Which valves only require a 90 degree turn of the stem to go from fully opened to fully closed?

• A. Plug valve, ball valve, and butterfly valve
• B. Gate valve and globe valve
• C. Check valve and relief valve
• D. Needle valve and globe valve

Answer: (A)

Understanding quarter-turn valve operation is being tested. Valves in this group control flow by rotating a cylindrical element—such as a plug, a ball, or a disc—around its axis. When the element’s bore or port aligns with the pipeline, fluid flows freely; a simple 90-degree turn rotates the element to block the flow, giving a quick open-to-closed change. This makes plug valves, ball valves, and butterfly valves ideal for fast, decisive on/off control with minimal handle movement.

Other valves, like gate and globe valves, require the stem to move linearly to lift or lower a gate or disk. That means multiple turns are needed to transition from fully open to fully closed, making them multi-turn valves. Needle valves also need several turns for fine adjustment. Check valves and relief valves aren’t operated by turning a stem to open or close in the same way; check valves are typically automatic to prevent backflow, and relief valves are pressure-activated safety devices.