A breathing valve for use in association with breathing devices for the administration of gases to a patient, and comprising:
- a valve chamber having an upstream end connectable to a supply of gas, and having a downstream end connectable to a breathing device, there being respective upstream and downstream openings in said chamber, whereby gas can be admitted through said upstream opening, and can be administered through said downstream opening in a first direction to said breathing device;
- a tubular downstream connection member defining said downstream opening, and having upstream and downstream ends;
- valve seating surfaces around said upstream end of said tubular connecting member;
- gas flow passages in said chamber adjacent said upstream end of said tubular connection member whereby exhaled gases may pass from said breathing device through said tubular connection member in a second direction, and may be discharged to atmosphere, and through which atmospheric air may be inducted into said breathing device in a third direction;
- a single integral flow control member extending across said chamber between said upstream and downstream ends, said flow control member in turn comprising:
- a circular gas flow port located along the central axis of said flow control member;
- one-way valve means incorporated in and forming an integral part of said flow control member in registration with said gas flow port whereby gas may flow from said chamber through said gas flow port and said valve means into said tubular connection member, said valve means preventing return flow in the oppositve direction through said valve means;
- a thick, closure ring incorporated in and forming an integral part of said flow control member surrounding and defining said gas flow port and movable into and out of sealing engagement with said valve seating surfaces, whereby said closure ring will prevent communication between said tubular connection member and said gas flow passages upon inhalation of gas from said upstream end of said chamber;
- said closure ring being movable away from said seating surfaces upon exhalation, thereby unsealing the same and allowing gas flow in said second direction through said tubular connection member and out of said gas flow passages;
- peripheral mounting means formed integrally with said flow control member for securing the flow control member to said chamber;
- and,
- an annular pressure responsive thin, flexible diaphragm wall incorporated in and forming an integral part of said flow control member located between said peripheral mounting means and said thick closure ring and formed in section into a generally concave/convex annular fold with the convex profile directed towards said gas flow passages, and responsive to obstruction of gas flow into said chamber from said upstream end, and further responsive to inspiratory effort by a patient through said tubular connection member whereby to respond to the pressure difference created thereby and cause said closure ring to move away from said seating surfaces, thereby permitting inward air flow through said gas flow passages in said third direction into said tubular connection member for inhalation through said breathing device.