What does cavitation in a hydraulic system refer to?

Cavitation in a hydraulic system refers to the formation of vapor bubbles in the fluid. This phenomenon occurs when the local pressure in the hydraulic fluid drops below the vapor pressure of that fluid, causing it to vaporize momentarily and form bubbles. When these vapor bubbles move into areas of higher pressure within the system, they can collapse violently, potentially leading to significant damage to components like pumps and valves due to the shock waves generated by the collapsing bubbles.

Understanding cavitation is critical for maintaining the efficiency and reliability of hydraulic systems, as it can lead to erosion, noise, vibration, and overall system failure if not properly managed. The other choices do not directly relate to the specific issue of cavitation in a hydraulic context. For instance, although increased fluid temperature, high levels of dissolved gases, and excessive pressure can be important factors in hydraulic systems, they do not define cavitation itself, which is specifically concerned with the vapor phase of the fluid.