Respiratory gas controller for breathing mask - uses fluidic impact amplifier in which disturbance of laminar jet controls inlet supply valve

摘要

A source of compressed respiratory gas is supplied to a breathing mask (12) through a supply pipe (14) and valve (16). The valve (16) is controlled from a fluidic impact amplifier (20) having an inlet supply tube (22) coaxial with a receiving tube (24) which feeds gas to the valve to effect control actions. The amplifier is supplied via a connection to the compressed gas supply through an adjustable restrictor (28). This supply to the amplifier inlet tube provides a laminar flow which puts the receiving tube under pressure. A very small diameter orifice (32) communicates with the mask through a tube (34). This orifice (32) is perpendicular to the jet to modify its flow such that depressurisation in the mask causes turbulence to reduce the jet pressure. This causes the supply valve to open and allow more respiratory gas to enter the mask.