Abstract: A SCBA with an air storage, a face piece with inner mask (nose cup), breathing regulator(s), a breathing valve, an exhalation valve operating at positive pressure relative to the ambient and a reservoir capable of storing the first part of an exhalation and delivering that part at the subsequent inhalation. The reservoir is positioned in the SCBA's face piece or in close proximity thereto, is in fluid contact with the inner mask, and has a shut-off valve controlled by a carbon-dioxide sensor. The operating pressure of the reservoir is maintained above ambient pressure and the operating pressure of the reservoir is between the opening pressure of the SCBA's breathing valve and the SCBA's exhalation valve.

Abstract: The invention concerns a system and a method for supplying breathing gas to a diver. The system is of the open circuit type and comprises a gas source consisting of a pressurized container (1), which is intended to be placed at a distance from the diver and which delivers breathing gas under a high pressure, a breathing apparatus (4) which is intended to be carried by the diver and a flexible tube (3), which connects the gas source with the breathing apparatus. The flexible tube is of the high-pressure type, the gas is conducted through the flexible tube under a pressure, which is essentially equal to the pressure delivered from the gas source, and the gas source is arranged to be able to deliver breathing gas at a pressure, which exceeds approx. 30 bars.

Abstract: Breathing apparatus is provided for use under water which comprises a connection device such as a helmet, mask, or the like and a breathing circuit in communication with the connection device. The breathing circuit includes a carbon-dioxide absorber and an expansible gas chamber, and, in operation, provides a first operating period wherein the breathing circuit is closed and a breathing gas is caused to circulate in the breathing circuit until the oxygen concentration of the circulating breathing gas is reduced to a predetermined value and a second operating period, which alternates with the first, wherein the used breathing gas is released to ambient and a fresh gas, the quantity of which is substantially independent of the depth of the user under the water surface, is applied to the breathing circuit.

Abstract: Breathing apparatus is provided for use under water, in a noxious atmosphere or under like conditions, which provides pressure compensation during release of the consumed breathing gas. The apparatus includes a connection device such as a breathing mask for connecting the apparatus to the breathing organs of a user and a breathing circuit which communicates with the connection device and includes a carbon-dioxide absorber and an expansible gas chamber. The apparatus includes controls which, during the operation of the breathing circuit, provide (i) a first operating period wherein the breathing circuit is closed and a breathing gas is caused to circulate in the breathing circuit until the oxygen concentration of the circulating breathing gas is reduced to a predetermined value and (ii) a second operating period which alternates with the first period, wherein the used breathing gas is released to the ambient environment and fresh gas is supplied to the breathing circuit.