How to calibrate flow transmitter for Capillary type

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