Pressure differentials in a hermetically sealed enclosure are a result of the heat generated by electrical and electronic components in the enclosure, as well as the fluctuation of the outside temperature. In the case of negative pressure or vacuum, for example, dust and humidity can be absorbed through the door seal and can enter the enclosure.

The 880 PCD1 Pressure Compensation Device provides a protected enclosure environment for valuable and crucial components with a 4X rated degree of protection. A semipermeable membrane inside the device allows air and humidity to leave the enclosure. In the opposite direction, it only allows dry air into the enclosure while not allowing humidity and dust from the outside to enter.