When the pump dynamic balance, it should be done together with the entire rotor components. Replace the impeller, balance has changed, we need to re-alignment. If it is an ordinary single-stage pump, there is no need to do that, because it has little effect on residual unbalance of the pump. If it is a high-speed pump, or a multi-stage pump, it would need to do the dynamic balance again. For multi-stage pump, make small rotor components installed, do the dynamic balance, then marked location of individual parts, then general assembly the entire pump, in order to achieve the dynamic balance effect.

Pump rotor do dynamic balance conditions: high speed pump should do dynamic balance testing, low speed pump generally only do static balance

Usually if rigid rotor can’t meet the conditions of disc-shaped rotor static equilibrium, it is required to balance the two planes, it is dynamic balance. Only static balance of rotor conditions is as follows (Balancing accuracy G0.4 level is the most accurate, generally static the dynamic balance of the pump impeller selection grade G6.3 or G2.5)

1. single-stage pump, two stage pump rotor, where the operating speed ≥1800 rev / min, as long as the D / b <6, the dynamic balance should be done.

2. And the combination of multi-stage pump rotor (grade 3 or 3 above), regardless of how much speed work should be done in combination rotor balancing. 

3. Generally do not have a single-stage centrifugal pump.

 

4. A large single-stage pump (3000m3 circulating pump) needs to be done.

5. Multi-stage pump must do it.

6. High speed pump must do it.

7. Regular pump impeller has been done static balance before they go out.

Generally, when change the impeller for a single-stage pump, it don’t need to do balancing test again, it should ensure that the replacement impeller has done a balancing test.(After balancing test,if the user has cut impeller diameter, we need to do dynamic balance test again). For multi-stage centrifugal pumps, replaced impeller, the impeller has even done a balancing test, the replacement when the impeller is mounted on the pump shaft, the entire rotor needs re-balancing test, and remember the location of each part, then Remove by location where the balancing test impeller Replace pump.