19/12/2025
What is Cavitation❓
👉 Cavitation is a phenomenon where v***r bubbles form in a liquid due to localized low pressure, typically at the eye (inlet) of the impeller in a centrifugal pump. When these v***r bubbles travel to higher-pressure zones within the pump, they collapse violently, creating powerful shockwaves.
These micro-explosions may sound minor, but they can erode metal surfaces, damage impellers, and reduce efficiency dramatically over time.
👉How Cavitation Occurs in Centrifugal Pumps
The most common cause of cavitation is when the pressure in the suction side of the pump drops below the liquid's v***r pressure, causing v***rization. Several factors can contribute:
🟠 Low Net Positive Suction Head (NPSH) available
🟢 High fluid temperature
🟣 Excessive suction lift
🟤 Long or narrow suction piping
🟡 Blocked or clogged filters or strainers
🔵 High impeller speed (RPM)
👉Types of Cavitation in Pumps
1️⃣ Suction Cavitation
Occurs when pump suction pressure is too low. V***r bubbles form at the eye of the impeller and collapse as they move toward higher pressure zones.
2️⃣ Discharge Cavitation
Happens when there’s a restriction in the pump discharge—like a partially closed valve—causing pressure to rise quickly. This forces liquid to recirculate inside the pump, leading to v***r formation and bubble collapse.
3️⃣ Vane Passing Cavitation
Occurs near impeller vanes, where pressure fluctuations due to design geometry can cause localized bubble formation and collapse.
4️⃣ Internal Recirculation Cavitation
Caused by low flow rates, leading to recirculation within the pump and resulting in high-velocity zones that cause cavitation.
👉 Effects of Cavitation
◾ Pitting and erosion of impeller and volute surfaces
◾ Vibration and noise (often described as gravel or marbles inside the pump)
◾ Reduced pump efficiency
◾ Increased power consumption
◾ Seal and bearing failure
◾ Complete pump breakdown, if unaddressed
👉 Detecting Cavitation
Operators can identify cavitation through several signs:
▪️ Unusual noise (like rattling or grinding)
▪️ Drop in flow rate or head
▪️ Visible damage on impeller surfaces
▪️ Fluctuating pressure readings
▪️ Vibration in pump casing or pipework
👉 Preventing Cavitation
✅ Ensure adequate NPSH (Net Positive Suction Head)
▪️ Compare NPSH available with NPSH required (NPSHa > NPSHr)
▪️ Use larger diameter suction lines
▪️ Reduce pipe friction losses
✅ Lower the fluid temperature
▪️ Cooler fluids reduce v***r pressure, making cavitation less likely.
✅ Reduce pump speed (RPM)
▪️ Slower impeller speed lowers the risk of v***r formation.
✅ Use a booster pump
▪️ It can help maintain adequate suction pressure.
✅ Keep suction piping clean and short
▪️ Avoid unnecessary bends, valves, or restrictions.
✅ Install inducer impellers or anti-cavitation devices
These are designed to handle low-pressure conditions more effectively.
