The Function of Purge Valves in Custom Cargo Cases

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Design custom cargo cases with purge valves to equalize pressure during atmospheric changes.

At Packaging Strategies, Inc., we design custom transit cases for numerous industries. These cases are designed to suit the user’s specific needs and include various design features that provide specific levels of protection and support. We can ensure a waterproof construction and pressure equalization by adding purge valves when designing waterproof cases for extreme or unpredictable environments. Any waterproof case should have one of these valves. What is the function of purge valves in custom cases? Let Packaging Strategies, Inc. help you understand the importance of this innovative case design element. 

Purge Valves Keep Out Water While Encouraging Air Flow

A purge valve is designed to let air flow freely in and out of the case while simultaneously keeping water and dust out. This makes your case watertight but not airtight. Airflow is essential for watertight cases, so the atmospheric pressure changes due to altitude fluctuations do not create an imbalance in the pressure inside and outside the case. If custom cargo cases travel from sea level to high above sea level without a purge valve, the change in pressure can lead to a damaged or disfigured case – and ruined equipment inside of it. 

The Two Types of Purge Valves

Automatic Purge Valves

There are two types of purge valves, the first being automatic valves. The function of these purge valves is to regulate airflow and change pressure automatically. High-quality custom cargo cases feature automatic valves, so the user does not have to worry about managing the valve or air flow themselves. 

Manual Purge Valves

Lesser brands and lower quality cases will use manual purge valves, which require the user to press a button that releases pressure. This is not the best option since a case might already be damaged when a person is able adjust the purge valve. If you want to ensure that your equipment reaches its destination unharmed and your case remains durable and undamaged, it’s best to invest in high-quality automatic purge valves. 

How Purge Valves Function 

First, a purge valve prevents a vacuum from being created within a closed case. Imagine a pickle jar that is impossible to open, and when it does, a “pop” is heard as the lid finally releases from the jar. If a vacuum is created within your case, it may be near impossible to open and may be damaged once it is. 

How does the purge valve keep water out? You may wonder if a purge valve can let air in and out, how can it remain watertight? The detailed answer involves some knowledge of chemistry and how specific molecules are “hydrophobic” or repel water. Consider how olive oil never mixes with water when placed in the same container. 

Purge valves are often designed with holes covered by an incredibly thin membrane made with hydrophobic materials. The membrane lets air pass through, but because it is hydrophobic, water does not pass into the case. Contact Packaging Strategies, Inc. for more information on how purge valves can be used to protect your equipment. 


Packaging Strategies has assembled a team with over 100 years of experience in design, engineering, development, manufacturing, and sales. We created the Packaging Strategies Design and Technology Center to create and manufacture complete systems integration packages and container solutions of all sizes and materials for our clientele. Many of these clients are federal agencies or in the private sector. No matter what you need to carry, Packaging Strategies is sure to have the right case for the job. You can view our website here, and follow us on Facebook, Twitter, Flickr, and LinkedIn.

This entry was posted on Wednesday, May 8th, 2024 at 9:21 am. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.