1. Nitrogen-Hydrogen Compressor Stage 3 Outlet Pressure Display is Lower Than the Local Pressure Gauge
Fault Inspection
The pressure displayed on the control panel is 0.6 MPa lower than the local pressure gauge. We checked and calibrated both the pressure gauge and the pressure transmitter, and both were accurate. However, the two readings still did not match. After further inspection, it was discovered that the drain valve on the pressure transmitter was leaking.Fault Handling
After replacing the drain valve, the readings on both the pressure gauge and the transmitter became consistent.Maintenance Summary
When the instrument appears to be functioning properly, the focus should shift to checking the pressure lines and accessories. In this case, due to the noisy environment in the plant, the sound of the leaking drain valve was not noticeable. It is recommended to check for leaks in the gas pressure lines by applying soapy water to the joints and pipe openings, which will help identify the leak points.
2. Condenser Tank Vacuum Pressure Display Shows Positive Pressure
Fault Inspection
Upon inspection at the site, the local U-tube manometer showed the normal negative pressure, while the pressure transmitter displayed positive pressure. After verifying that the transmitter was functioning properly, the issue was suspected to be caused by liquid accumulation in the pressure line.Fault Handling
The connection on the pressure line to the transmitter was disconnected for a while, then reconnected. After this, the negative pressure reading returned to normal.Maintenance Summary
The pressure line is connected to both atmospheric pressure and the negative pressure equipment. The negative pressure draws accumulated liquid into the device. Once the pressure line was cleared, the instrument’s display returned to normal.
Conclusion:
For pressure transmitter display errors, thorough inspection and maintenance are crucial for troubleshooting. Regular checks of the pressure lines and their accessories, and addressing leaks and liquid accumulation promptly, can effectively prevent similar issues from occurring.