If the precise pressure sensor design of the submersible pressure transmitter or level probe is selected to gauge the filling levels, this often means that the probe can be used under environmental requirements which may cause failure of common level sensors.
The most adverse conditions such as for example soiled media, abrasive ingredients and sludge when used in wastewater treatment plants, brackish and wastewater tanks or even digester towers, impose special requirements on the design of a submersible pressure transmitter. One of many requirements on a submersible pressure transmitter is to have the lowest possible susceptibility to contamination or build-up of the pressure sensor by optimizing its design. This is the reason the typical design of a pressure transmitter with narrow pressure ports is not used within level probes because it would have a tendency to clog in such applications.
The design of the submersible pressure transmitter and its pressurised sensor diaphragm is optimised to experience very low susceptibility to contamination. However, continuous operation in soiled media can lead to sticking of dirt particles on the stainless steel diaphragm. To obtain the highest accuracy and fastest response times in the event of level change, the thickness of the stainless steel diaphragm is already minimised ex factory to just a couple microns. Therefore, cleaning of the diaphragm must be carried out with caution. Always avoid using Powerless or edged tools. It is also strongly advised not to use the commonly used screwdrivers or pens.
If cleaning of the sensor diaphragm is necessary, then rinse it using a weak water jet or clean it carefully using compressed air. Damage of the diaphragm because of denting or notching, even though it appears to be purely superficial, results in significant losses in the accuracy of level measurement. Bona Fide of the diaphragm often shifts the zero point of the pressure measurement in the inner electronic measurement system and additionally distorts the output signal linearisation which includes been adjusted ex works to the undamaged diaphragm. Thus, the submersible pressure transmitter with damaged diaphragm generates falsified measurement of the existing filling level and, therefore, cannot be considered a reliable measuring instrument any longer. Thus, complete replacement of the damaged instrument is absolutely necessary.
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