1. Open balance holes
     Drill a few holes on the back cover of the pump near the hub, and add a sealing ring on the back cover. The outer diameter of the sealing ring is equal to the outer diameter of the impeller suction inlet. When the pump is working, the liquid in the sealing ring of the back cover is connected with the suction port, and its pressure is similar to the suction port pressure. The area of the rear cover outside the sealing ring is equal to the area of the front cover outside the suction port, so the total force exerted by the pressure of the discharged liquid on the front and rear covers is basically equal, and a small part of the unbalanced axial force is borne by the bearings. Generally speaking, opening a balance hole to balance the axial force has a better effect. Its characteristics are: there is a lot of leakage, and the liquid passing through the balance hole interferes with the normal flow of liquid at the impeller inlet, reducing the efficiency of the centrifugal pump by about 2-5%. It is only suitable for small single-stage centrifugal pumps.

2. Use a balanced tube
     This method is basically the same as the method of opening a balance hole. An orifice ring is installed on the rear cover of the impeller corresponding to the suction inlet. The liquid in the sealed space is introduced into the pump inlet using a balance tube, so that this part of the hydraulic pressure is consistent with the inlet pressure. Balance, so that the axial force is balanced. This device requires that the flow cross-sectional area of the balance tube should be equal to or greater than 4-5 times the flow area of the mouth ring gap.

3. Use balanced blades
     Several radial ribs are symmetrically placed on the back of the impeller rear cover. When the impeller rotates, the ribs act like pump blades to accelerate the rotation of the liquid on the back of the blade. The centrifugal force increases, which significantly reduces the pressure on the back of the blade, thereby causing the impeller to rotate. The pressure on both sides is balanced, and the degree of balance depends on the size of the balancing blade and the gap between the blade and the pump body. The disadvantage is that the pump efficiency is reduced.

4. Adopt double suction impeller
     When an impeller with double-sided water inlet is used on a single-stage centrifugal pump with a large flow rate or a few multi-stage centrifugal pumps, the axial thrust is balanced by its own working conditions. However, in fact, it is difficult for the manufacturer to achieve both sides of the pump. The geometry of the side flow parts is completely consistent, so there will still be a small axial force acting on the rotor. Therefore, it is borne by the single row radial ball bearing at one end of the pump shaft.