Which valve is typically used for on/off service with minimal leakage and high reliability and requires turning a wheel to move the gate into the flow path?

• A. Diaphragm valve
• B. Gate valve
• C. Ball valve
• D. Butterfly valve

Answer: (B)

Gate valves are built for solid isolation. They use a flat gate that moves straight into or out of the flow path when you turn the stem, typically with a handwheel. As you tighten the wheel, the gate slides against the seats, creating a tight seal that minimizes leakage when fully closed. The linear motion and robust construction give high reliability for on/off service, which is why they’re commonly chosen in wastewater systems where dependable shutoff is essential. Other valves—diaphragm, ball, and butterfly—operate by different mechanisms (diaphragm seals with a flexible membrane, a rotating ball, or a rotating disk) and don’t use a gate that moves into the flow path with a wheel-driven stem, so they don’t match the described combination of gate-like shutoff and wheel-controlled linear motion.