A rotary pump operates by trapping fluid within rotating components (rotors, vanes, gears, or lobes) and moving it from the suction side to the discharge side of the pump, creating a continuous flow. Unlike reciprocating pumps, this results in a relatively steady, non-pulsating flow.
Here's a more detailed breakdown of the process:
-
Fluid Enters: As the rotating element(s) (rotor, gears, vanes, etc.) turn, they create an expanding cavity on the suction side of the pump. This expanding cavity draws fluid into the pump.
-
Fluid Trapped: The rotating element(s) then trap a fixed volume (or pocket) of the fluid within the pump housing. The exact mechanism for trapping varies depending on the type of rotary pump (gear pump, vane pump, lobe pump, etc.).
-
Fluid Transported: The trapped fluid is carried around the inside of the pump casing by the rotating element(s). During this rotation, the fluid is physically moved from the suction side towards the discharge side of the pump.
-
Fluid Discharged: As the rotating element(s) continue to turn, the trapped fluid is forced out of the pump through the discharge port. The volume of the cavity decreases as it approaches the discharge, pressurizing the fluid.
Key Features and Advantages:
- Positive Displacement: Rotary pumps are positive displacement pumps, meaning they displace a fixed volume of fluid with each revolution. This allows for accurate and predictable flow rates.
- Self-Priming: Many rotary pump designs are self-priming, meaning they can draw fluid into the pump even if there is no fluid initially present.
- Steady Flow: Rotary pumps deliver a relatively smooth, non-pulsating flow compared to reciprocating pumps.
- Handle Viscous Fluids: They are often well-suited for handling viscous fluids, like oils, due to their design.
Types of Rotary Pumps:
| Type of Rotary Pump | Mechanism |
|---|---|
| Gear Pump | Two meshing gears trap and move fluid. |
| Vane Pump | Vanes slide in and out of a rotor, trapping fluid. |
| Lobe Pump | Two or more lobes rotate, trapping fluid between them and the casing. |
| Screw Pump | Screws rotate to move fluid along the axis of the screw. |
| Circumferential Piston Pump | Rotating pistons trap and move fluid. |
In summary, rotary pumps use rotating components to trap fluid, move it from the suction to the discharge side, and create a continuous flow. Their positive displacement nature and ability to handle viscous fluids make them suitable for various applications.
