Centrifugal pump failures result from fluid issues like cavitation (bubble collapse) and dry running (no liquid), operational problems such as misalignment or running the pump too far from its best operating point, mechanical faults including worn or damaged seals and bearings, and incorrect installation or fluid properties like corrosive chemicals. Other factors include clogged lines or impellers, improper impeller rotation, and a lack of routine maintenance. 
Fluid-Related Issues

• Cavitation:
  Vapor bubbles form and collapse in the pump, damaging internal surfaces. This happens when suction pressure is too low. 
• Dry Running:
  The pump operates without liquid or with inadequate fluid, leading to overheating and friction damage to components. 
• Fluid Contamination:
  Abrasive solids or corrosive chemicals in the fluid can wear down impellers and seals. 
• Incorrect Viscosity:
  Pumping higher viscosity fluids than the pump was designed for can increase stress and lead to shaft breakage. 

Operational & Installation Flaws

• Misalignment:
  Improper alignment between the pump and its driver (motor) causes excessive vibration, damaging bearings and the shaft. 
• Improper Operating Conditions:
  Running the pump far from its optimal duty point, using the wrong speed, or starting with an empty suction line can cause damage. 
• Wrong Impeller Rotation:
  Incorrectly wired motors can cause the impeller to rotate backward, which can damage pump components. 
• Poor Installation:
  Pipe strain, excessive belt tension, or incorrect installation can put undue stress on the pump's bearings and shaft. 

Mechanical & Equipment Failures

• Worn Seals:
  Mechanical seals wear out, leading to leaks and potential contamination of the pumped fluid. 
• Worn Bearings:
  Bearings fail due to excessive heat, poor lubrication, or stress from misalignment or impeller imbalance. 
• Damaged Impeller:
  Debris can clog the impeller, or the vanes can become bent, worn, or out of plane. 
• Imbalance:
  An unbalanced impeller, whether new or after modifications, causes vibration and reduces the life of bearings and seals. 

Maintenance & Other Factors

• Lack of Routine Maintenance:
  Skipping lubrication, seal replacement, or cleaning allows minor issues to develop into major failures. 
• Design or Application Mismatch:
  Using a pump that is not suited for the specific application can lead to inefficiencies and breakdowns. 
• Ignoring Warning Signs:
  Unusual noises, excessive heat, or a sudden drop in flow are clear alerts that should be addressed to prevent total failure.