Positive Displacement Pumps are classified into two general categories and then subdivided into four/five categories each:
Vane - The vane(s) may be blades, buckets, rollers or slippers which cooperate with a dam to draw fluid into and out of the pump chamber.
Piston - Fluid is drawn in and out of the pump chamber by a piston(s) reciprocating within a cylinder(s) and operating port valves.
Flexible Member - Pumping and sealing depends on the elasticity of a flexible member(s) which may be a tube, vane or a liner.
Single Screw - Fluid is carried between rotor screw threads as they mesh with internal threads on the stator.
Progressing Cavity - Fluid is carried between a rotor and flexible stator.
Gear - Fluid is carried between gear teeth and is expelled by the meshing of the gears which cooperate to provide continuous sealing between the pump inlet and outlet.
Lobe - Fluid is carried between rotor lobes which cooperate to provide continuous sealing between the pump inlet and outlet.
Circumferential Piston - Fluid is carried in spaces between piston surfaces not requiring contacts between rotor surfaces.
Multiple Screw - Fluid is carried between rotor screw threads as they mesh.
Positive Pump Tutorial Topics