Maintenance Procedures for the Three-Stage Filter of an Air Compressor
The three filters of an air compressor primarily refer to the air filter, the oil filter, and the oil‑air separator. Routine maintenance significantly affects the compressor’s service life and operating costs. Please note that when servicing these three filters, pay particular attention to the following points:
Air Filter Maintenance
The air filter is a component that removes dust and contaminants from the incoming air; the filtered clean air then enters the screw rotor’s compression chamber for compression. Because the internal clearances of a screw compressor allow only particles smaller than 15 µm to be captured, if the air filter element becomes clogged or damaged, a large number of particles larger than 15 µm will recirculate within the compressor. This not only significantly shortens the service life of the oil filter and the fine oil‑air separator element but also allows substantial particulates to enter the bearing housing directly, accelerating bearing wear, increasing rotor clearance, reducing compression efficiency, and potentially even damaging the rotor itself.
Maintenance of the oil–gas separator
The oil–gas separator is a component that separates screw compressor lubricating oil from the compressed air. Under normal operating conditions, its service life is approximately 3,000 hours; however, the quality of the lubricant and the filtration accuracy of the intake air significantly affect its lifespan. Consequently, in harsh operating environments, the maintenance and replacement interval for the air filter element should be shortened, and installing a pre‑filter may even be necessary. The air filter element must be replaced when the pressure drop exceeds 0.12 MPa; otherwise, motor overload, damage to the oil–gas separator, and oil leakage may occur.
Oil Filter Maintenance
After the new machine has run for 500 hours, the oil filter element should be replaced, and the oil filter cartridge must be removed using a dedicated wrench. Before installing the new filter, it is advisable to apply some screw‑thread lubricant, then use both hands to screw the sealed filter back onto the oil filter housing and tighten it firmly. It is recommended to replace the filter every 1,500–2,000 operating hours. When changing the oil, the oil filter should also be replaced at the same time; in harsh operating conditions, the replacement interval should be shortened. Do not exceed the prescribed service life of the oil filter; otherwise, severe clogging may cause the differential pressure to surpass the bypass valve’s allowable limit, triggering automatic opening of the bypass valve. This will allow large amounts of contaminants and particulates to enter the screw‑type compressor directly, resulting in serious damage. For diesel‑engine‑driven units, the replacement of the diesel fuel filter and the diesel engine oil filter shall follow the diesel engine’s maintenance schedule, with replacement procedures similar to those for the screw‑type oil filter.
Replacement procedure: Remove all control pipe fittings mounted on the oil–gas tank cover. Extract the return oil line that extends into the oil–gas tank, and unscrew the fastening bolts securing the tank cover. Disassemble the upper cover of the oil–gas tank and remove the oil sludge. Clean off the asbestos gasket and any dirt adhering to the upper cover plate. When installing a new oil–gas separator, ensure that the upper and lower asbestos gaskets are securely fastened; during compression, the gaskets must be neatly aligned, as misalignment can lead to gasket damage. Reinstall the upper cover, the return oil line, and the control lines in their original positions, and check for leaks.
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