The valve is closed on a full and operational cylinder.
The valve operates on the differential pressure principle with two chambers separated by a piston and with different effective areas. The gas contained in the upper chamber applies pressure to the piston and keeps the valve closed. When actuated by a ACTF230 type actuator, the pressure in the upper valve chamber is released, the piston moves up and opens the valve.
Once the valve has been opened, it cannot be closed again, and the cylinder will be fully emptied. The valve will close after complete discharge.