The Rosemount 8705-8732 electromagnetic flowmeter returns to zero once powered on; it resets to zero again within less than half an hour after each power cycle
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The medium level in the pipe was full; it was slightly low before the problem occurred, but the trend was normal. It is well grounded, and there are no interference sources in the vicinity. Could there be any other possible problems?
There is oxidation in the wiring of the sensors and converters
It is an integrated flow meter; I’m not sure if the gauge allows one to see the wires of the sensor. Have you encountered a similar situation?
Does the original poster have a curve graph? Whether it drops to zero suddenly or gradually; I hope a more detailed description of the operating conditions can be provided
It would be best to remove it in order to check the electrodes and lining; it’s likely that the electrodes have been corroded through, allowing the medium to enter the excitation coil and cause further corrosion……
What operating conditions? If there are magnetic powder substances in the medium, this phenomenon may occur.
Agree with the view from the second floor; if distractions and other factors are ruled out, it’s still necessary to check the electrodes and lining to see if they are functioning properly
To provide feedback on the processing results, we contacted the manufacturer and had several parameters adjusted; measurements of the coil resistance and other values showed no issues. Finally, when we disassembled the sensor, we found that a layer of crust had formed on the inner wall due to the catalyst. . . It’s about 1-2 mm thick; it peels off in pieces when tapped with a tool, and the electrodes are covered by it. . . This flow meter is used in flue gas desulfurization and denitration systems, with slurry as the medium; under normal operating conditions, there should not be such a large amount of catalyst present. It was disassembled once before and was quite clean, so it wasn’t disassembled at first. I still don’t understand why there is flow as soon as power is applied; the trend is one of a rapid return to zero, over about ten to twenty seconds, with a gradual decrease in flow.