How to calibrate flow transmitter for Capillary type
Material
Data sheet
Pressure calibrator (std)
Multimeter (std)
Hart communicator
Step
*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..
*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).
*Connect pressure calibrator to high side of manifold
*Expose the low side to atmosphere
*Hook up a multimeter in series with the signal to the DCS to measure current signal.
*Apply pressure as per data sheet LRV (normally 0mmH2O)
Multimeter should show 4mA
If not, do zero adjustment at transmitter using HART Communicator
*Apply pressure as per data sheet URV
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
*Fill the calibration form and file it for future reference.
Example calculation
Instrument calibrated range: 0 – 2500 mmH2O
Process calibrated range: 0 – 130 m3/h
Q =K P
0% 0 mmH2O = ( 0/2500) x 130
= 0 m3/h
50% 1250 mmH2O = ( 1250/2500) x 130
= 91.9 m3/h
100% 2500 mmH2O = ( 2500/2500) x 130
= 130 m3/h
