Abstract: An apparatus for supplying a breathing gas to a patient has a gas supply for generating a flow of breathable gas during an inspiration and an expiration phase of a patient breathing cycle. An inspiration line is provided having an inlet through which a flow of breathing gas from the supply can pass as well as an expiration line through which an expiration gas from the patient can flow. A flow controller is provided for selecting, during an inspiration phase, a first flow path for gas from the supply into the inlet and for selecting, during the expiration phase, a second flow path for gas from the supply in a direction across a venturi outlet of the expiration line, to enhance removal of expiration gas therefrom by venturi suction.

Abstract: A fluid pressure relief valve has an aperture for the flow through of a fluid, the aperture being disposed between a fluid inlet and a fluid outlet. A movably mounted valve element is disposed for pressure communication with the fluid and is movable to unseal the aperture when an opening force exerted by the communicated fluid pressure on the valve element exceeds a counteracting threshold force. A biasing source provides a bias force for moving the valve element toward sealing the aperture. The valve element is disposed for pressure communication with the fluid such that a closing force less than and counter to the opening force is additionally exerted on the valve element by the communicated fluid pressure. This force in combination with the bias force generates the threshold force.