What happens to the discharge of a centrifugal pump when the head is increased?

In the context of centrifugal pumps, as the head — which represents the pressure energy that the pump can generate to lift the fluid — is increased, the natural behavior of the pump’s hydraulic performance is to reduce the flow rate or discharge. This is generally illustrated by the pump curve, where as the resistance (head) against which the pump is working rises, the volume of fluid being moved (discharge) decreases.

Centrifugal pumps operate on the principle of converting rotational energy, typically from an electric motor, into kinetic energy in the fluid. When an increase in head occurs, the pump must do more work to push the fluid against greater resistance, effectively directing more energy into overcoming the pressure rather than maintaining a high flow rate.

In practical terms, if the system requires a higher head and the pump's capability reaches a point where it cannot maintain the same discharge, the relationship between head and discharge illustrates this characteristic. This is a common scenario seen in various pump applications, meaning the operational efficiency hinges upon understanding these interactions between head and discharge for proper system design and functionality.