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Some impellers of slurry pumps have balance holes, so what is a balance hole and what is its function？

The balance hole, also called the return port, is mainly to balance the axial force generated by the impeller when it is working, reduce the wear of the bearing end face and the wear of the thrust plate. The center is thrown around the impeller along the flow channel between the blades. Because the liquid is affected by the blades, the pressure and speed increase at the same time, and a forward axial force is generated. The impeller is punched to reduce the shaft generated by the impeller. to force. It plays a role in protecting bearings, thrust plates and controlling pump pressure.

The degree of reducing the axial force depends on the number of pump holes and the size of the hole diameter. The sealing ring and the balance hole are complementary to each other. The disadvantage of using this balancing approach is the loss of efficiency. Generally, the leakage of the balance hole is generally about 2%-5% of the design flow.

In addition, the leakage flow through the balance hole collides with the main liquid flow entering the impeller, which destroys the normal flow state and reduces the cavitation performance. At non-rated flow, the flow state changes. When the flow rate is small, due to the influence of pre-rotation, the pressure in the central part of the impeller inlet is lower than the peripheral pressure, and the leakage through the balance hole increases. Although the lift increases, the pressure in the lower cavity of the seal ring is still very low, so the axial force is further reduced. Small. When the flow is large, the axial force is also reduced due to the drop of the lift.