Priming Centrifugal Pumps
Most centrifugal pumps are not self-priming. In other words, the pump casing must be filled with
liquid before the pump is started, or the pump will not be able to function. If the pump casing
becomes filled with vapors or gases, the pump impeller becomes gas-bound and incapable of
pumping. To ensure that a centrifugal pump remains primed and does not become gas-bound,
most centrifugal pumps are located below the level of the source from which the pump is to take
its suction. The same effect can be gained by supplying liquid to the pump suction under
pressure supplied by another pump placed in the suction line.