What does a level measuring system comprise?
Let us first consider an invasive level measuring system. It comprises a level sensing probe that can either be mounted from the top or side of the vessel. When the probe comes in contact with the material in the vessel the physical event is converted to an electrical signal either directly or by an electronic insert in the probe head. The signal after primary processing is transmitted to the evaluation unit which converts it to a suitable output, either, as a change in the state of a relay contact or an analogue 4 to 20 mA output for Alarm annunciation / control / recording. For limit switching applications the probe can be either mounted from top or side of the vessel. For continuous level monitoring however, the probe is always mounted from the top. In the case of non-invasive level measuring system the probe is normally mounted from the top of the vessel. In certain applications it can also be mounted from the side. The probe does not come in contact with the material directly but
