Calibration of Dp level transmitter at field

Introduction

In this session we are gonna discuss about calibration of Dp level transmitter  in the field

Material Required

• Data sheet
• Pressure calibrator (std)
• Multimeter (std)
• Hart communicator

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