Impeller pump with self-priming column attachment

Claim 1

The combination of a motor-driven centrifugal pump assembly including an impeller housing with an inlet as the base thereof, an impeller within said housing facing said inlet, and a motor including an output shaft disposed above the impeller housing, said output shaft extending into and being drivingly connected to said impeller, a self-priming column attachment detachably secured to the pump assembly including an elongate hollow column having its upper end secured to the impeller housing with the interior of the column connecting with said inlet, an elongate shaft extension extending axially within said column with a detachable connection between the upper end of said shaft extension and said output shaft, bearing means rotatably supporting said shaft extension within said column adjacent the bottom end of the column, and an axial flow inducer within said column connected to said shaft extension, said impeller housing having walls defining a double-volute impeller chamber enclosing the impeller within the housing, and a balance chamber disposed upwardly of and behind the impeller receiving fluid under pressure from the impeller, and a balance line conduit connected at its upper end with said balance chamber and extending to an open, lower end disposed at substantially the level of said axial flow inducer, said double-volute chamber serving to radially balance said output shaft in the region of said connection between said shaft extension and said output shaft and said balance line conduit serving to axially balance said shaft extension which extends from said connection.