A gate valve is designed to remain fully open or fully closed. Which statement best describes its use?

• A. Throttle for precision control
• B. Be decorative
• C. Used only after installation
• D. Remain open all the way or closed all the way

Answer: (D)

Gate valves are built for on/off service rather than fine flow control. They use a gate that slides into a seat to seal, so when fully opened the passage is wide with minimal obstruction, and when fully closed it provides a tight seal. Partially opening a gate valve creates turbulence, wear on the gate and seats, and a large, unreliable pressure drop, making it unsuitable for precise throttling. That’s why the best description is that it remains either fully open or fully closed. Other options don’t fit: throttling is better done with valves designed for control, such as globe valves; decor is not a function of a valve; valves aren’t only used after installation but as a regular part of the piping system.