A rotary vane vacuum pump works by using centrifugal force to turn blades against the circular surface of a cylinder whereby pockets of air are pushed from an inlet port to an outlet port as air pressure increases. Air pressure changes from the inlet port to the outlet port because the volume of air decreases inside the cylinder when the blades turn.
A rotor is positioned closer to the top of the cylinder of the pump. Blades attached to the rotor create a specific volume of air at the inlet port. The rotor turns and the volume of air is pushed along a circular motion towards the outlet port. Air pressure increases due to a smaller chamber closer to the outlet port. When air pressure reaches maximum levels, the air is forced out of the pump. The process starts over when the blades return to the inlet port.
Rotary vane vacuum pumps are used for freeze drying, process engineering and chemical analysis, according to Pfeiffer Vacuum. Some rotary vane vacuum pump models require oil lubricants to reduce friction. Other pumps stop the back flow of air into the system to achieve maximum air pressure. Safety valves can be installed so air pressure is relieved when a pump ceases operation.