A rotary vane pump is a positive-displacement pump that uses a series of vanes installed in a rotating disc or drum to push liquids or gases into smaller volumes, resulting in an increase in pressure. This device is considered a positive-displacement pump because each vane separates a specific volume of gas or liquid and then moves the material into an increasingly smaller space, resulting in flow and pressurization. A rotary vane pump is best suited for low-viscosity liquids and gases, and can be useful as a vacuum pump.
The advantages of a rotary vane pump include good wear characteristics of the vanes if the pumped material is not abrasive and a low parts count because a transmission or gear reduction might not be required. This type of pump also has good performance with gases and low vibration because of its low operating speed. The disadvantages of a rotary van pump include poor durability with abrasive materials and the possibility of vane damage or breakage with thicker materials.
The vanes on a rotary vane pump travel in and out of the rotor as they move around the interior walls of the pump. Centrifugal force or springs can be used to hold the vanes against the outer pump wall. A good seal is required to maintain pump efficiency, and rotary pump vanes will improve in tolerance as they wear against the outer pump wall. Variable pump capacity also can be designed in a rotary vane pump by changing the orientation of the rotor in the pump casing, which results in a different compression ratio from the pump inlet to outlet.
Common uses for a rotary vane pump include hydraulic fluid compression and compressed air pumps in aircraft or trucks. Small rotary vane pumps can be used for drink dispensers, medical dispensing pumps and water pumps on marine engines. The materials used to make the pump and vanes can be modified for high-temperature industrial applications such as furnace air injection or engine turbocharging. Rotary vane pumps work well as vacuum pumps for aircraft applications, laboratory vacuum systems, medical applications and to evacuate and recover refrigerants from air conditioning systems.
Maintenance of a rotary vane pump is relatively simple. Many of these pumps are direct-drive pumps with no gears or transmissions to reduce operating speeds. Periodic inspection of the vanes for wear and vane damage is needed for optimum performance. A shaft seal between the pump and motor might need periodic maintenance but can be eliminated in some cases by the use of a magnetic coupling that uses a sealed magnet inside the pump case driven by a matched magnet on the motor shaft.