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 may cause failure of common level sensors.
The most adverse conditions such as for example 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 look 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. This is exactly why the typical design of a pressure transmitter with narrow pressure ports is not 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 suprisingly 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 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 not 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 appears to be purely superficial, results in significant losses in the accuracy of level measurement. Fierce 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 reliable measuring instrument any more. Thus, complete replacement of the damaged instrument is absolutely necessary.
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