GB828362A - Improvements in or relating to oxygen breathing apparatus - Google Patents

Abstract

828,362. Respiratory appliances. KIDDE CO. Ltd., W. June 9, 1958 [April 4, 1957], No. 10998/57. Class 81 (2). Oxygen breathing apparatus for aircraft, in which masks are automatically presented to passengers when the cabin pressure falls below a predetermined minimum, has means for admitting oxygen under pressure to a supply line, under predetermined pressure conditions, and pressure-actuated latch means for releasing masks from a storage locker. In the complete installation the supply line 5, Fig. 1, has a number of points 6, to which mask presentation units 7 or individual masks 8 may be connected, and has a first storage cylinder 1 connected through a pressure sensitive valve 9 and reducing valve 10 so that when the cabin pressure falls to a predetermined minimum the valve 9 opens automatically and gas is admitted to the lines 5 and 15. The internal pressure closes a vent valve 14 and opens a valve 17, Fig. 2, which admits it to a manifold 16 and thence to the mask hoses 25. In addition it releases a latch 20 through an aneroid control device 19 so that the door 21 of the locker opens and the masks drop downwards. At this stage, however, no gas passes to the masks since in each hose a telescopic valve 26 is held closed by the clip 33, in which it is retained, but as soon as a passenger pulls the mask downwards towards himself, this valve body is pulled clear of its clip and its ends move apart, under the action of an internal spring, and the valve is opened, so passing gas to the mask. A secondary gas cylinder 2, Fig. 1, is also connected to the supply main 5 through a manual stop valve 11 and reducing valve 12, which is set to a lower pressure than the valve 10. After the system has come into operation the stop valve 11 is opened and, after cylinder 1 is exhausted and the supply pressure has fallen sufficiently for valve 12 to be operative, the supply is continued from cylinder 2. The system may also be supplied from a cylinder 3 through a reducing valve 41 set to a relatively low pressure and this is used when only one or a few passengers require oxygen under normal flight conditions. This supplies oxygen at a pressure sufficient to close the vent valve 14 but too low to release the locker catches and, under these circumstances, a mask 8 is fitted into an appropriate union 6 for the passenger concerned.