Which statement about a valve control system is true according to the given definitions?

• A. DCS is used to monitor valve position directly
• B. DVC is attached to the valve actuator controls and monitors the valve position
• C. OL stands for Overload
• D. Proximity sensors are used to measure pressure directly

Answer: (B)

Valve position feedback is what makes a valve control loop work. A digital valve controller (DVC) is mounted on the valve actuator and reads the actual valve position, sending that information back to the control system so the commanded position can be reached accurately. This creates a true closed-loop control, where the controller continuously compares the desired position with the actual position and adjusts the actuator to minimize any difference.

DCS handles broader process control and monitoring, but it isn’t the device that directly provides local valve-position feedback through the actuator. Proximity sensors measure the presence or absence of nearby objects, not fluid pressure, so they aren’t used to measure pressure directly. The other statements don’t describe the valve-position feedback arrangement in the way that the DVC attached to the actuator does.