Abstract: The invention relates to a vertical barrel pump, in which components, constructed as separate inserts in the form of a guide wheel insert, a radially and/or axially developed spiral insert and a diffuser-shaped pressure connecting piece insert are disposed in the region of the last pump stage to improve the efficiency of the multi-stage pump.

Abstract: An impeller for a centrifugal pump has an axis of rotation. The impeller includes a pair of covers which cooperate to define a chamber, and blades in the chamber defining generally radial flow channels. Each of the covers has a wall which is oriented transverse to the axis of rotation. The walls are provided with cutouts at the periphery of the impeller and one cutout is associated with each flow channel. The radial lengths of the cutouts are equal to or less than one-half the lengths of the flow channels. Each flow channel and its respective cutout cooperate to define an aperture which opens to the exterior of the chamber both axially and radially.

Abstract: A casing which admits the fluid medium into the range of the impeller or first impeller in a fluid flow machine, particularly in a centrifugal pump, is made of several sections which have abutting surfaces. At least one such surface has a recess forming part of a fluid flow passage, and the recess is machined into the respective surface by a material removing tool. This simplifies the making of the casing and enables the latter to optimally conform to the conditions of flow between the supply conduit and the impeller or first impeller of the machine to thus reduce noise and stray movements and enhance the efficiency of the machine.

Abstract: A fluid flow machine, particularly a centrifugal pump, wherein the casing has a tubular first portion serving to convey a stream of fluid radially toward a pump shaft which drives one or more impellers. The casing has a second portion with an arcuate band-like wall which spacedly surrounds the shaft and defines a passage having an oval cross-sectional outline and receiving fluid from the outlet of the first portion. A cylindrical outlet of the passage is adjacent the foremost impeller or the only impeller of the pump. One or more guides are provided in the passage to control the flow of fluid from the outlet of the first portion of the casing toward and into the range of the foremost impeller.

Abstract: A radial impeller for use in centrifugal pumps wherein a reduction of the outer diameter entails a change in the total head but does not affect the capacity because the front coverplate of the impeller is inclined with reference to a plane that is normal to the impeller axis. The inclination of the outer marginal portion of the front coverplate with reference to such plane increases in response to decreasing outer diameter of the impeller. The specific speed of the impeller can be increased from approximately 11 to approximately 35 min.sup.-1 by reducing the outer diameters of the coverplates. The exit angles of the vanes are selected in such a way that they remain constant irrespective of the selected outer diameters of the coverplates within the range which is required to change the specific speed from 11 to 35.

Abstract: 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.

Abstract: 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.