This is a very real packaging concern because the drop in atmospheric pressure induces pressure differences between the package and the shipper, resulting in shipping damage to the product.
The issue of altitude usually manifests itself by affecting package integrity. The ASTM 6653 test procedure, the standard test used to determine how the effects of higher altitude will affect package integrity, should be implemented on all packages.
Common applications include simulating package failures during transport of foods in high altitude, its effects on design of electronic devices since air is used as an electric insulating medium, aerospace industry testing to ensure their products can endure pressure changes with space travel, and the cosmetic industry’s need for testing due to different levels of intense sensitivity in consumers.
Although your application may not require vacuum levels to 29.9"Hg, Terra builds its chambers to support this vacuum level due to safety concerns.
Variations in operators and operating protocol may lead to inadvertent spikes in vacuum pressure. Because these chambers are small, a few moments of vacuum operation beyond your target vacuum can subject them to substantially higher stress than you intend. Even a safety release switch is no guarantee that a chamber won't experience high vacuum pressure since these valves are not tamper-proof.
The best way to guarantee the safety of your parts and personnel is to use a chamber designed to sustain high vacuum levels. That's why Terra fabricates these chambers of 1" thick acrylic.
Chambers lose vacuum pressure initially due to air released from acrylic walls during first three hours. If vacuum level of 29.9"Hg is restored following this initial drop in vacuum pressure, chambers hold 29.9"Hg with no detectable change in pressure over duration of test.