Four Common Causes of Vibration in Double-Suction Pumps During Operation

Vibration in double-suction pumps during operation not only affects equipment stability but may also lead to decreased flow and head, and even damage pipelines and bearings. Understanding the causes of vibration and addressing them promptly is key to ensuring long-term efficient operation of double-suction pumps.

Today, we will explain in detail the four common causes of vibration in double-suction pumps during operation, along with corresponding solutions.

1. Cavitation: Internal Impact Caused by Low Inlet Pressure

Cause Analysis:
When the pump inlet pressure is too low, the liquid inside vaporizes and generates a large number of bubbles. These bubbles travel with the liquid into the high-pressure zone and rapidly collapse, producing strong shock waves that continuously impact the impeller and flow channel surfaces, thereby causing pump vibration accompanied by noticeable abnormal noise.

Solution:
Adjust the outlet gate valve to control the discharge flow, allowing the pump to operate smoothly within its specified performance range, thereby effectively reducing or eliminating cavitation.

2. Impeller Imbalance: Periodic Vibration Caused by Dynamic Balance Failure

Cause Analysis:
If the impeller's dynamic balance is not properly achieved, it will produce a periodic vibration with each rotation. This vibration transmits throughout the pump and piping system, while also causing instability in flow and head, affecting the pump's output and efficiency.

Solution:
Shut down the pump, remove the pump casing top cover, take out the impeller, and send it to a professional maintenance unit for dynamic balance correction. Reinstall the impeller after correction is complete.

3. Pump Shaft and Motor Shaft Misalignment: Vibration and Wear Caused by Misalignment

Cause Analysis:
When the centerlines of the pump shaft and motor shaft are not aligned on the same straight line, additional alternating forces are generated during operation. This not only causes pump vibration but also leads to rapid wear of the coupling's elastic elements, and in severe cases, may damage bearings and mechanical seals.

Solution:
Loosen the coupling, use a dial gauge or laser alignment tool to re-correct the concentricity of the two shafts. Ensure the alignment accuracy meets technical requirements before tightening the coupling.

4. Loose Anchor Bolts: Low-Frequency, High-Amplitude Vibration Caused by Unstable Foundation

Cause Analysis:
When a high-flow double-suction pump is in operation, if the anchor bolts are not tightened properly or become loose after long-term operation, the pump body will shift and shake relative to the foundation, producing low-frequency, high-amplitude vibration. This type of vibration is highly harmful and may, in severe cases, crack the inlet and outlet pipelines or damage the pump feet.

Solution:
Regularly check the tightening status of all anchor bolts. Tighten them promptly if looseness is found. For applications with significant vibration, it is recommended to use anti-loosening washers or schedule regular tightening inspections.

Conclusion

Vibration in double-suction pumps during operation is not something to fear. The key is to identify the cause correctly and apply the right solution:

• Cavitation → Adjust the outlet gate valve

• Impeller imbalance → Correct dynamic balance

• Shaft misalignment → Re-correct concentricity

• Loose anchor bolts → Regularly inspect and tighten

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