How to calibrate Yokogawa pressure transmitter?

Here are the general steps to calibrate a Yokogawa pressure transmitter:

Preparation

• Gather equipment: You need a precision pressure calibrator (with an accuracy at least three times higher than the required accuracy of the transmitter), a multimeter (to measure the current output), a suitable pressure source (such as a pressure pump or a standard pressure module), and necessary connecting cables and fittings.

• Check the environment: Make sure the calibration environment meets the operating requirements of the pressure transmitter in terms of temperature, humidity, etc., to avoid environmental factors affecting the calibration results. Also, confirm that the pressure transmitter is firmly installed and there are no loose or leaky connections.

Zero - point calibration

• Connect the devices: Connect the pressure calibrator to the pressure transmitter correctly, and connect the pressure source to the pressure - inlet of the pressure transmitter through an appropriate pipeline. Ensure a tight and leak - free connection.

• Evacuate the pipeline: If there is pressure in the pressure transmitter before calibration, open the vent valve or relevant device to evacuate the gas or liquid in the pipeline so that the pressure transmitter is in a zero - pressure state.

• Set the calibrator: Set the output of the pressure calibrator to zero - pressure value.

• Adjust the zero point: Enter the calibration mode of the pressure transmitter (the specific operation may vary depending on the model, refer to the transmitter's manual). Use the zero - adjustment button on the transmitter or a handheld communicator and other tools to adjust the zero - potentiometer so that the output current of the pressure transmitter is 4mA (for a 4 - 20mA output transmitter). During the adjustment, observe the reading of the multimeter and make sure it is stable around 4mA.

Span calibration

• Apply the standard pressure: Use the pressure source to apply the full - span standard pressure value to the pressure transmitter. For example, if the range of the pressure transmitter is 0 - 100kPa, apply 100kPa of pressure.

• Set the calibrator: Set the output of the pressure calibrator to the value corresponding to the applied standard pressure value.

• Adjust the span: In the calibration mode of the pressure transmitter, adjust the span potentiometer so that the output current of the pressure transmitter is 20mA (for a 4 - 20mA output transmitter). Again, observe the reading of the multimeter and ensure it accurately reaches 20mA.

Intermediate - point calibration

• Apply intermediate pressures: After the zero - point and full - span calibration are completed, select some intermediate pressure points, such as 25%, 50%, and 75% of the range pressure values. Use the pressure source to apply these pressures in turn.

• Check the output: Observe whether the output current of the pressure transmitter at these intermediate pressure points is within the allowable accuracy range. If it is out of the accuracy range, you may need to readjust the zero - point and span until the output at all points meets the accuracy requirements.

Verification and recording

• Repeat the test: Start from the zero - point again, and gradually apply different pressure values to check whether the output of the pressure transmitter is stable and accurate. You can repeat the test several times to ensure the reliability of the calibration results.

• Record the data: Record the data such as the applied pressure values and the corresponding output current values of the pressure transmitter during the calibration process as part of the calibration report. These data are of great reference value for future maintenance, troubleshooting, and recalibration.

It should be noted that different models of Yokogawa pressure transmitters may have some slight differences in specific calibration operations. Therefore, before calibration, be sure to carefully read the transmitter's manual and follow the instructions in it. If you are not familiar with or unsure about the calibration process, it is recommended to seek the help of professional technicians.