Which device in a hydraulic system allows circulation of fluid when there are no demands on the system?

In hydraulic systems, the device that allows for the circulation of fluid when there are no demands on the system is the accumulator. An accumulator stores hydraulic fluid under pressure and can release it when needed, even if there is no immediate demand placed on the system.

When the hydraulic system is at rest, the accumulator maintains a reserve of fluid, ensuring that there is an available supply for immediate needs when system demands increase. This function helps to maintain system pressure and improve responsiveness during operation. The accumulator can also help absorb shocks and pulsations in the system, contributing to smoother performance.

While a pressure regulator manages the pressure within the system to ensure it remains at the desired level, it does not facilitate circulation in the same way that an accumulator does. Control valves direct the flow of fluid to various components, but they do not maintain circulation on their own. Flow meters are used to measure the rate of flow within the system rather than to control or store fluid. Therefore, the accumulator is the ideal device for allowing fluid circulation when demand is low.