Procedure of capacitance type level Transmitter calibration:
Remove the level transmitter from the system (tank).
Check whether the transmitter shows zero reading by connecting with multimeter otherwise release the pressure.
For a smart transmitter:
Connect 475 hart communicator and multimeter to the transmitter.
Put Multimeter to ma.
Fill in the correct density of the corresponding liquid and record the readings. Fill fluid in ascending and descending orders at 25%, 50%, 75% and 100% and write down the measurements.
Check for errors if there is zero and span adjusts should be done.
For zero calibration:
- Drain the liquid and check the multimeter if not 0, then go to the HART sensor trim option and go to zero trim and the HART communicator automatically trim the sensor to zero.
For span calibration:
Fill 100 percent and wait a while for the sensor to be trimmed and pick the length cut in the HART communicator.
After completing zero and span trimming, check the reading again at 0%, 25%, 50%, 75% and 100%.
In case of non smart capacitance type transmitter:
Connect a multimeter and rotate the zero pot and stop when multimeter shows 4ma. Fill the chamber to maximum liquid level and rotate the span screw to 20ma.
Repeat these steps and check all readings