INTRODUCTION TO HYDRAULIC BALANCING OF CENTRIFUGAL PUMP – MULTI STAGE

                Hydraulic axial thrust developed in multi stage pump will be sum of the axial thrust acting on the individual impeller which is very high in magnitude. To balance hydraulically for this high magnitude axial thrust, the special hydraulic balancing device used is balancing drum or balancing disc.  In some applications the combination of two balancing devices is used (balancing drum and balancing disc).

Balancing drum, balancing disc and a combination of both is shown in following figures.

 

                                                                        Fig: Balancing drum

                                                                Fig: Balancing disc

                                  Fig: Combination of both balancing drum and balancing disc

Balancing drum

Balancing drum is separated by a small radial clearance from the stationary portion of the balancing device called balancing drum head which is fixed to pump casing.

Balancing disc

Balancing disc is separated by small axial clearance from balancing disc head which is fixed to casing. It is fixed to shaft and rotates with it.

 Further details regarding balancing drum, balancing disc and axial thrust balancing forces in balancing drum and balancing disc in detail will be discussed later.