[oil] rotary pump, RP

The (oil) rotary pump rotates a rotor in a case at the hermetic state maintained using oil to aspirate gas molecules into the inlet, and the gas molecules are compressed to open a valve at the outlet, then gasses are ejected to the air. Since the rotary pump operates from atmospheric pressure (10⁵ Pa), the pump is used for rough pumping of a TEM and for evacuation of the back side of the (oil) diffusion pump and the turbo-molecular pump. The working pressure is 10⁵5 to 1 Pa. If a long-time evacuation is continued at the evacuation limit, reflux of the oil vapor of the pump to the vacuum chamber occurs. Thus, the long-time evacuation by the pump should be avoided. When an oil-free pump is required, the scroll pump is used.

Related Term(s)