What type of system is characterized by the fluid being reused repeatedly in hydraulic or pneumatic applications?

A closed system is characterized by the fluid being reused repeatedly in hydraulic or pneumatic applications. In this type of system, the fluid—whether liquid in hydraulic systems or gas in pneumatic systems—remains contained within a circuit, allowing it to circulate without being expelled into the environment. This containment allows for efficient energy transfer and minimizes the need for continuous refilling, which is a crucial advantage in many industrial and mechanical applications.

In contrast, an open system typically allows fluid to enter and exit freely, resulting in it not being reused in the same manner. Pneumatic systems specifically refer to systems that use compressed gas, while vacuum systems deal with the removal of air or other gases to create a vacuum, but both can be either open or closed depending on their design and application. The closed system's efficiency and fluid management make it a fundamental concept in understanding hydraulic and pneumatic systems.