Equipment reference
Multistage pumps
Several impellers act in succession to build head. The complete assembly, pressure limits and first-stage suction conditions matter more than a stage count alone.
Centrifugal stages in series
Liquid passes through successive impellers and return passages. The stage heads contribute to the total head at the same through-flow. Adding stages primarily increases head; it does not multiply the flow through the pump.
Multistage pumps and in-line connections
Horizontal and vertical layouts are possible. Check the shaft, axial-thrust arrangement, seals, bearing support and service access for the chosen construction. Stage count does not establish motor rating, material or external envelope.
A multistage assembly may have in-line nozzles. Nozzle alignment is a pipe-interface choice; the number of stages is a separate hydraulic attribute. Verify both on the actual configuration.
Pressure through the assembly
Compare inlet pressure plus the pressure rise with casing, seal and downstream component limits. Include shut-off and transient conditions. The first-stage suction requirement remains relevant even when the final discharge pressure is high.
High-head duties
Pressure boosting, water transfer and feed duties may use multistage pumps when their curves and materials suit the job. Determine normal and extreme duties, minimum flow, control range and the permitted number of starts before comparing configurations.