To calibrate a pressure transmitter, follow these general steps:

1. Preparation:

• Ensure that the pressure transmitter is disconnected from the process and the power supply is turned off.

• Gather the necessary equipment: a precision pressure source (e.g., a calibration pump or reference pressure source), a digital multimeter (DMM) or calibrator, and any needed fittings or adapters.

2. Connect the Pressure Transmitter:

• Connect the pressure transmitter to the pressure source (calibration pump) and the measurement device (DMM or calibrator).

• Ensure proper sealing and avoid leaks in the connections to ensure accurate readings.

3. Apply Zero Pressure:

• Start by applying 0 pressure (atmospheric pressure) to the transmitter.

• Adjust the transmitter’s zero setting, if applicable, to ensure that the output signal corresponds to 0 (e.g., 4 mA for a 4-20 mA transmitter).

• Record the output signal value at this point.

4. Apply Span Pressure:

• Next, apply the transmitter’s full-scale pressure (e.g., the highest value the transmitter is designed to measure).

• For a 0-100 psi transmitter, for example, apply 100 psi.

• Adjust the transmitter's span setting so that the output signal corresponds to the expected value (e.g., 20 mA for a 4-20 mA transmitter).

• Record the output signal value at this point.

5. Check Intermediate Points:

• Apply intermediate pressures (e.g., 25%, 50%, and 75% of full scale) and record the corresponding output signal at each point.

• Compare these readings to the expected output values to ensure linearity.

6. Fine-Tune the Calibration:

• If any readings at intermediate points are not within acceptable tolerance limits, adjust the transmitter’s settings to bring the output in line with the expected values.

7. Verify the Calibration:

• Once all adjustments have been made, verify that the transmitter provides correct and linear readings across the full range of pressures.

• Test the device by applying pressures again to ensure the calibration is accurate and consistent.

8. Document the Calibration:

• Record the calibration data, including the applied pressures and corresponding output values.

• Document any adjustments made to the transmitter and any anomalies encountered during the calibration process.

9. Reinstall and Test in the Process:

• After calibration is complete, reinstall the pressure transmitter back into the process, ensuring that all connections are secure.

• Test the transmitter in the field to ensure it performs correctly in real-world conditions.