Klein, Schanzlin & Becker Aktiengesellschaft

Karl-Heinz Becker

Peter Hergt

Alexander Nicklas

Heinz-Dieter Hellmann

Peter Milla

Hans-Dieter Knopfel

Engin Diler

The follow-up guide wheels of a multistage centrifugal pump define flow paths whose cross-sectional area increases exclusively in the axial direction of the respective stages, or axially and radially inwardly, to thus allow for a reduction of the outer diameters of the guide wheels without reducing the efficiency of the pump.

Guide wheel for multistage centrifugal pumps

A centrifugal pump comprises a casing which has two volutes disposed substantially diametrically opposite each other in such a way that the end of the first volute is adjacent to the start of the second volute. The outer diameter of the casing approximates or equals the diameter of the first volute in the region of the end of the first volute. This contributes to compactness of the casing. The volutes surround a rotary impeller or a guide wheel which is installed in the casing downstream of the impeller. Each volute extends along an arc of at most 180 degrees. The casing can have one or more elongated channels extending from the end of the first volute, along the second volute, and to a common outlet nozzle for both volutes.

Centrifugal pump with double volute casing

The double volute casing of a centrifugal pump has a main portion which has first and second volutes extending along arcs of not more than 180 degrees. The outer diameter of the main portion equals or approximates the outer diameter of the end of the first volute, and such end is adjacent to the start of the second volute whose end communicates with an outlet nozzle of the main portion. The latter has two channels which flank the second volute and extend between the end of the first volute and the outlet nozzle. The inner sides of the channels are open and face the axial passage of the main portion. Such inner sides are sealed from the axial passage by tubular inserts which are installed in and are separably fastened to the main portion of the casing. The passage receives a single-suction or a double-suction impeller or a stationary guide wheel which is located downstream of the impeller. The main portion of the casing is a one-piece casting.

Centrifugal pump with open double volute casing

A radial or semiaxial impeller for centrifugal pumps has an annulus of vanes whose inlet edges are disposed at the periphery of a circle and are bounded by convex transition surfaces having small radii of curvature. The inner portions of the suction sides of vanes are bounded by flat or slightly curved surfaces which merge gradually into concave surfaces bounding the outer portions of the respective suction sides. The length of each flat or slightly curved surface is between 3 millimeters and the vane pitch. The ratio of the radii of curvature of transition surfaces at the inlet edges of the vanes to the vane pitch is between 0.0035 and 0.04 and/or the ratio of these radii to the average thickness of the inlet portion of a conventional vane is between 0.04 and 0.50. Such construction of the vanes reduces the likelihood of excessive erosion as a result of cavitation.

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Worms, Germany

Karl-Heinz Becker