What is any device used to control fluids in a closed system called?

A device used to control fluids in a closed system is known as a valve. Valves are crucial components within fluid systems as they manage the flow and pressure of liquids or gases. By opening, closing, or partially obstructing passageways, valves can regulate the direction and rate of fluid movement. This functionality is essential in various applications, including gas turbine systems, where precise control of fuel and air flow can significantly impact performance and efficiency.

Pumps, on the other hand, are responsible for moving fluids from one location to another rather than controlling the flow or pressure. Filters serve to remove impurities from fluids, ensuring cleanliness and protecting system components, while actuators are mechanisms that convert control signals into physical motion, often operating valves but not functioning independently as fluid control devices.