Engineering Utilities 2 – Mechanical Practice Exam 2025 - Free Mechanical Engineering Practice Questions and Study Guide

Cavitation primarily causes damage to the impeller and casing of a pump due to the formation and collapse of vapor bubbles in the liquid being pumped. When the pressure in the pump falls below the vapor pressure of the liquid, vapor bubbles form. As these bubbles travel to regions of higher pressure in the pump, they collapse violently. This collapse can generate shock waves and microjets that impact the surfaces of the impeller and casing.

The resulting damage manifests as pitting or erosion on the surfaces, particularly on high-velocity areas like the edges of the impeller blades and along the casing where the flow is most turbulent. Over time, this erosion can lead to reduced pump efficiency, increased vibration, and ultimately pump failure.

In contrast, while the motor and drive system, sealing mechanisms, and fluid intake screen may be affected by other issues within the pump operation, they are not the primary components subject to damage specifically caused by cavitation. The direct impact of vapor bubble collapse is localized to the impeller and casing, making them the most vulnerable components in this scenario.