Which valve has a rotating ball with a channel through which flow can be started or stopped?

Which valve has a rotating ball with a channel through which flow can be started or stopped?

• A. Ball valve
• B. Globe valve
• C. Needle valve
• D. Diaphragm valve

Answer: (A)

This describes a ball valve. It uses a spherical ball with a bore (a through-channel) inside. When the bore lines up with the pipeline, flow starts; rotate the ball a quarter turn and the bore is perpendicular to the flow, stopping it. This quarter-turn mechanism allows quick on/off control and a tight seal when closed. Other valves work differently: a globe valve moves a plug or disk in a linear fashion to throttle flow, not with a rotating ball; a needle valve uses a long, tapered needle for precise, fine control; a diaphragm valve seals with a flexible diaphragm against a seat and has no rotating ball. The rotating-ball design is what uniquely enables the described start/stop flow behavior.

This describes a ball valve. It uses a spherical ball with a bore (a through-channel) inside. When the bore lines up with the pipeline, flow starts; rotate the ball a quarter turn and the bore is perpendicular to the flow, stopping it. This quarter-turn mechanism allows quick on/off control and a tight seal when closed.

Other valves work differently: a globe valve moves a plug or disk in a linear fashion to throttle flow, not with a rotating ball; a needle valve uses a long, tapered needle for precise, fine control; a diaphragm valve seals with a flexible diaphragm against a seat and has no rotating ball. The rotating-ball design is what uniquely enables the described start/stop flow behavior.