How the head of a centrifugal pump be increased without replacing the pump itself?

Answer 1

If you could operate a centrifugal pump impeller within a vacuum (to eliminate wind resistance) the edge of the impeller (in a vertical plane) would fling water in all directions including up. The head developed by the pump in feet would be the greatest height the water reached depending on the linear velocity of the liquid leaving the edge of the impeller (like throwing a stone into the air. The liquid's kinetic energy has been converted to potential energy at that elevation, right? To fling the water higher, you must increase the impeller diameter or its rotational speed or both; not possible if you can not replace the pump or its motor.

You can develop more head by reducing some losses. For example if the pump cavitates (forming vapor cavities in the fluid) pumping cooler fluid may help solve the problem. Using the pump for a suction lift from a water level below the eye of the impeller is more prone to cavitation than taking suction from a water level above the eye.

Placing another pump (booster pump?) in series with your pump would produce increased head of the system but must be carefully engineered based on system and pump specs.

Answer 2

Possibly increasing the RPM's or locating it below the source of fluid if possible.