If the specific 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 would cause failure of common level sensors.
Certain as soiled media, abrasive ingredients and sludge when used in wastewater treatment plants, brackish and wastewater tanks as well as digester towers, impose special requirements on the design of a submersible pressure transmitter. One of the main requirements on a submersible pressure transmitter is to obtain the lowest possible susceptibility to contamination or build-up of the pressure sensor by optimizing its design. This is exactly why 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 look of the submersible pressure transmitter and its pressurised sensor diaphragm is optimised in order to achieve very low susceptibility to contamination. However, continuous operation in soiled media may lead to sticking of dirt particles on the stainless diaphragm. To get the highest accuracy and fastest response times in case of level change, the thickness of this stainless steel diaphragm is already minimised ex factory to just a couple microns. Therefore, cleaning of the diaphragm should be carried out with caution. Always stay away from sharp 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 utilizing a weak water jet or clean it carefully using compressed air. Damage of the diaphragm due to denting or notching, even though it seems to be purely superficial, leads to significant losses in the accuracy of level measurement. Deformation of the diaphragm often shifts the zero point of the pressure measurement in the internal 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, cannot be considered a trusted measuring instrument any longer. Thus, complete replacement of the damaged instrument is completely necessary.
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