Tuesday, April 24, 2012

2

Calibration Procedure : Differential Pressure Flow Transmitter

  • Tuesday, April 24, 2012
  • denizen robo
  • Share

  • 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

    2 Responses to “Calibration Procedure : Differential Pressure Flow Transmitter”

    john wood said...
    October 25, 2013 at 11:00 AM

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


    manzi said...
    January 25, 2014 at 9:31 PM

    ( 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.!


    Post a Comment

    Subscribe