In packaging of missiles, engines and delicate electronic instruments it is essential to protect the equipment from the effects of moisture. For this purpose, shipping and/ or storage containers must be hermetically sealed and dry. However, these containers may be exposed to variations in pressure and vacuum of the order of 5.7 psid (pounds per square inch differential) due to temperature and/or altitude variations. In order to cope with pressures of this magnitude, the container should be made of extremely resistant materials, which would make it cumbersome,  too heavy and expensive during storage and shipping.

The problem can be solved through the adoption of a “controlled venting” system, or vent valves. These low-pressure and high-flow valves automatically regulate the pressure inside the container according to changes in ambient pressure, preventing formation of excessive differential pressures during air transport, as well as rail or truck transport at high altitudes.