Importance

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Abstract

A portable semi-closed breathing apparatus for divers, having a circuit comprising a breathing bellows (1) connected to a pressure gas source (2) for the supply of breathing gas, a demand-controlled breathing valve (20), an actuator (4) for expansion and contraction of the breathing bellows (1) in step with the diver's breathing pattern, a means (5) for compensation of consumed oxygen, and a means (6) for removal of CO.sub.2 from the breathing gas. The actuator (4) is a cylinder/piston unit (9, 10) having a first chamber (11) connected to a source (13) for compensation gas, and a second chamber (12) connected to a valve means (5). During the diver's exhalation phase the valve means (5) is arranged to supply compensation gas to said second chamber (12) under control of the breathing valve (20), so that the breathing bellows (1) expands and absorbs exhaled gas from the diver. During the inhalation phase the actuator (4) contracts the bellows (1) and the valve means (5) delivers compensation gas to the circuit in accurate correspondence with the gas quantity inhaled by the diver, in that the valve means is arranged to keep the pressure in the second chamber (12) at a preset level.

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First Claim