Multi Stage Canned Motor Pumps (ISO/API685)

CAM
The pump output is delivered through the impellers and diffusers arranged
one behind the other to the pressure nozzle and in this way an increase in
pressure is achieved depending on the number of stages. The partial flow
for cooling the motor and lubricating the slide bearings is tapped off on
pressure side after the last impeller and after flowing through the motor
is lead out again through the hollow shaft between the stages. Since, as a
result, no heated part of the delivery flows back to the suction side considerably
more stable NPSH values are produced in the part load range.
Aggregates of multistage design can therefore be used for considerably
smaller pumping capacities, than pumps of single-stage design.