If the precise pressure sensor design of the submersible pressure transmitter or level probe is selected to measure the filling levels, this can indicate that the probe is used under environmental requirements which may cause failure of common level sensors.
Victim as for example soiled media, abrasive ingredients and sludge when found 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 would be to obtain the lowest possible susceptibility to contamination or build-up of the pressure sensor by optimizing its design. That is why the typical design of a pressure transmitter with narrow pressure ports isn’t used within level probes because it would have a tendency to clog in such applications.
The design of the submersible pressure transmitter and its own 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 diaphragm. To get 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 stay away from sharp or edged tools. Additionally it is strongly advised not to use the commonly used screwdrivers or pens.
If cleaning of the sensor diaphragm is essential, then rinse it utilizing a weak water jet or clean it carefully using compressed air. Damage of the diaphragm due to denting or notching, even though it appears to be purely superficial, results in significant losses in the accuracy of level measurement. Deformation 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 current filling level and, therefore, can’t be considered a reliable measuring instrument any longer. Thus, complete replacement of the damaged instrument is completely necessary.
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