Yes, friction losses due to bearings can be calculated.

The friction will vary with the type of pump and bearings installed. Considering vertically suspended pumps, catalog data published by the manufacturer is based on the bowl assembly, not the complete configured pump. In this case, the inlet case bell and the outlet adapter have to be considered along with the column head losses.

Additional power losses to consider are at the line shaft bearings, thrust bearing friction losses, mechanical seals, gear drives and windage. The overall pump efficiency will be less than the published bowl efficiency due to these losses.  

equation 1

When considering the additional bearing losses, friction losses in bearing spiders and enclosing-tube spiders, which support the line-shaft bearing bushings and enclosing tube, respectively, and transmit the radial forces from the bearing bushings to the outer column vary for different pump manufacturers. These losses have to be supplied by the pump manufacturer.

The manufacturer will also have to provide the losses for vertical electric motors, right-angle gear drives or pump bearing pots supplied with thrust bearings—bearing friction loss will vary with the design and bearing type used.

For the case of a single-row angular contact ball thrust bearing, losses can be estimated by using Equation 1. For more information, refer to ANSI/HI standard 14.3 “Rotodynamic Pumps for Design and Application” at www.pumps.org/standards.

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