pressure/vacuum relief valves (PVRV) keep your tank from imploding and exploding outward from too much internal pressure.

Vacuum Relief Valve Inspections

Your vacuum relief valves are useless if they are not working correctly. It is important to inspect your valves regularly. During the initial usage phase, you should inspect your valves more frequently than you think is necessary. The idea is to discover a potential problem before it becomes a real problem.

When inspecting your valve, ensure it is being cleaned properly during clean-in-place and that it can still mechanically function properly.