Calculation formula for balance force of balance plate in multi-stage pump

Balance discs are commonly used in segmental multi-stage pumps, installed after the last stage impeller and rotating together with the rotor. There are two clearances in the balance device, one is the radial clearance formed by the outer circle of the shaft sleeve, and the other is the axial clearance formed by the inner end face of the balance disk. The balance chamber behind the balance disk is connected to the pump suction port. The balance plate works by generating pressure difference through leakage, which means there is no balance force. But efforts should be made to generate a large balance force with minimal leakage. The leakage rate of the general pump balance plate is 3% to 8% of the rated flow rate.

The calculation of balance force is very important and plays a key role in the hydraulic design of the balance plate. The calculation method and formula for balance force are as follows.