How to Reduce Cavitation in Pumps – Causes, Solutions & Best Practices

💧 How to Reduce Cavitation in Pumps – Causes, Solutions & Best Practices

Cavitation is one of the most destructive problems in centrifugal pumps. It occurs when the pressure at the pump suction drops below the liquid’s vapor pressure, forming vapor bubbles that collapse violently in higher‑pressure zones. This collapse produces shock waves that damage the impeller, casing, seals, and bearings, leading to noise, vibration, and reduced efficiency.  

Fortunately, cavitation can be minimized or eliminated by following proper design, operation, and maintenance practices.

🔹 Practical Methods to Reduce Cavitation

1. Increase Suction Pressure

- Provide a positive suction head by placing the suction tank at a higher elevation or using a pressurized tank.  

- Higher suction pressure increases Net Positive Suction Head Available (NPSHa), reducing the risk of cavitation.  

2. Control Fluid Temperature

- If the fluid temperature is close to its vapor pressure, cavitation risk increases.  

- Lowering the fluid temperature reduces vapor pressure, improving NPSHa.  

- This is especially important in hot water circulation systems and chemical processes.  

3. Inspect Suction Line Components

- Regularly check valves, strainers, and suction piping for blockages or fouling.  

- Clogged strainers or partially closed valves increase friction losses, lowering suction pressure.  

- Routine inspection is often the first step in troubleshooting cavitation.  

4. Reduce Impeller Speed

- Lowering impeller speed reduces velocity at the suction side, minimizing pressure drop.  

- Use variable speed drives (VSDs) to adjust pump speed according to system demand.  

- Ensure reduced speed still meets required flow and pressure conditions.  

5. Check for Fouling or Deposits

- If the system previously worked well, cavitation may be due to fouling in suction lines or valves.  

- Cleaning and maintenance can restore proper suction conditions.  

6. Inspect Pump Impeller

- Cavitation can severely damage impeller blades over time.  

- Inspect impellers for erosion, pitting, or cracks.  

- If damage is extensive, consider overhauling or replacing the pump to restore performance.  

🔹 Key Takeaways

- Cavitation occurs when suction pressure falls below vapor pressure, forming bubbles that collapse violently.  

- NPSHa must always be greater than NPSHr to avoid cavitation.  

- Solutions include:  

  - Increasing suction pressure.  

  - Reducing fluid temperature.  

  - Inspecting suction line valves and strainers.  

  - Lowering impeller speed.  

  - Cleaning fouled suction components.  

  - Inspecting and repairing impellers.  

- Preventive maintenance and proper design are the best long‑term strategies.