Canned Motor Pump Type CNF

To cool the motor and lubricate the bearings, a portion of the flow is branched off at the periphery of the impeller and returned to the pressure side after flowing through the motor. 

An auxiliary impeller serves to compensate for hydraulic losses that arise this way. Due to the partial flow return to the pressure side, point 3 in the pressure-temperature diagram corresponding to the largest heating has sufficient distance from the boiling curve.

Under otherwise identical conditions, it is, therefore, possible to use the CNF model for pumping liquid gases with an extremely steep vapour pressure curve.