A combined dirt collector and cutout cock (CDC & COC) device for a rail car control to prevent unintentional re-pressurization of the control valve and rail car braking system. The device has an inlet configured for interconnection to an air supply, an outlet configured for interconnection to a control valve of a rail car, a valve moveable between a first position where an inlet is connected to an outlet and a second position where the inlet is isolated from the outlet, and a control valve vent positioned downstream of the valve and configured to open in response to the valve being moved into the second position. The valve may include a ball having a first passageway for selectively connecting and disconnecting the inlet from the outlet and a second passageway formed therethrough that is positioned to interconnect the outlet with the vent when the valve is in the second position.