GB959589A - Compensated expiratory valves - Google Patents

Abstract

959,589. Expiratory valves for oxygen masks. BEAGLE-AUSTER AIRCRAFT Ltd. April 4, 1962 [Jan. 16, 1961], No. 1810/61. Heading A5T. [Also in Division G3] A compensated expiratory valve for an oxygen mask includes a valve body 11 having a partition wall 16 dividing a compensating pressure compartment 18 from the rest of the valve, a resiliently mounted primary diaphragm 14 connecting the orifice 21 of the mask with primary exhaust ports 22, an inlet 19 situated between the wall 16 and the diaphragm 14 to admit oxygen to the compartment 18, a secondary diaphragm 23 resiliently mounted in a chamber 25 to actuate a mushroom valve 30 which opens and closes ports 31 in the wall 16 which connect the compartment 18 with secondary exhaust ports 26, there being a bleed-hole 28 in the valve body 11 on the/or side of the diaphragm 23. The diaphragms operate against light springs 20 and 32. In the event of rapid reduction of pressure in the pressurized cabin of an aircraft in which the mask is used, the pressure in the chamber 25 will fall faster than that in the compartment 27 so that the mushroom valve 30 will open and vent pressure from the compartment 18 through the ports 26. This will, in turn, allow the diaphragm 14 to open for a period and allow air to be vented from the wearer's lungs to equalize with the external pressure drop. Fig. 2 (not shown), illustrates an embodiment in which the diaphragm 14 is constructed in two parts with a spring between them so that the diaphragm 14 does not open in the event of a failure of the oxygen supply.