Pump Troubleshooting Guide——Water Pump Abnormal Vibration

Continued from the last article about the pump troubleshooting guide and we explained how to identify the reason of abnormal noises and way to solve them.

Today we will keep moving to the part — the abnormal vibration. 

1.Not Fixed

Reason:

The water pump is not fixed tightly and vibrates during running. It collides with the foundation which increases the vibration degree.

Manifestation:

Noise originates from the location between the pump and the foundation.

The water pump is not properly fixed.

Persistent crashing sound.

How to Judge:

Press and hold the water pump, the noise drops or disappears.

Solution:

Use studs to secure the water pump effectively.

Use shock absorbers to isolate the vibration. 

2.Sympathetic Vibration

Reason:

The vibration frequency of the pump running is close to the natural frequency of the pipeline or foundation.

Manifestation:

The water pump is rigidly connected to the outside.

Vibration phenomena can increase rapidly over time.

How to Judge:

Hold the water pump and the vibration phenomenon is weakened.

Solution:

Add suitable shock absorbers to the water pump.

Insert a suitable soft connection into the pipeline.

3.Dynamic Balance Drop

Reason:

When the impeller is damaged or the bearings fail, the dynamic balance declines.

Manifestation:

Visible shake of the water pump.

How to Judge:

Hold the water pump and the vibration does not reduced.

The sense of vibration diverges along the radial direction and less in the axial direction.

Solution:

Replace the impeller or bearings.

Measure the shaft runout or dynamic balance if necessary.

4.Shaft Bending

Reason:

During the maintenance of the water pump, the external force causes the shaft bending.

Manifestation:

Visible shake of the water pump.

How to Judge:

Holding the water pump tightly does not reduce the vibration.

The sense of vibration diverges along the radial direction and less in the axial direction.

Solution:

Replace the rotor shaft.

5.Surge

Reason:

There is air at the high level of the inlet line and cannot be exhausted.

There is a hump in the QH curve of the water pump (generally not)

Manifestation:

The water pump vibrates regularly, accompanied by noise changes.

How to Judge:

After adjusting the valve opening, the vibration is abnormally weakened.

Solution:

Adjust the inlet pipeline to cancel the local high point

Replace the water pump

6.Turbulence

Reason:

Affected by the inlet pipeline, it is more common when the pump inlet is too close to the elbow, and the water flow state is chaotic.

Manifestation:

The water pump vibrates obviously, but there is no cavitation noise.

How to Judge:

When the outlet valve is opened larger, the vibration is intensified.

When the valve is reduced, the vibration is reduced.

Solution:

Extend the distance between the pump inlet and the elbow by at least 3 times the length of the pipe diameter.

Welded axial partition inside the elbow.

Next time we will talk about the abnormal performance which is the mostly commonly cases for the end users. Stay tuned and I will keep posted.