In the daily use of air compressors, various problems often occur. By learning the causes of other people's maintenance and diagnosis of air compressor failures, we can accumulate experience, and when the air compressor fails,
It is easier to determine where the fault lies.
The following editors have compiled a number of common faults and maintenance ideas for air compressors for everyone to learn together.
1. Air compressor over temperature alarm and stop
The air compressor alarmed and stopped when the temperature was too high. After trying to restart it, it only worked for a short time, and the temperature rose instantly. When it exceeded 100°C, the alarm stopped. The frequency of such failures is not very high, 2 to 3 times a day.
No open circuit was found by measuring the thermocouple with a multimeter, and no problem was found by checking the digital temperature controller.
Replaced a digital temperature controller, and the fault remains the same.
Remove the thermocouple for inspection, and find that the node of the thermocouple has signs of open welding. When measuring the thermocouple with a multimeter, touch the node of the thermocouple with the other hand, and the multimeter shows an instantaneous disconnection phenomenon.
After replacing the new thermocouple, the air compressor is normal.
2. The air compressor rotates normally but there is no pressure
There are generally two types of reasons for this failure: one is the leakage of the pipeline, and the other is the failure of the intake system. There are two possible reasons for the failure of the intake system, namely:
The air filter element is seriously dirty and clogged;
The intake valve is not open;
Referring to the analysis of the working principle and electrical principle of the twin-screw air compressor, only the solenoid valve loses power or its internal leakage can cause the intake valve to close.
After inspection, two reasons for pipeline leakage and dirty filter element were ruled out.
When the compressor of the twin-screw air compressor is working, carefully listen to the exhaust sound of the solenoid valve, remove the solenoid valve to check, and find that there is dirt inside, the valve core does not move in place and the pressure is released, causing the intake valve to fail to open. The compressor has no intake air, so no pressure is generated. Clean the solenoid valve and the air compressor runs normally.
3. Time relay damage failure
After the pressure of the air compressor reaches the upper limit of 0.8MPa, the full-load indicator light is on, and the pressure number displayed on the pressure gauge begins to drop, but the compressor motor still does not stop, and the exhaust solenoid valve has acted. When the air pressure drops to the lower limit of 0.5MPa, the gas can be produced again.
At that time, the voltage at the pressure switch was normal. According to the principle analysis, it may be that the time relay did not work, the delay normally closed point could not be disconnected, the compressor motor contactor coil could not be powered off, and the motor would not stop.
Remove the time relay and power up the test, and find that the power supply does not enter the time relay;
Use a multimeter to measure the open circuit of the power pin of the time relay, and the inspection found that the solder joints soldered on the circuit board on the inner side of the pin are open;
After re-welding the solder joints, the installation and test run are all normal;
4. The pressure reaches the upper limit instantly when starting
When the air compressor is commissioned, the pressure gauge shows that the pressure reaches the upper limit instantly, indicating that the compressed air produced by the compressor cannot be discharged.
Careful inspection found that the pressure-retaining valve was stuck, possibly due to the low temperature at that time, and the pressure-retaining valve was frozen.
The pressure-retaining valve was disassembled and checked, and no abnormality was found. After reassembly, the test drive did not appear to be holding back the pressure of the air compressor.
5. Exhaust temperature is too high
The fault phenomenon is that during operation, it trips and stops by itself, and the exhaust high temperature indicator light is on. After inspection, the lubricating oil level meets the requirements, and the lubricating oil is of good quality.
Remove the resistance of the temperature sensor and measure the resistance. There is a deviation between the resistance and the corresponding value of the ambient temperature.
Replacing the sensor resistor, the fault persists after restarting.
After further inspection, it was found that the cooling air volume of the after-cooler heat exchanger of the unit was significantly smaller than the normal operating air volume.
After dismantling the cooler, it was found that oil stains had accumulated in the heat sink. After cleaning, rinsing and drying, the machine returned to normal.
6. Unable to run at full load
After the air compressor is started, the pressure is maintained at about 0.4MPa, and there is no loading or unloading action.
