A diaphragm-type control valve having a diaphragm and a valve body is provided preferably for use in the separation of and fluid control between a fluid source and a pressurized gas volume. The diaphragm element and a port in the body together form an intermediate chamber that eliminates the need for a check-valve downstream of the valve. In one preferred embodiment, an inner surface of the valve body defines a chamber having an inlet and an outlet in communication with the chamber, and an elongated seat member defining a groove in communication with the port. A diaphragm member having upper and lower surfaces is disposed within the chamber. The lower surface preferably includes a pair of spaced apart elongated members defining a channel therebetween. The diaphragm member engages the seat member placing the channel in communication with the groove to define an air seat in communication with the port.