Balancing Arrangements

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  • Balancing flow is passed through the space between its rotating and non-rotating portions when the pump is running. The balancing flow experiences significant throttling as it passes through the gap.

  • This pressure loss produces an axial force to act on the balancing device, counteracting the axial thrust of the impeller and achieving the necessary balance.

  • If the balancing device consists of a balance disc, the entire axial thrust of the pump rotor is usually balanced. In this case, an additional thrust bearing is not required


Fig. 11 Axial thrust: Balancing device with balance drum and thrust bearing
    Balancing device with balance drum
                            
Fig. 10 Axial thrust: Balancing device with balance disc
Balancing device with balance drum
Fig. 12 Axial thrust: Balancing device with double drum and thrust bearing

Balancing device with double drum



 Other Balancing arrangements :

  • Mechanical: complete absorption of the axial thrust via a thrust bearing

  • Design-based: back-to-back arrangement of the impellers 

  • Balancing or reduction of the axial thrust on the individual impeller via Balancing holes

  • Reduction at the individual impeller by back vanes 


Fig. 9 Axial thrust: Axial thrust balancing in a single-stage centrifugal pump with balancing holes only

Balancing holes


Axial thrust balancing in a four-stage pipeline pump with two opposed sets of two series-coupled impellers each
Back-to-back arrangement of the impellers
Fig. 8 Axial thrust: Axial thrust balancing in a single-stage centrifugal pump with back vanes

Back vanes

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