Rotary vane pump

An eccentric rotary vane pump
Another eccentric rotary-vane pump design. Note that modern pumps have an area contact between rotor and stator (and not a line contact).
1. pump housing
2. rotor
3. vanes
4. spring

A rotary vane pump is a type of positive-displacement pump that consists of vanes mounted to a rotor that rotates inside a cavity. In some cases, these vanes can have variable length and/or be tensioned to maintain contact with the walls as the pump rotates.

This type of pump is considered less suitable than other vacuum pumps for high-viscosity and high-pressure fluids[citation needed], and is complex to operate[clarification needed][citation needed]. They can endure short periods of dry operation, and are considered good for low-viscosity fluids[citation needed].