If เพรสเชอร์เกจ 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 unfortunate circumstances such as 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 many requirements on a submersible pressure transmitter would be to obtain the lowest possible susceptibility to contamination or build-up of the pressure sensor by optimizing its design. This is exactly why the normal design of a pressure transmitter with narrow pressure ports isn’t used within level probes since it would have a tendency to clog such applications.
The design 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 steel 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 carried out with caution. Always avoid using sharp or edged tools. Additionally it is strongly advised not to use the popular screwdrivers or pens.
If cleaning of the sensor diaphragm is necessary, 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. Deformation 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 includes 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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