Pressure-resistant inductive proximity switches are used for a multitude of applications, especially in the field of hydraulics, as well as for various pressures (up to 500 bar). Pressure-resistance requires thick housing walls, particularly also at the sensing face. The main problem lays in providing an acceptable operating distance, despite the thick walls.

The required pressure-resistance (up to 500 bar, and over) of Contrinex high-pressure-resistant proximity switches is obtained exclusively in the "direct way", i.e. by means of sufficient wall strength. At the sensing face, a ceramic disk of sufficient thickness to withstand pressure without further reinforcement measures inside the housing is used. Thus, no auxiliary constructions, such as for instance internal supports, are required. The entire electronic module, including the ferrite core and the coil, are placed in the pressure-free core of the housing. However, due to the thickness of the ceramic disk of 2.5 mm (P20), using a proximity switch module with a normal operating distance (in this case, 2 mm) would result in a usable operating distance of less than zero. The solution to this problem is described below.