What is a characteristic requirement for centrifugal pumps to operate effectively?

A centrifugal pump is designed to move fluids by converting rotational kinetic energy, typically from a motor-driven impeller, into hydrodynamic energy. For a centrifugal pump to operate effectively, it is essential that the impeller is submerged in the fluid being pumped. This submersion enables the pump to draw water (or other fluids) into the impeller, allowing the pump to create the necessary suction and pressure to facilitate fluid movement.

When the impeller is submerged, it allows for efficient fluid flow into the pump inlet, which is crucial for generating the pressure required for the pump to function properly. If the impeller is not submerged, it may struggle to create sufficient suction, resulting in cavitation, decreased efficiency, and potential damage to the pump. Thus, ensuring that the impeller is submerged in the liquid is a fundamental requirement for the effective operation of centrifugal pumps.