Abstract: An emergency breathing system has an anti-suffocation valve located in a housing between a source of breathable fluid and a distribution mask. The housing has a chamber which is connected to the distribution mask and an opening which connects the chamber with the surrounding environment. The anti-suffocation valve responds to an inhalation demand of a recipient to allow air from the surrounding environment to enter the chamber and satisfy the inhalation demand of a recipient to allow air from the surrounding environment to enter the chamber and satisfy the inhalation demand. A hydrophobic filter surrounds the opening and prevents the entry of any water present in the surrounding environment into the chamber which could inhibit cyclic inhalation of breathable fluid by the recipient.

Abstract: An adjustable check valve for use in an oxygen regulator to establish limits at which a resiliently biased disc moves away from a seat to allow air to enter an atmospheric chamber. A regulator is connected to a linkage which operates an air flow valve and an oxygen proportioning flow valve. The regulator is responsive to inlet oxygen pressure such that a change in altitude causes a corresponding change in flow relationship of air through the air valve and oxygen through the oxygen valve.

Abstract: A breathing system control valve having a housing with a distribution chamber therein which communicates with a source of air under pressure. A shaft which extends into the distribution chamber engages a plurality of discs and is operatively connected to a motor which provides the shaft with a rotative torque to alternately communicate air under pressure through a portion of the discs to either a first chamber or a second chamber wherein an oxygen enriched product effluent is developed while another portion of the discs allows a purge fluid from the other of the first and second chambers to escape to the atmosphere. Prior to the transfer of the air under pressure from one of the first and second chambers to the other, an equalization passage is opened to permit communication therebetween to establish a rapid operational build-up of air under pressure.