In a system using a pressure-compensated flow control valve, what is maintained constant when both upstream and downstream pressures rise?

• A. Temperature
• B. Flow rate
• C. Viscosity
• D. Pressure

Answer: (B)

A pressure-compensated flow control valve is built to keep the output flow nearly constant even as supply and load pressures change. It uses a compensating mechanism that senses downstream pressure and adjusts the throttling opening so the flow rate stays at the set value. When both upstream and downstream pressures rise, the valve adapts its opening to prevent the flow from increasing, maintaining a steady flow through the system. Temperature and viscosity can affect how easily fluid moves, but they aren’t what the valve fixes, and the pressure in the system isn’t held constant—the flow rate is.