Anti-suffocation means for aircraft breathing mask

Anti-suffocation means for allowing the communication of air from a surrounding environment into a breathing system in an emergency condition when a source of breathable fluid is insufficient to meet an inhalation demand of a recipient, said anti-suffocation means comprising:

• a housing having a bore therein adapted to be connected to said breathing system, said housing having an opening connecting said bore to the surrounding environment;
• valve means responsive to said inhalation demand for allowing communication of air through said opening;
• filter means connected to said opening, said filter having a microporous membrane means for forming a barrier through which the transmission of water is inhibited to prevent contamination of the breathing system by any water present in the surrounding environment during the operation of said valve means by said inhalation demand;
• clip means attached to said housing for sealing said opening from the surrounding environment prior to said emergency condition;
• and
• means for removing said clip means from the housing when an emergency condition occurs to allow said anti-suffocation means to operate should the recipient present a predetermined inhalation demand on said breathing system.