Shut down and check the AC contactor of the control circuit of the loading and unloading valve in the distribution box. The action is sensitive and reliable, and further check that there is no abnormality in the line.
After replacing the pressure switch and restarting the machine, the unit starts to load, but the above fault occurs again after unloading.
After analysis, the loading and unloading solenoid valves have malfunctions, and the manufacturer's technicians require replacement of the solenoid valves.
After disassembly, it was found that the cavity at the connection of the solenoid valve solenoid coil plug-in was full of oil stains. After cleaning, the machine was tested and the machine returned to normal.
7. Fuel injection failure
During the operation of the air compressor, it was found that the lubricating oil was sprayed from the oil filler, and the staff cut off the power in time, but the lubricating oil continued to spray out in a mist form for 3 minutes.
After the fuel injection was stopped, it was found that the sealing ring of the fuel filler was seriously deformed, and the temperature of the screw cavity was very high.
After the standby group cools down naturally, open the oil release valve to release the lubricating oil, and check the oil quality is still good. The maintenance record shows that the lubricating oil has been used for 3060 hours in total, which is within the service cycle.
After further investigation, it was found that a group of fuses in the control circuit of the cooling fan of the rear cooler was burned out. After replacing the fuses, 15L of lubricating oil was added, and the machine returned to normal.
Case: Determination and elimination of invisible computer failure of a screw air compressor
1. Failure phenomenon
The 3# air compressor computer of my air compressor station shows that the pressure of the intercooler is only 1.2bar, which obviously shows that the machine is in an abnormal operating state. Before the failure, the computer always showed that the pressure of the intercooler was about 2.0bar.
The other technical parameter codes of the camera show no major changes compared with the technical parameters before the failure occurred. Basically can be judged as normal.
2. Cause analysis and inspection
According to the technical manual provided by the equipment manufacturer and our work experience analysis and judgment, the possible causes of the failure are as follows:
1. The filter of the air inlet is blocked
After inspection, the computer shows that the filter pressure difference is 0.15bar, which is much lower than the set upper limit of 0.44bar, and the alarm light is not on. In order to confirm the replacement of the new filter test, the fault display remains.
2. Intercooler safety valve leaks
After careful inspection of the intercooler safety valve of the machine, no leakage was found.
3. There is air leakage at the gasket on the pipeline between the low pressure and commercial air compressors
After repeated inspections, no leaks were found.
4. The pipe between the intercooler and the unloader or the low-pressure balance piston is leaking or damaged (the throttle valve is not fully opened), and the compressed air leaks through the high-pressure unloading valve
After repeated inspections, it was not found that the pipes between the intercooler and the unloader or the low pressure balance piston were damaged and leaked. At the same time, we also removed the unloader assembly for cleaning and inspection, and repeatedly pushed the unloading piston by hand. The operation is flexible, the leather cap is intact, and the throttle valve plate is flexibly opened.
5. The pipe leading to the PT18 intercooler pressure sensor is broken and leaked
After inspection, the pipes are in good condition and there is no damage or leakage of rain gas.
6. The PT18 pressure sensor fails,
Replaced the new sensor test, the fault remains.
7. The low-pressure rotor does not work properly
The machine has just been replaced with new high and low pressure rotors. Listening to the sound and checking the vibration, there is no abnormality. And the operation is stable, and the possibility of low-voltage rotor failure can be ruled out based on experience.
3. Troubleshooting
The above reasons can be ruled out from the above analysis. We only suspect that there may be a problem with this computer. Then we removed the 3# computer and exchanged it with the 2# computer. Then we turned on the computer and found that the technical parameters displayed by the 3# computer were normal. In particular, the pressure of the intercooler is displayed as 2.0bar, which is the same as the data displayed by the computer before the machine died, and the failure phenomenon has completely disappeared.
The pressure of the computer intercooler replaced on the 2# machine is displayed as 1.2bar, and other technical parameters are normal.
From this, it can be determined that the 3# machine is caused by a partial failure of the computer, resulting in the distortion of the display parameters. If the computer is replaced, the machine will resume normal operation.