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This post was last edited by Zhongyuanren on 2020-7-13 at 17:41. 1. A dry oil-free screw air compressor is a type of twin-screw air compressor; there is no lubricant in its compression chamber, with lubricant only present in the gearbox, making it essentially a dry compressor. The surface of the rotor is coated with a special material, and the male and female rotors do not make actual contact. Since there is no contact in oil-free dry screw compressors, the compression pressure during the first compression stage is not very high; to increase the pressure, two-stage compression is used. The best compression effect is achieved through isothermal compression; however, it is not possible to carry out isothermal compression in practice. Therefore, an intercooler and a drain valve are used after the first stage of compression to reduce temperature and remove water, while a rear cooler is also available after the second stage of compression. 2. The pressure after the first stage of compression is approximately the square root, and this pressure then enters the second stage of compression. Due to the high rotation speed and the high temperature inside the head, the housing of the head is manufactured using the one-time lost foam technique, and the rotor is completely separate. If it is air-cooled, the casing is oil-cooled; if it is water-cooled, the casing is filled with water. Dry oil-free screw air compressors have high maintenance costs.    3. Water-lubricated oil-free air compressors are generally single-screw air compressors. The characteristic of these single-screw water-lubricated oil-free air compressors is that water is used as the medium for lubricating the compressor; a water-based seal is employed, resulting in complete oil-free operation and the production of pure, oil-free compressed air, which has fundamentally changed the production environments in certain industries. Since water is sprayed into the compression chamber, the temperature remains around 40-50 degrees, enabling constant-temperature compression and thus a higher volumetric efficiency; this results in a 15% improvement in efficiency compared to dry, oil-free screw air compressors. Oil-free and water-lubricated screw air compressors have low maintenance costs, as only water, the water filter, and the air filter need to be replaced.

One rotor. No oil spraying for cooling is required during equipment operation

A single-stage compressor means that the air is compressed only once, or in other words, it has just one pair of rotors. An oil-free screw compressor features male and female rotors driven by synchronous gears without them meshing with each other; water or diesel is generally used as the cooling medium