| abstract |
The invention provides a breathable gas regulator of the demand type for use with a low supply pressure (10 p.s.i or less) gas source. n The regulator requires no greater demand effort on the part of a user than is required with present-day regulators of the same type which operate with much higher pressure (70 p.s.i. and above) gas sources, and it requires ducts, diaphragms and valves of no greater size than are required by present-day regulators. This is achieved by inclusion of a servo valve that is actuated by a fluidic amplifier arrangement responsive to the user's breathing pressure. n In an embodiment of the invention particularly suited for use by an aviator, the regulator includes a pneumatically operated mixing valve arrangement for automatically varying, according to altitude, the proportions of, say, oxygen and air supplied to the demand valve of the regulator, and the mixing valve arrangement includes a fluidic gas concentration sensor. |