The principle of centrifugal pump is simply that when the impeller rotates at high speed, it drives the liquid between the blades to rotate. Due to the centrifugal force, the liquid is thrown from the center of the impeller to the outer edge of the impeller, and the kinetic energy increases accordingly. When the liquid enters the pump casing, due to the gradual expansion of the flow channel in the volute shaped pump casing, the liquid flow velocity gradually decreases, and a part of the kinetic energy is converted into static pressure energy, so the liquid flows out along the discharge outlet at a higher pressure. Due to the fact that centrifugal pumps mainly rely on centrifugal force to transport liquids, they are called centrifugal pumps. If not handled properly, the centrifugal force generated by the impeller can cause the pump to vibrate and produce abnormal noise.

If abnormal vibration and noise are found during the use of a centrifugal pump, it should be stopped immediately for inspection.

1. Is the pump foundation reliable

When vibration occurs, the first thing to check is whether the foundation bolts of the centrifugal pump are tightened. If not tightened, it will cause vibration of the centrifugal pump. We also need to consider whether the strength of the foundation is sufficient. Sometimes, due to design reasons, a soft foundation can also cause vibration.

2. Align the coupling

Many centrifugal pumps are driven by couplings, and there are also many types of couplings. The proper alignment of a conventional three jaw coupling directly affects the normal operation and service life of the coupling, shaft, bearing, mechanical seal, and other components.

3. Find Center

Misalignment of the center is also a common cause of vibration, and it must be strictly adjusted within the specified range according to the standards.

4. Bearing inspection.

Is there any problem or damage with the installation of the bearings.

5. Adjust the center position of the rotor.

The rotor of the water pump should be concentric with the stator, otherwise friction and vibration will occur during the operation of the water pump.

6. Shaft bending and rotor measurement

If the cause of the vibration cannot be found externally, the water pump can only be disassembled. First, measure and calibrate the shaft bending. If there are no problems, then assemble the rotor and measure the overall sway and deflection. If it exceeds the standard, it must be calibrated.

7. Dynamic and static balance detection.

After disassembling the centrifugal pump, in order to avoid vibration when starting the pump, the impeller should also undergo a static balance test.

The impact of external conditions on the water pump.

When all possible problems with the water pump itself have been eliminated, and the vibration problem still cannot be solved, the impact of external conditions on the water pump should also be considered. For example, resonance caused by the natural frequency of the water pump foundation being similar to the vibration frequency, vibration of the water pump caused by the failure of the prime mover, and the use of strong alignment in the connection between the pipeline and the water pump can also cause abnormal vibration of the water pump. Generally, taking corresponding measures can solve the problem.

Shanghai Boyang Pump Factory

Technical Department