The partial flow for cooling the motor and lubricating the slide bearings will be diverted at the periphery of the impeller and, after having passed through the motor, is recirculated to the discharge side . An auxiliary impeller is used to overcome the hydraulic losses encountered along the way . The recirculation of the partial flow towards discharge side ensures that the heated motor cooling flow has sufficient excess pressure above the boiling point of the pumped liquid during re-entry into the pump . This pump design can be used for liquefied gases with an extremely steep vapour pressure curve