Gas flow-sensor for chemical oxygen generation device

Claim 1

A chemical oxygen generation system comprising at least one chemical oxygen generation element, a feed conduit having one end connected to said at least one oxygen reservoir, said chemical oxygen generation element burning to generate oxygen and delivering it to said feed conduit, a permanently open flow restricting orifice connected to said feed conduit downstream of the oxygen generation element, said orifice having a fixed size for permitting flow therethrough at all times and causing a back pressure in said conduit during flow of oxygen, a pressure switch connected to said feed conduit between said oxygen generation element and said orifice, said orifice having a size for producing a back pressure sufficient to maintain said pressure switch in its open position at a flow which is at least a predetermined minimum magnitude of a flow rate of said oxygen flowing through said feed conduit and to close and maintain said pressure switch in its closed position at a flow rate less than said predetermined minimum magnitude, means to which said switch is connected for producing a signal in response to closing of said switch which is indicative of the reduction of the flow rate below said predetermined minimum magnitude, and a normally closed bypass valve connected across said orifice and responsive to a pressure of oxygen within said feed conduit exceeding a predetermined magnitude for being automatically opened.