Multistage pumps are defined as pumps in which the fluid flows through several impellers fitted in series, which delivers higher pressure than a normal centrifugal pump with only one impeller.
A horizontal multistage pump is a centrifugal pump containing two or more impellers. The impellers may be mounted on the same shaft or on different shafts, but for the majority of pumps, they are on the same shaft. The fluid flows in relation to the inlet of the pump casing where it flows in relation to the eye of the impeller. The impeller is driven & rotated by mechanical means. The rotation of the impeller creates a centrifugal force that directs the fluid along the impeller vane and pushes the fluid in relation to the outer tip of the impeller vane where it enters the stage diffuser. The diffusers are a type of cutwater that directs the fluid in relation to the suction eye of the next impeller. This process continues until the fluid has passed through each impeller stage. The fluid is then directed out of the pump casing through a final diffuser in relation to the pump discharge. Each stage that the fluid passes through increases the discharge pressure. Multistage pumps are used when higher pressures are required which single-stage pumps of the same size are unable to attain.
- Used for pressure-boosting systems