A relief valve in a hydraulic system is primarily used for?

A relief valve in a hydraulic system plays a critical role in maintaining the pressure within safe operating limits. Its primary function is to prevent excess pressure from building up, which can lead to system failure or damage to components. When the pressure in the hydraulic circuit exceeds a predetermined level, the relief valve opens, allowing a portion of the hydraulic fluid to escape back to the reservoir or another designated area. This action effectively regulates the pressure, ensuring that it remains within a safe range for the hydraulic components to function properly.

The other choices, while related to hydraulic systems, do not reflect the primary purpose of a relief valve. Flow measurement pertains to assessing the amount of fluid passing through the system, direction control refers to the ability to direct fluid flow within the system, and fluid filtration involves removing contaminants from the hydraulic fluid. Each of these functions is important in its own right, but they do not encompass the core function of pressure control that a relief valve serves.