Sunday, July 15, 2012


How to calibrate offset Displacer level transmitter

  • Sunday, July 15, 2012
  • denizen robo
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  • How to calibrate offset Displacer  level transmitter



    *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)

    Example calculation:
    Low S.G=0.802
    High S.G= 0.992
    A= 810mm (measurement length)
    B= 410mm (off set)
    C=A+B=1220mm (Displacer length)
    0%    = (High S.G x off set length) + (low S.G x A)
        = (0.992 x 410) + (0.802 x 810)
        = 406.72 + 649.62
        = 1056.34mm
    100%     = (High S.G x C)
        = (0.992 x 1220)
        = 1210.24mm
    Related post:
    Calibration displacer type level transmitter
    Calibration flow transmitter - DP type
    Calibration Differential pressure transmitter

    2 Responses to “How to calibrate offset Displacer level transmitter”

    Sri Aanand said...
    September 26, 2014 at 12:06 AM This comment has been removed by a blog administrator.

    Dan6y said...
    November 18, 2015 at 5:18 AM

    What is S.G?
    Is it nominal S.G statutes?

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