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With the development of social science and technology, more and more industries have strict requirements for clean vacuum, environmental protection and so on. They require to avoid the pollution of oil return and oil leakage, so the oil-free vacuum pump has been developed rapidly. Because of the late start, the impression of many enterprise users on oil-free vacuum pump only stays in claw vacuum pump and screw vacuum pump. In fact, the types of oil-free vacuum pump can be more than these.

Speaking of oil-free vacuum pump, the first mentioned is claw vacuum pump. It is a dry vacuum pump developed for electronic semiconductor industry. It can meet the needs of clean vacuum, and has the effect of self opening and closing valve, and has high efficiency.

The second is screw vacuum pump. Screw vacuum pump and claw type vacuum pump are non-contact oil-free vacuum pump, the pump cavity does not contain oil, water and other substances, and there is a gap between the rotors, so it has a certain tolerance to particulate matter and condensable gas. At the same time, compared with the claw vacuum pump, because it does not have the structure similar to the valve, the efficiency is deficient, but its airway is smooth, the rotor structure is simple, and the adaptability is better, so both have advantages over each other.

The development and production of scroll vacuum pump are mainly concentrated in the United States, Japan and the United Kingdom, so many domestic enterprises do not understand this kind of oil-free vacuum pump. Because of its low pumping speed, it is widely used in analytical instruments, semiconductor chip production lines, scientific research equipment, and as the pre stage pump of molecular pumps and small cryogenic pumps.

Roots vacuum pump. There are many kinds of Roots vacuum pump, including wet type, dry type, direct exhaust type, ordinary type, multi-stage Roots, etc., which cause some users' misunderstanding. The mechanical booster pump and multi-stage Roots pump used in medium and high vacuum are actually oil-free vacuum pumps with large pumping capacity and are widely used.

Oil free rotary vane vacuum pump and oil-free piston vacuum pump (reciprocating pump). Although the common rotary vane vacuum pump and piston vacuum pump have oil medium in the pump cavity, they can also realize oil-free operation by using self-lubricating materials, and become oil-free vacuum pumps. In addition, reciprocating pump diaphragm vacuum pump, there is no oil type.

Turbo molecular pump. It is a kind of oil-free vacuum pump originally used in ultra-high vacuum. With the development of high outlet pressure and high flow rate, its application scope gradually develops to the field of medium and high vacuum.

The above are several common oil-free vacuum pump types. In addition, there are also cryogenic pumps, adsorption pumps and other gas trapping pumps that can achieve clean oil-free vacuum environment, but they are usually not included in the oil-free vacuum pumps, so they are not listed here.