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[abo annas]

Hi to all,
What are the vibration causes for the ceterifugal pumps? is the total flow through the the pump one of them? i.e if we decrease the flow through the pump the vibration will decrease..
all coments from all experienced people are wellcome.
thanks and regards.

[WMJ]

Dear annas,

The vibration can be because any of the following reason:

1. Mechanical causes

• A bent or warped shaft
• The mass of the pump base is too small
• Unbalanced rotating components. Damaged impellers and non concentric shaft sleeves are common.
• Pump and driver misalignment.
• Pipe strain. Either by design or as a result of thermal growth.
• Thermal growth of various components, especially shafts.
• Rubbing parts.
• Worn or loose bearings.
• Loose hold down bolts.
• Loose parts.
• Product attaching to a rotating component.
• Damaged parts.

2. Hydraulic causes

• Operating off of the pump's best efficiency point
• Turbulence in the system (non-laminar flow)
• Water hammer.
• Vaporization of the product
• Impeller vane running too close to the pump cutwater
• Internal recirculation.
• Air getting into the system through vortexing etc.

3. Other causes

• Harmonic vibration from nearby equipment
• Operating the pump at a critical speed. Watch out for this problem in variable speed and pulley driven pumps
• Seal "slip stick" at the seal faces. This can occur if you are pumping a non-lubricating fluid, a gas or a dry solid
• A pump discharge recirculation line aimed at the seal faces