Interstage casing for a pump made of sheet metal.

摘要

A multistage centrifugal pump has a plurality of series-connected interstage casings of pressed sheet metal housing respective impellers. Each of the interstage casings includes a cylindrical side wall for housing an impeller, a bottom wall joined to the cylindrical side wall and extending around an inlet for the impeller, and a return blade attached to the bottom wall remotely from the impeller. The bottom wall has a central region projecting conically or spherically radially inwardly toward the impeller by a distance corresponding to the extent to which the bottom wall is deformable under an interstage pressure difference. The deformation of the bottom wall that is developed under the pressure generated by the impeller is borne by the casing body itself only, without affecting the welded spots, which are prevented from being ripped off under stresses that would otherwise concentrate on the welded spots.