The design of the Mercury Electronic Library

A self-priming centrifugal pump having an inlet leading to a rotary impeller which has a given axis of rotation. The impeller is surrounded by a fluid guide which is located in a housing provided with an outlet through which fluid is discharged from the pump. The fluid guide is formed with a gap situated in a plane which is perpendicular to the above axis so that during self-priming operations liquid can return back toward the axis of the impeller through the latter gap.