Abstract: The invention relates to a pumping process for operating a multi-phase screw pump with at least one feed screw surrounded by a housing having at least one inlet on one side and at least one outlet at its top, in which the intake medium is conveyed parallel to the screw shaft in a continuous low-pulsed stream and continuously discharged at the outlet. This invention also relates to a multi-phase screw pump. In order to prevent the drawbacks usually occurring in dry running phases, the invention proposes that a partial liquid volume flow (liquid circulation) be separated on the pressure side and returned in metered quantities into the intake regions and thus kept in circulation.

Abstract: An eccentric screw pump with a pump casing (1) having an intake stub (6) and a delivery stub (7) and enclosing a suction chamber (8) and a delivery chamber (9). A stator (2) arranged in the said casing surrounds a rotor (3) that can be driven by a motor. In order to permit multi-phase delivery, a lower portion (9a) of the delivery chamber (9) is connected to the suction chamber (8) via a liquid bypass line having a valve opening (13) that can be actuated by a control element on the basis of the differential pressure between the delivery and the suction chambers (9, 8) in such a way that the valve (13, 14) is open in the case of the differential pressure which arises in the delivery of dry-running gas but is closed in the case of the differential pressure which arises during the delivery of liquid.

Abstract: Disclosed is an eccentric screw pump for conveying liquids from bore holes, in particular oil well bores. The pump includes an eccentric screw, a stator associated with the screw and located at the lowest point of a riser, and an aboveground drive and bearing unit, the drive shaft of which is connected with a rod linkage by means of a rotating joint which transmits torque and axial force. The rotor is suspended from the rod linkage. For the installation of several conveying units in series and/or of reserve units, several separate stators vertically aligned with each other may be built into the riser and/or several rotors may be placed above each other in the linkage.