GB832281A - Improvements in or relating to breathing apparatus - Google Patents

Abstract

832,281. Respiratory apparatus. NORMALAIR Ltd. May 9, 1958 [July 25, 1957], No. 23539/57. Class 81 (2). [Also in Group XXVIII] An oxygen/air supply device for a demand regulator comprises a nozzle for discharging oxygen from an inlet towards an oxygen/air outlet, an air inlet, a valve seating around the nozzle and a resilient non-return valve disc on the seating and subjected to a pressure differential of oxygen inlet pressure and breathing pressure. The device fitted in a demand regulator A receives oxygen supplied under pressure through a valve 11 opened by a long-controlled diaphragm 3, and a conduit 19. Oxygen flows to an injector e in a casing a and through a nozzle h to a chamber p where it entrains air through holes o communicating with an air inlet 13 of the demand regulator. Holes l, k in the injector communicate with a compartment g which is separated from the chamber p by a resilient, apertured valve disc m which normally seats against the nozzle. When oxygen pressure in the compartment g overcomes the pressure in the chamber p, as on increased demand, the valve disc is deformed to permit the passage of supplementary oxygen from the compartment g to the chamber p. Oxygen and air passes from the chamber p to a mixing tube c and thence into inhalation pipe 7. A known form of injector is described which has a nozzle slidable against a spring in a casing. When the back pressure on the nozzle is overcome, the nozzle slides forwards and permits supplementary oxygen to flow from the injector tube into the regulator compartment 2 (Fig. 1), and thence into the inhalation tube.