Magnet-operated immersion probes are used in clean liquids, such as solvents or oils. The float, guided by a probe tube, floats on the liquid surface. By means of its magnetic field, the ring magnet built into the float activates the reed contacts installed in the guide pipe. These are switched when the float is located in the appropriate position.
The reed contacts are designed as normally closed, normally open or change-over contact switches. The measurement is independent of the electrical properties of the liquid, pressure, temperature and density.