Rotary positive displacement pumps

[큰나무]

These pumps move fluid using a rotating mechanism that creates a vacuum that captures and draws in the liquid^{[citation needed][dubious – discuss]}.

Advantages: Rotary pumps are very efficient^{[citation needed]} because they naturally remove air from the lines, eliminating the need to bleed the air from the lines manually.

Drawbacks: The nature of the pump requires very close clearances between the rotating pump and the outer edge, making it rotate at a slow, steady speed. If rotary pumps are operated at high speeds, the fluids cause erosion, which eventually causes enlarged clearances that liquid can pass through, which reduces efficiency.

Rotary positive displacement pumps fall into three main types:

• Gear pumps - a simple type of rotary pump where the liquid is pushed between two gears
• Screw pumps - the shape of the internals of this pump is usually two screws turning against each other to pump the liquid
• Rotary vane pumps - similar to scroll compressors, these have a cylindrical rotor encased in a similarly shaped housing. As the rotor orbits, the vanes trap fluid between the rotor and the casing, drawing the fluid through the pump.