Pressure Equalizing Vent
This is an element with a porous membrane, fitted to a sealed housing, that lets air through while holding back liquid and dust. Its purpose is to equalise the pressure difference that forms inside the housing with temperature changes, reducing the load on the gasket and limiting the drawing in of humid air.
The air inside a closed housing expands when it heats up and contracts when it cools down. This cycle puts a repeated load on the gasket and the cover; if there is the slightest weakness in the sealing, the housing draws in humid air from outside on every cooling cycle. Over time moisture accumulates and condensation begins.
- How it works: the pores of the membrane are large enough to pass an air molecule and small enough to hold back a water droplet. This way the pressure equalises while water and dust stay outside.
- Mounting: the element is fitted on a face of the housing where water does not collect directly, preferably on the lower side; it must not be painted over and must not be covered with a label.
- Maintenance: if the membrane surface is blocked with oil, paint or mud its function ends; during periodic maintenance it is checked to be clean.
On outdoor-type receiver housings this element is the complement to the IP protection: the protection manages water ingress, the equalizing vent manages moisture build-up.
The context in which this term is used: Wireless Crane Remote Control Selection Guide