To operate a two-position solenoid-operated DCV, what is required to initiate operation?

• A. A current flow
• B. Air pressure
• C. A mechanical handwheel
• D. Manual reset

Answer: (A)

The key idea is that the actuation of a two-position solenoid-operated DCV starts with energizing the solenoid coil. When electrical current flows through the coil, it creates a magnetic field that pulls the valve spool into a new position, changing the air pathways and initiating the valve’s operation. Once the current stops, a return mechanism (usually a spring) pushes the spool back to its original position, ready for the next cycle.

Air pressure alone doesn’t initiate the actuation in this setup, and a handwheel or manual reset is only for manual control or holding a state in some designs, not the basic actuation. Continuous current isn’t required for the basic start in all designs (there are latching types), but for a standard two-position solenoid valve, applying current is what begins operation.