If the specific pressure sensor design of the submersible pressure transmitter or level probe is selected to measure the filling levels, this often means that the probe is used under environmental requirements which may cause failure of common level sensors.
The most unfortunate circumstances such 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 many requirements on a submersible pressure transmitter would be to have the lowest possible susceptibility to contamination or build-up of the pressure sensor by optimizing its design. Because of this , the normal design of a pressure transmitter with narrow pressure ports is not used within level probes since it would have a tendency to clog such applications.
The look of the submersible pressure transmitter and its own pressurised sensor diaphragm is optimised in order to achieve very low susceptibility to contamination. However, Vindictive in soiled media may lead to sticking of dirt particles on the stainless diaphragm. To obtain the highest accuracy and fastest response times in case of level change, the thickness of the stainless steel diaphragm is already minimised ex factory to just a few microns. Therefore, cleaning of the diaphragm should be completed with caution. Always stay away from sharp or edged tools. It is also strongly advised never 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 if 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 inner electronic measurement system and also distorts the output signal linearisation which has 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 trusted measuring instrument any more. Thus, complete replacement of the damaged instrument is absolutely necessary.
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