If the precise pressure sensor design of the submersible pressure transmitter or level probe is selected to measure the filling levels, this often means that the probe can be used under environmental requirements which would cause failure of common level sensors.
The most adverse conditions such as for example soiled media, abrasive ingredients and sludge when found in wastewater treatment plants, brackish and wastewater tanks and even digester towers, impose special requirements on the look of a submersible pressure transmitter. One of the main 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 isn’t used within level probes because it would tend to clog in such applications.
The look 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 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 this stainless steel diaphragm has already been minimised ex factory to just a couple microns. Therefore, cleaning of the diaphragm should be completed with caution. Always stay away from sharp or edged tools. Additionally it is strongly advised never to use the popular screwdrivers or pens.
If cleaning of the sensor diaphragm is essential, then rinse it using 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. Verify 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 has 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 reliable measuring instrument any longer. Thus, complete replacement of the damaged instrument is absolutely necessary.
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