Abstract: The invention relates to a submergible multistage pump including a drive unit having an electric motor and a drive shaft. The drive shaft extends in the axial direction, and a hydraulic unit connected to the drive unit and comprising a leading pressure stage, a trailing pressure stage and a top element connected in series. The top element includes an outlet of the multistage pump. The leading pressure stage of the hydraulic unit includes an axial inlet and an axial outlet, a circumferential housing, a circumferential internal diffuser, and an impeller connected to the drive shaft of the drive unit. The housing, the diffuser and the impeller of the leading pressure stage define a flow path from the axial inlet to the axial outlet. The diffuser is connected to the housing. The pump is characterized in that the leading pressure stage includes radial play between the housing and the diffuser in the radial direction, and abutment between the housing and the diffuser in the axial direction.

Abstract: A method for controlling a drainage pump configured to operate at a variable operational speed, and a drainage pump assembly so controlled. The drainage pump has a drive unit including an electrical motor and a drive shaft, and a hydraulic unit with an impeller operatively connected to the electrical motor via the drive shaft. The method includes continuously operating the drainage pump at a positive operational speed with default operation at a predetermined idle operational speed, and intermittently detecting whether the drainage pump is snoring or not snoring. The operational speed is decreased by one step when snoring is detected, and increased by one step when snoring is not detected.

Abstract: A pump having a drive unit with an electric motor, a hydraulic unit connected to the electric motor, and an integrated control unit operatively connected to the electric motor and configured for monitoring and controlling the pump. An integrated pressure sensor, connected to the control unit, has a fixed reference pressure. The control unit determines a liquid level of a liquid surrounding the pump based on a relation between an actual value of the pressure sensor and a reference value. A method for calibrating the pump comprises initiating pumping, continuing pumping until the liquid level is equal to a predetermined calibration level, determining the actual pressure value when the liquid level is equal to the predetermined calibration level, and calibrating the pump by setting a new reference pressure value corresponding to the actual pressure value.

Abstract: A pump having a drive unit with an electric motor, a hydraulic unit connected to the electric motor, and an integrated control unit operatively connected to the electric motor and configured for monitoring and controlling the pump. An integrated pressure sensor, connected to the control unit, has a fixed reference pressure. The control unit determines a liquid level of a liquid surrounding the pump based on a relation between an actual value of the pressure sensor and a reference value. A method for calibrating the pump comprises initiating pumping, continuing pumping until the liquid level is equal to a predetermined calibration level, determining the actual pressure value when the liquid level is equal to the predetermined calibration level, and calibrating the pump by setting a new reference pressure value corresponding to the actual pressure value.

Abstract: A method for controlling a drainage pump configured to operate at a variable operational speed, and a drainage pump assembly so controlled. The drainage pump has a drive unit including an electrical motor and a drive shaft, and a hydraulic unit with an impeller operatively connected to the electrical motor via the drive shaft. The method includes continuously operating the drainage pump at a positive operational speed with default operation at a predetermined idle operational speed, and intermittently detecting whether the drainage pump is snoring or not snoring. The operational speed is decreased by one step when snoring is detected, and increased by one step when snoring is not detected.

Abstract: A drainage pump assembly includes a drainage pump and an outlet conduit connected to the drainage pump. The drainage pump includes a pump chamber and is configured to pump liquid having solid matter. The outlet conduit includes a sedimentation trap having an inlet opening, an outlet opening and a belly located between the inlet opening and the outlet opening. A first conduit extends between the pump chamber of the drainage pump and the belly of the sedimentation trap. The first conduit includes a non-return valve. The outlet opening of the sedimentation trap is configured to be connected to a second conduit.