Why do electromagnetic flowmeters exhibit large fluctuations when there is no flow?
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An electromagnetic flowmeter with water as the medium does not show a reading of zero when there is no flow, and its readings fluctuate greatly. What are the reasons that cause its fluctuations? Moreover, the fluctuations are highly irregular and occur very rapidly; they can reach 25% of the range, and sometimes even go negative. I don’t know what caused it. This flow meter worked well before the machine stopped. The pipe diameter should be 150, and it’s plug-in type. It’s not tubular. Split-type. That’s all! The process data indicates that the flow rate was zero after shutdown, but fluctuations appeared suddenly after some time had passed. Anyway, regardless of when the fluctuations start, what are the reasons that can cause such irregular fluctuations in an electromagnetic flowmeter? The readings can fluctuate from 0 to 25% of the full scale, and then drop back down, oscillating back and forth. Today, the fluctuations seem even greater. There is no pattern; it cannot be described.
After stopping, there is a pipeline cleaning or backflow flushing!
Check if there are any interfering factors in the vicinity, such as motors or frequency converters
Check if there is a problem with the wiring; if not, it’s likely broken.
Check the grounding ring; it’s possible that the connection is loose.
1. Check the grounding of the electromagnetic flowmeter; examine both the grounding of the flowmeter and the shielding of the signal cable. 2. Check the air traffic control alarm settings. 3. Are there any devices that cause significant interference, such as welders, turning on or off near the area where fluctuations occur?
1. Is the flow meter grounded? 2. Is the pipe too thick? Is there an empty tube phenomenon in the flow meter? 3. Are there any strong interference sources near the flow meter accessories?
1. Check the meter grounding. 2. Are there any strong interference sources near the flow meter accessories?
It should mainly be a problem with the instrument grounding. Check it carefully. Is there any strong electrical interference on the other line?
Contact the manufacturer of the electromagnetic flowmeter to ask if there is a function called “zeroing with an empty pipe”; enabling that function should solve the issue.