A valve is provided for controlling the flow of gas through an anesthesia or respiratory breathing circuit. The valve includes a valve body having a first port, a second port, and a third port. The third port includes a flow restrictor for restricting the flow of gas through the third port. A valve closing member is provided that is moveable between an open position where gas can flow through the third port, and a closed position. In the closed position, gas is prevented from flowing through the third port.
