Pump School instructs fluid-handling engineers on positive-displacement rotary pumping principles. As this happens, fluid from the pump inlet fills the void in the rotor created by the extending vane. If excessive vacuum exists at the pump inlet - it will act at the base of the vane. LEGIT Comments will be displayed in 24 hours. This is a Flash Animation of a rotary Vane Pump. Add a comment or brief description of this mechanism in your language. In vane pump designs, the vanes must extend from their retracted position in the rotor during inlet.