How to distinguish between oil-free and oil-based compressors
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There is a twin-screw exhaust compressor in my workshop; although it has a lubrication system, the technicians claim it is an oil-free compressor, and there is also spray water used.
The criterion for judgment is whether the medium comes into contact with the lubricating oil; the lubricating oil may only serve to lubricate the bearing parts. Currently, inside a screw compressor, the medium and oil are usually together, and the medium and lubricating oil are separated in an oil separator.
#Here’s a quick reply: #In oil-free screw compressors, the rotors do not come into direct contact with each other; there is a certain gap between them. The male rotor drives the female rotor to rotate through synchronous gears, and these gears not only transmit power but also maintain the required gap between the rotors. The so-called \"oil-free\" concept refers to the situation where the gas does not come into contact with oil at all during compression. However, components such as the compressor’s bearings and synchronous gears still require lubricating oil. Effective shaft seals are used to isolate these lubrication points from the compression chamber. In spray-type screw compressors, a large amount of lubricating oil is injected into the gas being compressed; this oil serves to lubricate, seal, cool, and reduce noise. Spray-type screw compressors do not have synchronous gears – instead, the male rotor directly drives the female rotor to rotate. In addition to lowering the exhaust temperature, the lubricating oil also provides lubrication for frictional parts such as bearings, mechanical seals, and slide valves.