What is the primary function of a valve?

• A. Moves fluids or gases.
• B. Is rarely used in a nuclear power plant.
• C. Controls flow.
• D. Is always welded into a system.

Answer: (C)

Valves regulate how much, where, and when fluid or gas flows through a system by opening, closing, or throttling the passage. Their main job is to control flow: they can fully open to allow maximum flow, close to stop it, or partially open to throttle the rate as needed. This control is essential for maintaining proper pressures, directing flow to different parts of a plant, and ensuring safe, reliable operation.

Saying that valves move fluids describes what another device like a pump does; a valve itself doesn’t propel fluid, it controls its passage. The idea that valves are rarely used in a nuclear power plant is incorrect; valves are critical components throughout such facilities. And they aren’t always welded into a system—many valves are connected by flanges or threaded joints, with welding used in some configurations but not universal.