How is viscosity characterized in hydraulic fluid?

Viscosity refers to a fluid's internal resistance to flow, making the characterization of viscosity in hydraulic fluid central to understanding its behavior in a hydraulic system. When you think of viscosity, consider it as the thickness or stickiness of the fluid; a higher viscosity means the fluid is thicker and flows more slowly, while a lower viscosity means it is thinner and flows more easily. This internal resistance is crucial because it affects how easily the fluid can be pumped and how it transmits power in the system.

Maintaining the appropriate viscosity is essential for efficient operation, as it influences factors such as the performance of hydraulic components, the leakage rates in seals and valves, and the overall efficiency of the hydraulic system.

Regarding the other choices: while temperature response can affect viscosity, it does not define it. Density compared to water may provide some information about a fluid, but it is not a measure of viscosity. The amount of air dissolved in the fluid is related to its compressibility and potential for cavitation, which are separate properties from viscosity.