GB1487676A - Demand regulator for a breathing apparatus - Google Patents

Abstract

1487676 Demand regulator for breathing apparatus R A CHRISTIANSON 19 Sept 1975 [23 Sept 1974 16 June 1975] 38544/75 Heading A5T A demand regulator for scuba breathing apparatus consists of a housing 18 with an inlet 13 from a first stage regulator and an outlet 14 to a face mask, the passage of breathable gas through the housing being controlled by a poppet 34 which co-operates with the open end of a cylindrical valve housing 27, the poppet in turn being controlled by a pilot valve within the poppet and linked with an inhalation sensing diaphragm 23. The pilot valve has a pin 43 which extends through a closed end of the valve housing and is moved by the linkage 55, 57, 58, connecting it to the diaphragm against a spring 51 so that incoming breathable gas passes to the space between the closed end of the valve housing and the poppet to move the poppet to open the passage to the outlet, movement of the poppet against the bias of a spring 41 causing the pilot valve to close. In modifications, Figs. 6 and 7 (not shown), the pilot valve pins are attached to pilot valve bodies provided with O-rings which act as seals but which on movement of the pin allow gas to the space between the poppet and closed end of the valve housing. The bias applied to the pilot valve can be varied by a plug 52 and the gas which passes to the outlet aspirated through an orifice 19c in an adjustable, rotatable cap 19. In a further embodiment, Fig. 8, the pilot valve pin 106 mounts a back up disc 95 which moves when the pin is actuated by the diaphragm to allow gas to pass by a valve seat 93 normally closed by an O-ring 94 and through a passage 103 to the space between the poppet and a closed end of the valve housing. Movement of the pin is limited by a boss 110 and a further pin 111 within the boss contacts the regulator housing should the pilot valve remain open and cause the poppet to open to an extreme position.