Which valve is designed to regulate flow instead of shutting it off?

• A. Throttle valve
• B. Block valve
• C. Check valve
• D. Relief valve

Answer: (A)

Regulating flow means adjusting how much fluid can pass through while keeping the flow moving. The throttle valve is designed for this purpose, offering an adjustable restriction that you can open or close to set the desired flow rate. It stays partially open to modulate flow, rather than shutting it off entirely. In contrast, a block valve is used to stop flow by fully closing the passage, a check valve allows flow in one direction but doesn’t set a rate, and a relief valve opens at a set pressure to vent excess pressure rather than control the normal flow rate. So for controlling how much fluid moves through the system, the throttle valve is the best fit.