A centrifugal pump including an outer case; an inner case; a first unit and a second unit placed in fluid communication with each other, each unit including a plurality of impellers; the inner case includes two half-parts joined along a connection plane containing the axis of rotation; a connecting element is placed between the first unit and the second unit, the connecting element is engaged with a last impeller of the first unit and with a last impeller of the second unit.

A centrifugal pump including an outer case; an inner case; a first unit and a second unit placed in fluid communication with each other, each unit including a plurality of impellers; the inner case includes two half-parts joined along a connection plane containing the axis of rotation; a connecting element is placed between the first unit and the second unit, the connecting element is engaged with a last impeller of the first unit and with a last impeller of the second unit.

A non-return valve (19) for a water supply system (1) or a pump (4) is integrated in a flow channel (14) of the water supply system (1). The non-return valve (19) includes a sealing body (21) which is mounted within the channel (14), blocks the channel (14) in a first position forming the closure position and releases the channel (14) in a second position forming the opened position. The sealing body (21) is movably arranged on a holder (31) which includes a closure body (15), with which the holder (31) is releasably fastened in a housing opening.

A non-return valve (19) for a water supply system (1) or a pump (4) is integrated in a flow channel (14) of the water supply system (1). The non-return valve (19) includes a sealing body (21) which is mounted within the channel (14), blocks the channel (14) in a first position forming the closure position and releases the channel (14) in a second position forming the opened position. The sealing body (21) is movably arranged on a holder (31) which includes a closure body (15), with which the holder (31) is releasably fastened in a housing opening.

A well pump includes a plurality of diffusers, wherein each diffuser comprises a first threaded coupling on one longitudinal end and a second threaded coupling on an opposed longitudinal end. An impeller is disposed in each diffuser. The plurality of diffusers are coupled end to end to form a pump housing, in which the first threaded coupling on one diffuser is threadedly engaged to the second threaded coupling on adjacent diffuser.

A well pump includes a plurality of diffusers, wherein each diffuser comprises a first threaded coupling on one longitudinal end and a second threaded coupling on an opposed longitudinal end. An impeller is disposed in each diffuser. The plurality of diffusers are coupled end to end to form a pump housing, in which the first threaded coupling on one diffuser is threadedly engaged to the second threaded coupling on adjacent diffuser.

A method and controller for controlling electrical activation of elements in a system. A method includes identifying (710) a first element (102) of a system (100) by a control system (600), among a plurality of elements (102, 110, 122) of the system (100), that is to be powered. The method includes determining (712) connected elements (110, 122) of the system (100) by the control system (600). The connected elements (110, 122) are connected to deliver power to the first element (102) directly or indirectly, based on an adjacency matrix (400), and the adjacency matrix (400) identifies connections between each of plurality of elements of the system (100). The method includes identifying (714) at least one of the connected elements (110, 122) to activate by the control system (600), based on the adjacency matrix (400), a health table (500), and the connected elements (110, 122), to deliver power to the first element (102). The method includes activating (716) the at least one of the connected elements (110, 122) by the control system (600), thereby delivering power to the first element (102).

A compressor or pump stage is provided. The compressor or pump stage at least comprising a central shaft (8) and one rotor (3), where the axis of rotation of the rotor (3) is the central shaft (8) and where the rotor comprises a number, n, of rows of impellers (5) arranged at an outer perimeter of the rotor with an axial distance between neighbouring rows of impellers (5), where n={2, 3, 4...}.

A self-priming assembly for a multi-stage pump is provided. The self-priming assembly can have a first diffuser, a second diffuser, and an impeller. The first and second diffusers each include a central portion, a diffuser axis, an arcuate channel within the central portion, and a passage extending through the central portion. The first diffuser and the second diffuser are configured to be combined and receive the impeller therebetween with the first diffuser axis, the second diffuser axis, and the impeller axis aligned.

A self-priming assembly for a multi-stage pump is provided. The self-priming assembly can have a first diffuser, a second diffuser, and an impeller. The first and second diffusers each include a central portion, a diffuser axis, an arcuate channel within the central portion, and a passage extending through the central portion. The first diffuser and the second diffuser are configured to be combined and receive the impeller therebetween with the first diffuser axis, the second diffuser axis, and the impeller axis aligned.