GB640316A - Respiratory apparatus - Google Patents

Abstract

640,316. Respiratory appliances. MANDET, Y. J. B. Feb. 5, 1948, No. 3389. Convention date, Nov. 27, 1947. [Class 81(ii)] [Also in Group XXIX] Between the high pressure air or gas supply of a respiratory appliance and the mask is placed a pressure regulator comprising two stages in series, one reducing the pressure to slightly greater than atmospheric and the other supplying respiratory air at a pressure equal to the surrounding atmosphere. In the first stage a loading spring 9 adjusted by a screwed cap 22 and pressing on a relatively small diaphragm 6 acts through a bell crank 7 and pin 26 to tend to lift a valve 5 off its seating, against a returning spring 5a. The size of the diaphragm 6 and the loading of the spring 9 are such that the pressure in the chamber 2 is slightly above atmospheric. The second chamber 3 communicates with the face mask through a hose connection 16 and has one wall formed by a diaphragm 11 open to atmospheric pressure on its outer face. When the wearer breathes in the rarefaction in this chamber causes the diaphragm to bow inwards and depress the lever 13, with the result that an arm on a pivot 14 actuating a pin 27, lifts the secondary valve 15 off its seating to allow air to pass to chamber 3. Immediately the pressure in this chamber rises to atmospheric the valve again closes. To overcome losses in the outlet pipe a light spring may press on the outer face of diaphragm 11.