What is the difference between a self-priming and a centrifugal pump?

Centrifugal pumps do not have seals between the suction and discharge sides, which means they are not self-priming and cannot remove air or gases if the pump is above the fluid level.

In water systems, this means a self-priming pump doesn’t need to be installed below the water tank — it can operate horizontally or above the fluid level and still draw water effectively.