Diving rebreather
Closed or semi-closed circuit scuba
A diving rebreather is an underwater breathing apparatus that absorbs the carbon dioxide of a diver's exhaled breath to permit the rebreathing (recycling) 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 diver. 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, to eliminate the bubbles produced by an open circuit system.
A diving rebreather is generally understood to be a portable unit carried by the user, and is therefore a type of self-contained underwater breathing apparatus (SCUBA). A semi-closed rebreather carried by the diver may also be known as a gas extender. The same technology on a submersible, underwater habitat, or surface installation is more likely to be referred to as a life-support system.
Diving rebreather technology may be used where breathing gas supply is limited, or where the breathing gas is specially enriched or contains expensive components, such as helium diluent. Diving rebreathers have applications for primary and emergency gas supply. Similar technology is used in life-support systems in submarines, submersibles, underwater and surface saturation habitats, and in gas reclaim systems used to recover the large volumes of helium used in saturation diving.
“Diving rebreather” enters the record as closed or semi-closed circuit scuba. Crown Archives preserves that source wording while asking what Diving, rebreather and Closed can confirm, complicate or overturn.
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