Anti-asphyxia and back flow prevention valve between mask elbow and frame

摘要

A respiratory mask assembly includes a frame and an elbow 16 provided to the frame. The inlet 74 of the elbow receives breathing gas supplied under positive pressure for breathing by the patient. A valve 34 is provided between the elbow and the frame and is configured to allow breathing of ambient air and to prevent back flow of gas to the inlet conduit of the elbow in the event that the pressurised breathing gas cannot be supplied to the inlet of the elbow.