There is no moving part.
Most suitable for detecting sand, aggregate, lime, and so on.
It can be used for almost all substances including construction aggregates, gravels, and crushed stones, as long as they contain moisture to some extent.
The sensitivity can be set easily.
It is very easy to install and handle the meter. No deep knowledge and technique are needed.
As the current that flows measured substances is several dozen μA, heat and sparks are not produced from the electrode, which ensures the safe operation.
A measured substance that contains moisture to some extent is constantly made contact with the electrode. When the resistance between the electrode and the metal tank wall is reduced, the change of the resistance is detected and the output contact is switched. When the measured substance passes over, the output contact is restored to the initial state.