| abstract |
A primary control valve when open permits the flow of a pressurized oxygen containing gas from a source to a patient adapter for use by the patient. A pressure control means controls the opening of the primary valve and is responsive to a subambient pressure in the adapter caused by initial patient inhalation to actuate the primary valve to an open position. A pair of adjustable timing mechanisms control the lapse time for the primary valve in the open or closed position. The timing mechanism controlling the time during which the primary valve is closed is subservient to the pressure control means so that patient inhalation causes the valve to open prior to the preselected lapse time. It may also be turned off to permit gas flow only as a result of patient inhalation. A pressure regulator is also provided to prevent flow pressures in the adapter above a predetermined level. A mechanism is also provided to adjust the level of output flow to meet varying patient needs. |