As the core equipment of industrial compressed air systems, screw air compressors are prone to the common fault of failure to load, which disrupts air supply in production lines. Drawing on frontline operation and maintenance experience, this paper provides practical guidance for on-site technicians. The term "failure to load" refers to a situation where the intake valve fails to open after startup, leaving the unit in an unloaded state.
Troubleshooting is carried out from four core dimensions: control system, intake system, pressure sensor, and pipeline.
For the control system: Check the pressure setting value on the control panel, the input/output points of the PLC, and the communication lines.
For the intake system: Common faults include mechanical jamming of the intake valve and malfunctions of pneumatic components.
For the pressure sensor: This easily overlooked component requires probe cleaning and value testing.
For the pipeline: Conduct air tightness detection and check the pressure difference of the oil separator.
Troubleshooting shall follow the principle of from simple to complex, from electrical to mechanical. Regular maintenance such as cleaning and oil replacement can reduce the fault occurrence rate. It is also recommended to consult professionals when encountering uncertainties. The paper concludes with discussions on related equipment topics and services.
Key Highlights
1. Control System Troubleshooting Priorities
This is the primary starting point for troubleshooting. First, check the pressure setting on the control panel; if it is lower than the actual on-site pressure, adjust it to the range required by the production process. Then, inspect the PLC input/output points and use a multimeter to test whether the relay corresponding to the loading command is energized—relay faults can prevent command transmission. Additionally, pay attention to the communication lines between the control panel and PLC; loose or poor connections can interrupt signal transmission, so fasten line connectors and test communication status.
2. Intake System Fault Types and Solutions
Intake system malfunctions are the most common cause of loading failure. Intake valve faults fall into two categories: mechanical jamming and pneumatic component failure. For mechanical jamming, disassemble the intake valve, clean internal oil deposits and carbon buildup, and check spring elasticity. For pneumatic component failure, test the solenoid valve supply voltage and operation status, and replace aged seals and damaged solenoid valves.
3. Pressure Sensor Troubleshooting
Though easily overlooked, the pressure sensor directly affects the unit’s pressure judgment. A probe covered in oil or a damaged sensor will send incorrect pressure signals. During troubleshooting, first clean the probe, then compare the detected value with that of a standard pressure gauge. Calibrate or replace the sensor promptly if the deviation exceeds the allowable range.
4. Pipeline and Auxiliary Factor Troubleshooting
Severe air leakage in the exhaust pipeline will prevent pressure buildup or cause the unit to cycle between loading and unloading—conduct air tightness tests and repair leakage points immediately. A clogged oil separator will lead to excessively high internal pressure, triggering protection mechanisms. Check the pressure difference of the oil separator and replace the filter element when the value exceeds the limit.
5. Troubleshooting Principles and Daily Maintenance
Adhere to the principle of from simple to complex, from electrical to mechanical to avoid blind disassembly. Daily maintenance—including regular cleaning of air intake filters, lubricant replacement, and inspection of pneumatic component conditions—ensures stable operation of the air compressor and reduces fault risks.