Abstract: A centrifugal pump includes at least one impeller (4) and at least one sealing arrangement arranged between the impeller (4) and a housing wall. The sealing arrangement seals a suction side of the impeller (4) with respect to a pressure side of the impeller (4). The sealing arrangement including a seal (12) fastened on the impeller (4) in a rotationally fixed manner.

Abstract: A rotary encoder comprising a magnet, AMR or GMR sensors and an evaluation means. The AMR or GMR sensors are arranged to generate two signals that unambiguously encode the rotary position of the magnet within a predetermined range of rotary positions and a direction of rotation of the magnet. The evaluation means is arranged to derive single-turn and multi-turn information solely from the signals. The encoder is arranged to be switched to a power saving state for a predetermined period of time, to be at least partially reactivated thereafter and to compare a current value derived from the signals with a stored previous value derived from the signals.

Abstract: A centrifugal pump includes at least one impeller (4) and at least one sealing arrangement arranged between the impeller (4) and a housing wall. The sealing arrangement seals a suction side of the impeller (4) with respect to a pressure side of the impeller (4). The sealing arrangement including a seal (12) fastened on the impeller (4) in a rotationally fixed manner.

Abstract: A rotary encoder comprising a magnet, AMR or GMR sensors and an evaluation means. The AMR or GMR sensors are arranged to generate two signals that unambiguously encode the rotary position of the magnet within a predetermined range of rotary positions and a direction of rotation of the magnet. The evaluation means is arranged to derive single-turn and multi-turn information solely from the signals. The encoder is arranged to be switched to a power saving state for a predetermined period of time, to be at least partially reactivated thereafter and to compare a current value derived from the signals with a stored previous value derived from the signals.

Abstract: The centrifugal pump unit includes a flow switch arranged within the pump housing in the flow path of a delivery fluid, which essentially consists of an electromagnetic switch device and a two-armed, pivotably mounted lever whose one arm projects into the flow path and whose other arm carries a magnet which is in contact-free active connection with the switch device. The switch device is arranged within a terminal box mounted on the unit housing. The lever is seated within a switch housing which is incorporated in a cartridge-like manner into the pump housing and which is hermetically sealed to the outside and which is arranged neighbouring the terminal box that such it is only in magnetic active connection so that the reed contact located in the terminal box is controlled by the magnet located in the switch housing. In this manner a usual terminal box may be used which does not need to be sealed with respect to the delivery flow.

Abstract: In operating high-pressure cleaning units, the outflow of the water discharged from the associated pump (6,8) may be temporarily interrupted. As the pump normally operates continuously, care must be taken to ensure that the water can then be returned in a bypass to the pump's suction side. This can be achieved by a bypass valve sensing a rising pressure in the said closing situation, thus opening for the bypass. Correspondingly, the bypass valve (36,44,32) senses a declining pressure when the discharge or ejection is resumed, thus causing a block to the bypass (40). However, a corresponding, declining pressure occurs when the pump is stopped, for which reason the bypass valve will block the bypass also in this condition. Thus, the result is that during the stopping process determined by the pump's inertia a substantial and dangerous pressure may build up in the discharge conduit (26) from the pump.