Sunday, July 8, 2012


How to calibrate Displacer level transmitter

  • Sunday, July 8, 2012
  • denizen robo
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  • Calibration procedure - Displacer type level transmitter



    *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.
    Remove isolation drain valve and open the vent flange
    *Connect water pump to drain line and line up the reference tube
    *Calculate the new measurement to get equivalent up trust force with S.G and length
    *Mark on the chamber for reference calibration
    *Hook up a multimeter in series with the signal to the DCS to measure current signal.
    *Apply water level until 0% marking on chamber
    *Multimeter should show 4mA
    If not, do zero adjustment at transmitter using HART Communicator
    Apply water level until 100% marking on chamber
    *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

    Example Calculation:
    Low S.G=0.802
    High S.G= 0.992
    A= 810mm (measurement length)
    0%    = (A x Low S.G)
        = (810 x 0.802)
        = 649.42 mm
    100%     = (A x High S.G)
        = (810 x 0.992)
        = 803.52 mm

    Related posts:
    DP type level transmiiter
    DP type level - Capillary
    Bubbler type level transmitter

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