Automatic safety valve for respiratory equipment which is counter-balanced and self-adjusting

Apparatus for delivering pressurized gas to the airway of a patient, said apparatus comprising:

• gas flow generator means for providing a flow of said pressurized gas;
• conduit means for delivering said gas flow to the airway of said patient;
• a means for interfacing with a patient having an inlet;
• and
• a self-regulating valve device comprising:
• a housing including a primary inlet adapted for connection to said conduit means, a secondary inlet in communication with an ambient atmosphere, and an outlet adapted for connection to said patient interface means inlet;
• and
• a substantially rigid valve element and means for pivotally mounting said valve element within said housing, said valve element being operable to open said primary inlet and close said secondary inlet in the presence of a flow of pressurized gas from said gas flow generator means and to open said secondary inlet and close said primary inlet in the absence of said flow of pressurized gas, said valve element comprising a closure portion dimensioned to cover said primary and secondary inlets and means for counterbalancing said closure portion with respect to said pivotally mounting means.