Calibration Procedure : Differential pressure transmitter

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.

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