Calibration Procedure : Differential Pressure Flow Transmitter


How to calibrate flow DP transmitter 

Material
Data sheet
Pressure calibrator (std)
Multimeter (std)
Hart communicator

Step
*Ask panel man to put the controller in manual mode for control loop and to put it on MOS for ESD loop.
*Hook up HART Communicator and verify some parameters by refer to data sheet. Typical parameters are, tag number, PV, LRV and URV.
*Isolate the instrument from the process.
WARNING – If the process is hazardous, please unsure proper flushing is done to remove the entire hazard.
*Release both pressure and drain low and high side liquid throughout manifold drain.
*Connect pressure calibrator to high side of manifold
*Expose the low side to atmosphere
*Hook up a multimeter in series with the signal to the DCS to measure current signal.
*Apply pressure as per data sheet LRV (normally 0mmH2O)
*Multimeter should show 4mA
*If not, do zero adjustment at transmitter using HART Communicator
*Apply pressure as per data sheet URV
*Multimeter should show 20mA
*If not, do span adjustment at transmitter using HART Communicator
*Verify the linearity by increasing and decreasing the pressure (0%,25%,50%,75%,100%,75%,50%,25% and 0%of range)
*After completion of the job ask panel operator to put loops back in normal mode or normalize the MOS
Fill the calibration form and file it for future reference.


calibration_differential_pressure_flow_transmitter
Example calculation

Instrument calibrated range: 0 – 2500 mmH2O
Process calibrated range: 0 – 105000 Nm3/h
Q =K  P
0%  0 mmH2O = ( 0/2500) x 105000
= 0 Nm3/h 
50%  1250 mmH2O = ( 1250/2500) x 105000
= 7424.6 Nm3/h 
100%  2500 mmH2O = ( 2500/2500) x 105000
= 105000 Nm3/h
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3 comments:

  1. Indeed very informative.
    I like the topic flow transmitters.
    Dwyer flow transmitters are high efficiency transmitters.

    ReplyDelete
  2. ( 1250/2500) x 105000
    = 7424.6 Nm3/h
    Is there some calculation error ? i got the result as 52500, plz correct me if am wrong.!

    ReplyDelete
  3. ( 1250/2500) x 105000
    = 7424.6 Nm3/h
    Is there some calculation error ? i got the result as 52500Nm3/h

    ReplyDelete