Rotary vane: Rotary vane pumps are made up of a number of vanes that are mounted to a rotor that turns in the cavity. As the vanes rotate, centrifugal drive extends them from their individual slots, forming compression cells that get bigger to draw atmosphere in from the consumption and smaller to push air out the exhaust.
Articulated piston: An articulated piston commercial vacuum pump functions in a manner similar compared to that of a car engine. As the piston moves downward in the cylinder, air flow is used through the consumption valve. Through the piston’s upward stroke, the atmosphere is permitted to escape via an exhaust valve. Two spring-backed piston rings are used to seal the piston to the cylinder.
Screw: Rotary screw pumnps include two parallel rotary screws in the pump casing. The screws are synchronized to turn in opposite directions, which in turn causes the compression actions that occurs. The gas is definitely compressed in direction of the pump’s discharge port.
Liquid ring: Liquid ring pumps also operate via positive displacement. Industrial Vacuum Pumps during operation, the pump’s impeller rotates in the pump casing. A rotating liquid ring then seals the impeller and its own blades. Liquid is definitely sucked in to the compression chamber to keep carefully the ring steady. Conveyed gas is usually compressed during each impeller revolution.
Claw: Claw vacuum pumps contain two rotors that are very close but do not are exposed to each other during rotation. As the rotors turn they 
actually enlarge the area between them to attract air, then as they rotate around, physically decrease the space between them to compress the air flow out from the chamber.