Cavitation: How Tiny Bubbles Destroy Pumps

Tiny vapor cavities can pit metal, shake a pump, and gradually destroy an impeller. This visual engineering guide explains how cavitation begins, why cavities collapse, how the damage accumulates, and how NPSH helps engineers prevent it. Inside a centrifugal pump, local pressure can fall below the liquid's vapor pressure near the impeller eye. Vapor cavities form, move into a higher-pressure region, and collapse. Repeated microjets and pressure pulses can erode the metal, while the pump may develop gravel-like noise, vibration, unstable performance, and increased mechanical loads. In this video: Why water can form vapor below 100 °C Why cavitation is different from air entering the suction line Where cavitation starts in a centrifugal pump How cavity collapse creates cumulative pitting What NPSH-A and NPSH-R mean Practical ways to reduce cavitation risk Chapters: 00:00 What cavitation damage sounds like 00:41 Water can boil without being hot 01:05 Vapor cavities vs. air bubbles 01:33 Where cavitation starts 02:24 Why vapor cavities collapse 02:49 How collapse damages metal 03:18 From pitting to reliability problems 03:36 Symptoms and diagnosis 04:24 NPSH explained 05:00 Preventing pump cavitation 05:51 The complete cavitation chain 06:34 Technical references Technical references: 1. U.S. Department of Energy — DOE Fundamentals Handbook: Thermodynamics, Heat Transfer, and Fluid Flow, Volume 3 of 3, pp. 48–49 https://www.energy.gov/sites/default/... 2. U.S. Department of Energy — Improving Pumping System Performance: A Sourcebook for Industry, Second Edition, pp. 20–21 and NPSH section https://www1.eere.energy.gov/manufact... 3. P. V. Rao and D. H. Buckley — Empirical Relations for Cavitation and Liquid Impingement Erosion Processes, NASA-TP-2339 https://ntrs.nasa.gov/citations/19840... 4. B. C. S. Rao and D. H. Buckley — Characterization of Erosion of Metallic Materials Under Cavitation Attack in a Mineral Oil, NASA-TM-86934 https://ntrs.nasa.gov/citations/19850... These references support the technical discussion and do not imply endorsement by NASA or the U.S. Department of Energy. Visualizations are original conceptual illustrations, not calibrated CFD results. See the forces. Understand the machine. Subscribe to MechFlow Lab for visual engineering explanations about fluid mechanics, pumps, mechanisms, and machine design. #Cavitation #CentrifugalPumps #MechanicalEngineering