How to calibrate flow transmitter for pitot tube
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.
*Remove connection at manifold to the process after release the process pressure
*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
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 – 5000 mmH2O
Process calibrated range: 0 – 22900 kg/h
Q =K P
0% 0 mmH2O = ( 0/5000) x 22900
= 0 kg/h
50% 2500 mmH2O = ( 2500/5000) x 22900
= 16192.7 kg/h
100% 5000 mmH2O = ( 5000/5000) x 22900
= 22900 kg/h
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