Multistage Pump
A multistage pump is a centrifugal pump with two or more impellers mounted in series on a common shaft within one casing. Liquid discharged from each impeller passes through a diffuser or return channel to the eye of the next, so the total head developed is approximately the sum of the individual stage heads while the flow remains that of a single stage. This arrangement produces pressures that a single impeller could not achieve efficiently. Configurations include horizontal ring-section, axially split and radially split barrel casings, as well as vertical in-line and vertical can-type designs. Typical services include boiler feedwater, reverse osmosis high-pressure feed, pipeline transfer, mine dewatering, water injection and pressure boosting. Selection considers number of stages, axial thrust balancing, minimum continuous flow and rotor dynamics. API 610 process types include BB3, BB4, BB5 and VS6.
Examples
- Barrel-type boiler feedwater pump
- High-pressure feed pump for seawater reverse osmosis
- Vertical multistage booster pump for building water supply