Sunday, April 22, 2012


Calibration Procedure : Differential pressure transmitter

  • Sunday, April 22, 2012
  • denizen robo
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  • How to calibrate Differential pressure transmitter for capillary type?


    Data sheet
    Pressure calibrator (std)
    Multimeter (std)
    Hart communicator
    *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.
    *Open vent valve at drip ring and open plug at the top of the drip ring (if available) to release the process pressure
    *Clean the liquid inside the drip ring and put back the plug for high side only (if available).
    *Expose the low side to atmosphere
    *Hook up a multimeter in series with the signal to the DCS to measure current signal.
    *In this condition both capillary flange will be atm pressure at difference high
    * Multimeter should show 4mA and PV at HART communicator should shows 0 (LRV)
    *If not, do zero adjustment at transmitter using HART Communicator
    *Connect pressure calibrator to high side flange (drip ring)
    *Apply pressure depend data sheet span (URV)
    *Multimeter should show 20mA and PV at HART communicator should shows same with URV
    *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.


    Capillary flange at same elevation
    Example calculation:
    Transmitter range = 0-2 kg/cm2
    LRV = 0 kg/cm2
    URV = 2 kg/cm2.

    Related Posts:
    Control valve calibration
    Hook up drawing

    2 Responses to “Calibration Procedure : Differential pressure transmitter”

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