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Shift in Baseline DP reading 3051SFC(MVT)

Hi,

We are operating a 3051SFC (MVT) Compact Conditioning Orifice Flow meter on a gas line.

 

Recently we dropped some pressure in the line and the baseline DP to negative.

At the time there was no other scheduled or work undertaken on this pipe. It is not connected to any other process. The manifold has been checked twice. Back pressure is held via a Fisher EZR.

This creates a potential conflict over reliability of the readings as we used a DP cutoff of 0.025 previously and so we are not recording similar flow periods.

Process Conditions: Upstream: 500-1000kPa / Downstream: Atmospheric / Fluid Type: Natural Gas

Any thoughts on this is greatly appreciated.

Cheers

Kitndavj

• DP Flow

kitndavj

• 3 Apr 2015 5:37 PM
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1 Reply

• Brian Fretschel

  

  • 3 Apr 2015 7:54 PM

  Hi Kitndavj,
  
  It’s very interesting that a decrease in static pressure is causing you to see a negative differential pressure. You said that the process stayed the exact same right? Sometimes there can be an effect on the DP when there is a large decrease in static pressure but generally not enough to cause something like this.
  
  If you would like to run through a quick verification procedure and send over to me – we can further discuss offline. Please close the low side valve, open the equalize valve, and keep the high side valve open. It would be good to see your data while the valves are in this configuration. This should give us visibility into if you have a good zero on the transmitter or not.
  
  Brian F.
  Brian.Fretschel@Emerson.com

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