Hi,

We have recently replaced an Electro-magnetic flowmeter with a New Model (FEP 300) from ABB. Subsequent to the installation we are finding the flow to be fluctuating continuously by over 5% of full-scale range. Earthing has been checked & it seems there are no issues with earthing.

Does anybody have any other idea of what can be checked?

Regards,
Niraj

 

There are several possibilities. The most likely is that the flow really is fluctuating. The new meter may be seeing it, where the old meter didn¹t. You could have entrained air in the meter. You could still have a bad ground issue.

Where are you reading the fluctuation? At the meter? Which output are you looking at?

Good luck,
Walt

Walt Boyes, Life Fellow, ISA; Fellow InstMC
Chartered Measurement and Control Technologist
Spitzer and Boyes LLC
www.spitzerandboyes.com

**Spitzer and Boyes LLC publishes the Industrial Automation and Process Control INSIDER (www.iainsider.com)**

 

Another possibility is that the location of the meter where it is installed in the flow line. Typically, a magnetic flow meter requires that the inflow of the fluid is in a straight pipe that is 10x its diameter. The outflow has to be a straight pipe of 5 x the meter diameter. This is to avoid turbulent flow causing the sensors to pick up as noise.

The electrical signal from the flow sensor is very small. Make sure to use good shielded cable. Ground the shield properly to remove any noise.

The transmitter may have setting to dampen the flow signal. It may have to be tuned to work properly.

 

Hi there

I have exactly the same issue with the same flow meter. Did you solve it?

If I pull it out and bench test it all is fine. put it back the reading is erratic and it won't auto zero. Pipe is full and no flow.
If you can help It would be great.

Thanks

 

In all likelihood, you have a grounding problem. Call your vendor for service.

Walt

Walt Boyes, Life Fellow, ISA; Fellow InstMC
Chartered Measurement and Control Technologist
Spitzer and Boyes LLC
www.spitzerandboyes.com

**Spitzer and Boyes LLC publishes the Industrial Automation and Process Control INSIDER (www.iainsider.com)**