Piston air compressors use the piston to reciprocate in the cylinder to compress the air. They have high noise and vibration and many wearing parts. After the piston rings are worn, the air volume will decrease causing the decreased efficiency.
The oil-injection screw compressor, an oil-lubricated air compressor, mainly consists of a screw and star wheels to form a compression chamber. The air compression process is completed through the rotation of the screw which has higher requirements for processing accuracy because higher accuracy means higher volumetric efficiency. The noise and vibration are small, the unit has basically no wearing parts so the maintenance cost is low.
The main components of an oil-injected air compressor are the air end, motor, oil and gas separation tank, and cooler. Since the oil requires a higher temperature to ensure its good lubricity, the oil-lubricated air compressor is generally air-cooled. The air is filtered by the filter element and then sucked into the air end for compression.
In an oil-lubricated compressor, lubricating oil is injected into the air end for lubrication and sealing. The compressed oil and gas mixture is separated by the separation core in the oil and gas separation barrel to get compressed air with an oil content of less than 2ppm. After being cooled by the air-cooled cooler, the high-temperature oil returns to the compression air end and circulates continuously.