Abstract: An on-board oxygen generating system (OBOGS) includes a molecular sieve oxygen generating system (MSOGS), a breathable gas delivery regulator selectively operable to deliver 100 percent MSOGS output gas or air diluted output gas to a user, a back-up storage plenum and control means arranged so that when air diluted delivery gas is selected a portion of 100 percent MSOG output gas is diverted to charge the storage plenum and when 100 percent MSOG output delivery gas is selected diversion to the storage plenum is automatically prevented. The breathable gas delivery regulator includes an injector adapted to induce a flow of air to mix with 100 percent MSOG output gas when air diluted delivery gas is selected.

Abstract: An aircrew life support system has an on-board oxygen generating system (OBOGS) connected for delivering oxygen-enriched product gas to a breathing demand regulator and a plenum storage container. The concentration of oxygen in the product gas is sensed by a gas concentration sensor which supplies signals to an electronic control unit (ECU). The ECU outputs signals for switching a control valve which controls product gas to be delivered to the regulator from either the OBOGS or the storage container. The ECU also outputs signals to a charge valve which is opened to allow product gas from the OBOGS to charge the storage container when product gas enriched with oxygen above a predetermined concentration is being delivered by the OBOGS and there is excess capacity over the demand requirements at the regulator.

Abstract: A flueric partial pressure sensor (10) includes a flueric bridge sensor (10a) having two bridge legs (11, 12) adapted for sensing a reference-gas and a sample-gas. A linear resistor (14, 15) and an orifice resistor (16, 17) are incorporated in each leg and arranged to cause asymmetric flow rates therethrough. Inlets to the two bridge legs are subject to a datum pressure within a datum pressure chamber (38) so that a change of datum pressure automatically changes control signals output by the sensor. The partial pressure sensor is disclosed in combination with a molecular sieve type gas concentration system (24) in an on-board oxygen enrichment of air system for an aircraft and enables the oxygen concentration in oxygen enriched air delivered by the system to be appropriate to breathing requirement at an altitude intermediate aircraft cabin and ambient atmospheric pressures.