Cleaning of submersible pressure transmitters or level probes

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 is used under environmental requirements which would cause failure of common level sensors.
The most unfortunate circumstances such as 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 the main 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. That is why the normal design of a pressure transmitter with narrow pressure ports isn’t used within level probes since it would tend 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 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 few microns. Therefore, cleaning of the diaphragm must be carried out with caution. Always stay away from sharp or edged tools. It is also strongly advised not to use the popular 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 because of 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 internal electronic measurement system and additionally distorts the output signal linearisation which has been adjusted ex works to the undamaged diaphragm. Thus, Collapse with damaged diaphragm generates falsified measurement of the existing filling level and, therefore, can’t be considered a reliable measuring instrument any more. Thus, complete replacement of the damaged instrument is completely necessary.
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