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 can be used under environmental requirements which may cause failure of common level sensors.
Uncaring as soiled media, abrasive ingredients and sludge when found in wastewater treatment plants, brackish and wastewater tanks as well as digester towers, impose special requirements on the look 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. This is why the typical design of a pressure transmitter with narrow pressure ports isn’t used within level probes since it would tend to clog such applications.
The design 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 obtain the highest accuracy and fastest response times in the event 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 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, 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 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, can’t be considered a trusted measuring instrument any longer. Thus, complete replacement of the damaged instrument is absolutely necessary.
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