For a single pump axial force balance generally have the following forms:
1. Opening balance hole :
Drill several holes near hub in the pump rear end and in back add a sealing ring, sealing ring and the impeller inlet diameter equal to the outer diameter. When the pump is working between the sealing ring within the liquid suction port and communicated with the pressure and suction pressure. The sealing ring between the area and the area of the front cover of the extraoral inhalation is equal to the total force, and sent the liquid pressure in front and rear cover is basically the same, the axial force is not balanced by a small part of the bearing. Under normal circumstances, the effect of balancing the axial force is better. The characteristic is that the leakage is more, the liquid of the balance hole is disturbed the normal flow of the liquid in the impeller inlet, the efficiency of the centrifugal pump is reduced by about 2-5%, and the liquid pump is only suitable for small single stage centrifugal pump.
2. The balance tube :
This method is basically the same with a balance hole, and the suction impeller plate in the corresponding setting ring, using the balance tube this sealed space inside the liquid into the pump inlet, so this part of the entrance pressure and hydraulic balance, so that the balance of axial force, 4-5 times of this kind of device requires balance tube the flow area should be equal to or greater than the ring gap flow area.
3. Using balanced blade :
On the back of the placement of several symmetric impeller hub radial ribs, when the leaves turn, rib like pump blade to blade liquid speed rotation, centrifugal force increases, the blade pressure decreased significantly, so that the pressure on both sides of the impeller to balance the balance depends on the balance of leaf size and leaf with the pump clearance. The disadvantage is that the pump efficiency is reduced.
4. Double suction impeller ;
With both sides of the impeller inlet in single stage centrifugal pump with large flow or a multistage centrifugal pump, axial thrust from its own operating conditions to be balanced, but because the manufacturer is very difficult to pump on both sides of the flow part geometry is completely consistent, the axial force so there will still be smaller on the rotor, so bear, by single row radial ball bearing shaft end.
In addition, the multi-stage pump impeller axial balance device can be used symmetrically, balance the axial force balance and balance disc hub axial force balance etc..
