Abstract: A gas cylinder dispensing valve having an internal flow path provided with a pressure regulator. An isolation valve is provided within the flow path between the pressure regulator and a gas inlet of the valve and a flow control valve is provided within the flow path between the pressure regulator and a gas outlet to discharge the gas. Both isolation valve and the flow control valve can be manipulated by a single control knob which when set in an off position closes the isolation valve. The control knob can be rotated from the off position to select discrete, calibrated flow rates or an auxiliary position in which gas may be dispensed at a regulated pressure from an auxiliary outlet port.