Hi everyone! I have a problem with Yokogawa AXFA14C. We have unstable zero. We completely filled the pipe and did zero executing. But it didn’t help. It’s electromagnetic type. Reading not correct. We think maybe inside the pipe magnets is dirty. But Adhessive is 0 M ohm. Our Flow Span 0-500 m3/h. Nominal Size the tube is 200mm. Motor is working about 183.6 m3/h (50 HZ), but our readings is 9.8 m3/h maximum. We checked all parameters. And we can’t do correct zero. Maybe the pipe is dirty?

 

Check your earthing. Ensure flow tube etc. is earthed as per requirements, with or without earth rings.
also check pipe earthing is correct.
check for impressed voltages on your earth to the flow tube.
physical inspection of flow tube internals, look for tube coating, electrode coating, electrode erosion, process leak of fluid into flow tube case.

 

OK. We have PE and IE together, but screen isolated on Transmitter.
Second thing it’s grounding rings. We don’t have grounding rings on Flow Element. You mean check grounding on the pipes?

 

impressed or stray voltages that appear on piping also appear by contact in the process fluid which can impact the measured signal detected by the mag tube electrode. it is important that the mag tube electrode is not the path to earth for other electrical currents.