GB1004032A - A non-return valve - Google Patents

Abstract

1,004,032. Fluid-pressure control valves &c. E. P. V. R. GODEL. March 20, 1962, No. 10698/62. Heading F2V. [Also in Division A5] An exhaust valve primarily for a respiratory mask for high altitude use is associated with a pressure-sensitive device connected to the supply source so that the opening pressure is dependent on the supply pressure, but also having means for preventing communication between the mask and atmosphere if the supply pressure falls to atmospheric. In one form the valve assembly shown in Fig. 1 is fitted into an aperture in the wall of a face-mask the wall being gripped between a flange 2 and the adjacent flange on a cover member 4, and exhaled air passes through orifices in the cover 4, between a valve seating 13 and a plate valve 11 to a chamber 12 and out to atmosphere through apertures 5. The valve 11 tends to be held closed by expansion of a bellows 27 which bears upwards against it owing to internal pressure of gas received through pipe 35 connected to the supply. Thus any change in the pressure of gas fed into the mask is balanced by a corresponding change in the thrust exerted on the valve by the bellows. If, however, the pressure of the gas supply falls to atmospheric pressure the valve 11 is still maintained closed by a light spring 36 connected between the bellows and the valve. In another embodiment described with reference to Fig. 4 the natural resilience of the bellows is employed to hold the valve closed under these conditions. This may be adjusted by screwing the tube 21, carrying the bellows 27, towards or away from the seating 6. In this form the tube 21 is additionally employed to supply gas to the face-mask, an inlet valve 51 being opened at each inhalation of the user.