mass flow meter drifting from actual reading

[teoaj]

Have you all met this problem of a coriolis mass flow meter shows that there is a flow of 300 liters per hour while there actually has no flow in the flow meter. Futhermore, the reading keeps increasing over the time and the trend of the flow increment is pretty steady.What reasons could possibly contribute to this? Is it because of external vibration? or air bubble inside the flow meter? Thanks.

 

[GregLocock]

Well, is it a flow meter with a max scale of 100000000 litre per hour, or 1?



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[teoaj]

Hi,

The scale is 0 ~ 16000 liter per hour, with an accuracy of plus minus 0.15%.

Or is this a transmitter problem?

Thanks.

teoaj.

 

[btrueblood]

Sounds like a bunged-up meter to me. Do you have a process fluid that can cake onto the walls of the meter, or corrode them?

 

[teoaj]

Thanks btrueblood.
My process fluid is just a normal solvent, ethanol.
However, after we repack the line, the meter became to be ok.

 

[BonnKK]

Talking about this. My site do have this problem. Its like after issuing the product to a truck. All the valves are shut. But from the control room, it shows that there is flow in the meter. Its really weird. The worst thing is that the meter can go reverse without any flow.

Not sure if it is valve passing or is due to the coriolis meter.

 

[btrueblood]

Oh. Or is it residual ethanol boiling in the line, and bubbles causing flow/reversed flow?

 

[joselitosouza]

I already had the same problem. In my case was:
We had several lines (tubing) supplied by only one general(mother) line (tube), and each (daugther) line was connected to the mother by TEEs. So, when we were measuring in one line, the liquid was coming up from the mother and, each daugther line which were not measuring in the same time had the liquid movement reverse by "venture force" (decreasing the pressure) , and after the stop off all, the liquid move positive again (reincreasing the pressure), with no end line valvs opened.
The solution were separate the lines or exchange the TEEs for small vessels.
Hope could be clear.

 

[KiwiMace]

Check the meter mode - Is it in 'integration' or 'measure'