page_title: Rebreather
section_title: Oxygen rebreathers
hierarchical_section_title: Rebreather / System variants / Oxygen rebreathers
caption_attribution_description: English: Schematic diagram of a closed cirduit oxygen rebreather with a pendulum configuration and radial flow scrubber 1 Dive/surface valve 2 Two way breathing hose 3 Scrubber (radial flow) 4 Counterlung 5 Automatic make-up valve 6 Manual bypass valve 7 Breathing gas storage cylinder 8 Cylinder valve 9 Regulator first stage 10 Submersible pressure gauge 11 Ovepressure valve
context_page_description: A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is added to replenish the amount metabolised by the user. This differs from open-circuit breathing apparatus, where the exhaled gas is discharged directly into the environment. The purpose is to extend the breathing endurance of a limited gas supply, and, for covert military use by frogmen or observation of underwater life, eliminating the bubbles produced by an open circuit system. A rebreather is generally understood to be a portable unit carried by the user. The same technology on a vehicle or non-mobile installation is more likely to be referred to as a life-support system.
  Rebreather technology may be used where breathing gas supply is limited, such as underwater or in space, where the environment is toxic or hypoxic, as in firefighting, mine rescue and high-altitude operations, or where the breathing gas is specially enriched or contains expensive components, such as helium diluent or anaesthetic gases.
context_section_description: This is the earliest type of rebreather and was commonly used by navies and for mining rescue from the early twentieth century. Oxygen rebreathers can be remarkably simple designs, and they were invented before open-circuit scuba. They only supply oxygen, so there is no requirement to control the gas mixture other than removing the carbon dioxide.
caption: Schematic diagram of a closed circuit oxygen rebreather with a pendulum configuration and radial flow scrubber1 Dive/surface valve2 Two way breathing hose3 Scrubber (radial flow)4 Counterlung5 Automatic make-up valve6 Manual bypass valve7 Breathing gas storage cylinder8 Cylinder valve9 Regulator first stage10 Submersible pressure gauge11 Overpressure valve
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