A mechanical device that controls flow into, inside of, or out of a piping system is called a:

• A. Blind flange
• B. Pump
• C. Valve
• D. Flow controller

Answer: (C)

Valves are the mechanical components placed in piping to regulate, start/stop, or direct the flow of fluid. They work by moving a part such as a disk, plug, or gate into or out of the flow path, changing the cross-sectional area or sealing the path. This makes them the standard device for flow control in piping systems, whether you need to throttle flow or completely shut it off. A blind flange is simply a plate used to seal a pipe end and does not regulate flow. A pump adds energy to move fluid through the system, not to control flow by obstructing the path. A flow controller is a broader term that can describe devices regulating flow, but the specific mechanical device used to control flow in a piping system is a valve.