Abstract: An impeller assembly for centrifugal pumps has two disk members that have different diameters, are arranged coaxially to a rotation axis and face each other so as to form an interspace; blades are radially arranged in the interspace; the two disk members are also centrally provided with a fastening means for fastening to a transmission shaft, which rotates about the rotation axis. The particularity of the present invention resides in having contoured vanes that protrude radially from the peripheral region of the disk member that has the smallest diameter and are arranged substantially at the blades.

Abstract: An impeller assembly for centrifugal pumps has two disk members that have different diameters, are arranged coaxially to a rotation axis and face each other so as to form an interspace; blades are radially arranged in the interspace; the two disk members are also centrally provided with a fastening means for fastening to a transmission shaft, which rotates about the rotation axis. The particularity of the present invention resides in having contoured vanes that protrude radially from the peripheral region of the disk member that has the smallest diameter and are arranged substantially at the blades.

Abstract: A method of detecting stall in an axial fan through acoustical measurements in air the air flow, includes measuring the sound emanating from the flow adjacent the fan, preparing a visual representation of the sound, comparing the visual representation with a library of fixed visual representations derived from a plurality of tests representative of the performance of the fan under a range of operating parameters, selecting the fixed visual representation most closely matching the visual representation of the said sound, and deriving a control signal from the selected fixed visual representation. The visual representations are formed by a symmetrised dot pattern (SDP) technique.

Abstract: A method of detecting stall in an axial fan through acoustical measurements in air the air flow, includes measuring the sound emanating from the flow adjacent the fan, preparing a visual representation of the sound, comparing the visual representation with a library of fixed visual representations derived from a plurality of tests representative of the performance of the fan under a range of operating parameters, selecting the fixed visual representation most closely matching the visual representation of the said sound, and deriving a control signal from the selected fixed visual representation. The visual representations are formed by a symmetrised dot pattern (SDP) technique.