Electromagnetic flowmeter shows readings without water flow
Thread Content
The DN15 electromagnetic flowmeter at the customer’s site is in a closed valve state, yet it keeps displaying the instantaneous flow rate. Electromagnetic interference has been ruled out at the site, as has the possibility of the valve being completely closed. What could be the cause of this? What faults need to be addressed?
I have encountered a similar situation before; upon inspection, it was found that a capacitor inside the flow meter was damaged, which caused abnormal signals； Another time, it was because of a loose connection in the transmission line, which caused unstable signals and led to an indication of data traffic. You can take a look as reference
Then the person upstairs said that if it’s a fluctuating flow rate, check the grounding wires; also check the air traffic control alarms. If that doesn’t work, see if small-flow cutoff is not set – if the flow rate is low, it should be cut off
First, is there water in the pipe with the valve closed? If there is water, is the pipe full? In case 1, when there is no water, there should be an alarm indicating an empty pipe; in case 2, when there is water, how severe is the vibration of the pipe? Additionally, the electrodes can be removed for cleaning and then zero calibration can be performed again.
It could be that the zero point of the flow meter is unstable or there is damage inside the sensor. It is recommended to check and recalibrate the zero point of the flow meter; if the problem persists, the flow meter may need to be repaired or its sensor replaced. .
Grounding, interference. It is also possible to check whether there are any issues with the electrodes and excitation coils; if the value is low, simply cut them off