How to calibrate control valve?
1) Data sheet
2) Hart Communicator
Step wise Procedure:
*Ask panel man to put the controller in manual mode for control loop
*Isolate the Control valve from the process.
WARNING – The Isolation of control valve from the process shall be done by field operator. Careful step shall be done to ensure no upset to the operation.
*Hook up HART Communicator and verify some parameters by refer to data sheet such as Tag Number, OP and etc.
*Change from normal mode to setup mode
*Select auto find stop (wait some minute)
*If full open is more than 100% select open adjustment and put new number as per calculation
*Make an auto calibration ( wait some minute)
*Verify the linearity by increasing and decreasing the travel (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
*Fill the calibration form and file it for future reference.
A: Max travel from stem 70mm
B: Scale plate 50mm
New open adjustment should be (50/70) X 100 = 71.48%