Smooth centrifugal pump performance is the goal of every operation.
But on occasion, centrifugal pumps can develop issues. This can lead to costly downtimes from repairs or replacement if left unchecked. Therefore, it’s important to monitor your pumps closely so you can catch a problem before it becomes serious.
One of the clearest signs of a problem somewhere in the pump system is vibration. The key to resolving these issues is to determine if they are mechanical or hydraulic in nature.
Here are some typical ways vibration occurs and what you can do to minimize their hazards.
Mechanical Causes
One of the most common causes of mechanical vibrations are when components are out of balance or misaligned in some way.
For example, an unbalanced impeller, motor, or pump shaft will vibrate noticeably. During normal operations, a loose or uneven baseplate, or if the feet of the pump aren’t properly bolted down (a soft foot situation), will also lead to vibration
symptoms in the system.
Another cause could be the parallel or angular misalignment of the couplings between the pump and the motor shafts.
Fortunately, most of these occurrences can be easily found through visual inspection or measuring,
and you can make the adjustments accordingly. If the pump system and all components are balanced and functioning normally but vibrations persist, then the cause may be hydraulic.
Hydraulic Causes
If you suspect hydraulic vibration, the first thing you should look for is cavitation.
This occurs when the vapor pressure is higher than the liquid pressure, which causes small vapor bubbles to develop in the liquid. As they collapse, they form a shockwave effect which can severely damage the pump over time. Noise and vibration are
the most common signs of this condition.
Hydraulic vibrations will also occur if the pump is running way off the Best Efficiency Point (BEP), so that’s another factor to check.
If you can visually see the vibration as the pump operates, that indicates a serious problem you must resolve immediately. In other cases, you need instruments such as vibration mics and sensors to get accurate measurements of the severity.
Critical Components That are Vulnerable to Vibration
While vibration in general is a sign of a problem somewhere, there are certain parts of your centrifugal pump that are especially susceptible to further damage if the pump is allowed to operate without correct adjustments.
Keep a close eye on these parts to prevent extensive malfunctions:
- Pump bearings – Long-term bearing wear will lead to failure over time, but this process speeds up if vibration persists.
- Mechanical seals – With constant vibration, the seals will not perform correctly, and will become more vulnerable to cracking and leaking.
- Couplings – If the vibration is mechanical due to misalignment, the shaft couplings will suffer damage if allowed to run.
There are several possibilities for what causes pumps to vibrate, but by monitoring these crucial mechanical and hydraulic components, you can reduce the effects of vibrations in the pump or stop it before it starts.
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