Differential pressure transmitter calibration steps:
1. Open the bypass valve on the manifold.
2. Close the block valve on the legs (impulse piping) on the high side and the low side.
3. Disconnect the impulse piping transmitter.
4 Connect the handpump output to the transmitter input high side according to specifications and leave the low side open at atmospheric pressure.
5. Connect the multimeter in series with the transmitter output.
6. Provide input pressure of 0%, 25%, 50%, 75%, 100% according to the working range of the transmitter.
7. Record the results on the test form as As Found UP data.
8. Provide input pressure of 100%, 75%, 50%, 25%, 0% according to the working range of the transmitter.
9 Record the results on the test form as As Found DOWN data.
Error = (actual indication – standard) / range X 100%.
10. If necessary make adjustments.
Adjustment
For adjustments, you can use the Hart Communicator if the transmitter supports HART, it can also be adjusted manually via the button on the transmitter.
1. Provide a minimum pressure input (0%) according to the working range of the transmitter.
2. Measure the transmitter output current.
3. Set the zero setting on the transmitter so that the output current points to 4 mA.
4. Then give the input pressure 100% of the working range of the transmitter.
5. Measure the transmitter output current.
6. Adjust the span setting on the transmitter so that the output current points to 20mA.
7. Provide input pressure of 0%, 25%, 50%, 75%, 100% according to the working range of the transmitter.
8. Record the results on the test form as As Left UP data.
9. Provide input pressure of 100%, 75%, 50%, 25%, 0% according to the working range of the transmitter.
10. Record the results on the test form as As Left DOWN data.
Normalization
1. Remove the multimeter and reattach the transmitter wires to the terminals.
2. Disconnect from the handpump to the transmitter.
3. Connect the pin (impulse piping) of the transmitter to the line.
4. Open the block valve on the high and low sides of the line.
5. Close the bypass valve.
6. Tidy up equipment and clean work area.
>> Calibration Circuit
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