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.
Brazen 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 design of a submersible pressure transmitter. One of many 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. Because of this , the typical design of a pressure transmitter with narrow pressure ports isn’t used within level probes because it would tend to clog such applications.
Shocking 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 obtain the highest accuracy and fastest response times in case of level change, the thickness of the stainless steel diaphragm has already been minimised ex factory to just a couple microns. Therefore, cleaning of the diaphragm must 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 essential, 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 appears to be purely superficial, leads to 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, 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 completely necessary.
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