⑥ Vortex vacuum pump: Vortex vacuum pump is an oil-free vacuum pump evolved from a vortex compressor.
Among them, screw vacuum pumps, claw vacuum pumps, and vortex vacuum pumps can also be called dry vacuum pumps, which can achieve oil-free sealing.

The second major category is momentum transfer pumps. This imported vacuum pump relies on high-speed rotating blades or high-speed jets to transfer momentum to gas or gas molecules, allowing gas to be continuously transmitted from the pump inlet to the outlet. It can be specifically divided into the following types:
Molecular vacuum pump: It is a vacuum pump that uses a high-speed rotating rotor to transfer energy to gas molecules, causing them to compress and exhaust. It has the following types:
① Traction molecular pump: Gas molecules collide with a high-speed moving rotor to obtain momentum, which is sent to the outlet. Therefore, it is a momentum transfer pump.


⑵ Jet vacuum pump: It is a momentum transfer pump that uses the high-speed jet generated by the pressure drop of the Venturi effect to transport gas to the outlet, suitable for working in viscous and transitional flow states. This type of pump can be further divided into the following types in detail:



⑶ Diffusion pump: a jet vacuum pump that uses low-pressure and high-speed steam flow (such as oil or mercury vapor) as the working medium. Gas molecules diffuse into the vapor jet and are sent to the outlet. The density of gas molecules in the jet is always very low, and this imported vacuum pump is suitable for working in a molecular flow state. It can be divided into:

② Fractional diffusion pump: This type of pump has a distillation device, which allows working liquid vapor with lower vapor pressure to enter the nozzle for high vacuum operation, while working liquid vapor with higher vapor pressure enters the nozzle for low vacuum operation. It is a multi-stage oil diffusion pump.
Diffusion jet pump: It is a momentum transfer pump composed of a single-stage or multi-stage nozzle with diffusion pump characteristics and a single-stage or multi-stage nozzle with jet vacuum pump characteristics in series. The oil booster pump belongs to this type.