GB1207153A - Improvements in or relating to oxygen breathing supply systems for use in aircraft - Google Patents

Abstract

1,207,153. Respiratory appliances. WALTER KIDDE CO. Ltd. 15 Feb., 1968 [22 March, 1967], No. 13556/67. Heading A5T. Apparatus for regulating the gas supply pressure to a plurality of face masks and operating pressure-responsive latch means to open mask retaining means for releasing the masks for use comprises first and second lines 28, 29 'between an inlet 22 and an outlet, a surge valve 31 in the first line 28 which is opened when ambient pressure falls below a predetermined amount to provide a pressure pulse for opening the latch, a valve 38 closing the first line 28 after a ,short period to terminate the pressure pulse and a main supply valve 45 in the second line 29. Gas entering the device is controlled by a pressure reducing valve 24. The surge valve, which comprises a diaphragm 32 and a seat 33 and ,is normally closed, is controlled by a normally open check valve 36 in a bleed line 35 connecting a control chamber 34 of the surge valve with the heat pressure line 28. At a predetermined low ambient pressure an aneroid 37 closes the check valve 36 and opens a vent in the bleed line so that pressure in the surge valve control chamber is reduced and the surge valve passes a pressure pulse via the closure valve 38 to the outlet. The closure valve 38 which also comprises a diaphragm 41 and a seat 39 is opened by the pulse against the pressure in its control chamber but closes when the pressure in its control chamber has built up under the control of a needle valve 44. The main supply valve, which is operated by a diaphragm 47, is controlled by the pressure ,in a chamber 48 which is normally supplied with gas from the second line 29 through a bleed line 49 and a needle valve 52 and is vented through a passage 51 controlled by a needle valve 54 which may be controlled by a spring-urged piston 57 or adjustably fixed (Fig. 3). Normally gas escapes from the chamber 48 at a rate greater than it enters so that the supply valve is closed. Under the control of an aneroid 53, the needle valve 52 permits an increase of gas flow to the chamber 48 with decrease of ambient pressure so that the main supply valve 45 opens. The needle valve 54 may be operated by the piston 57 which tends to close the valve against the supply pressure communicated to it through a conduit 62. On increased demand, the needle valve 54 tends to close the vent 51 so that the pressures of gas in the chamber 48 and passing through the supply valve increase. A manual override needle valve 55 permits the chamber 48 to be disconnected from the vent so that the main supply valve opens.