In this session we are gonna discuss about calibration of Dp level transmitter in the field
Procedures to calibrate Level transmitter in field
- Ask panel man to put the controller in manual mode for control loop and to put it on MOS(maintenance override switch) 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.
- Release both pressure and drain low and high side liquid throughout manifold drain.
- Open both plug at seal pot
- Top up seal liquid for low side until half of seal pot.
- Remove tubing at high side of manifold
- Hook up pressure calibrator at high side and isolate the vent valve
- Hook up a multimeter in series with the signal to the DCS to measure current signal.
- Apply pressure as per calculation when level equivalent to zero
- Multimeter should show 4mA
- If not, do zero adjustment at transmitter using HART Communicator
- Apply pressure as per calculation when level equivalent to 100 % Multimeter should show 20mA
- If not, do span adjustment at transmitter using HART Communicator
- 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.
- Note: There is many way to perform calibration for DP level but the important thing is the DP reading at HART communicator should same with the LRV and URV