Butterfly valves can be used for throttling under ____________ and ___________ conditions.

• A. High-flow, high-pressure
• B. Low-flow, low-pressure
• C. Moderate-flow, high-pressure
• D. Low-flow, high-pressure

Answer: (B)

Butterfly valves are best suited for throttling when the system operates at low flow and low pressure. In those conditions, the disc can be positioned to modulate flow with more predictable changes, while the resulting pressure drop remains modest and wear on the seat and packing stays limited. As flow or pressure increases, throttling becomes less precise and more stressful on the valve—larger pressure drops, higher torque to hold a given opening, potential for noise and wear, and less stable control. For high-flow or high-pressure throttling, other valve types like globe valves provide finer, more linear control. So the ability to throttle effectively is greatest under low-flow, low-pressure conditions.