In pump design, which component has an impeller?

• A. centrifugal
• B. positive displacement
• C. axial flow
• D. jet

Answer: (A)

An impeller is the rotating element that transfers energy to the fluid. In pump design, this energy transfer is most closely associated with centrifugal pumps: the impeller spins inside the casing, accelerating the fluid outward and increasing its velocity, which the diffuser or volute then converts into pressure. Positive-displacement pumps move fluid by trapping a fixed volume—using pistons, diaphragms, or gears—without relying on a rotating impeller. Jet pumps generate suction and move water through a jet and entrainment mechanism rather than by an internal rotating impeller. So the component that uses a rotating impeller to impart energy to the fluid is the centrifugal pump.