The situation is even more wasteful of oxygen when the oxygen fraction of the breathing gas is higher, and in underwater diving, the compression of breathing gas due to depth makes the recirculation of exhaled gas even more desirable, as an even larger proportion of open circuit gas is wasted. Exhaled air at sea level contains roughly 13.5% to 16% oxygen. Base metabolism requires about 0.25 L/min of oxygen from a breathing rate of about 6 L/min, and a fit person working hard may ventilate at a rate of 95 L/min but will only metabolise about 4 L/min of oxygen The oxygen metabolised is generally about 4% to 5% of the inspired volume at normal atmospheric pressure, or about 20% of the available oxygen in the air at sea level. 7.1.4 Fire hazards of high concentration of oxygenĪs a person breathes, the body consumes oxygen and produces carbon dioxide.7.1.3 Leakage of toxic gases into the breathing loop.6.5 Rebreathers for unpressurised aircraft and high altitude parachuting.6.2 Industrial and rescue self-contained rebreathers.6.1.2 Saturation diving life-support systems.6.1.1 Surface supplied diving gas reclaim systems.5.4 Rebreathers which use liquid oxygen.5.3 Rebreathers using an absorbent that releases oxygen.5.2.2 Closed circuit mixed gas rebreathers.5.2.1.2.1 Demand controlled gas addition.5.2.1.2 Active addition semi-closed circuit.5.2.1.1 Passive addition semi-closed circuit.Electronically controlled diving rebreathers may automatically maintain a partial pressure of oxygen between programmable upper and lower limits, or set points, and be integrated with decompression computers to monitor the decompression status of the diver and record the dive profile. Mass and bulk may be greater or less than open circuit depending on circumstances. The recycling of breathing gas comes at the cost of technological complexity and specific hazards, some of which depend on the application and type of rebreather used. Similar technology is used in life-support systems in submarines, submersibles, underwater and surface saturation habitats, spacecraft, and space stations, and in gas reclaim systems used to recover the large volumes of helium used in saturation diving. In aerospace there are applications in unpressurised aircraft and for high altitude parachute drops, and off-planet, in space suits for extra-vehicular activity. On land they are used in industrial applications where poisonous gases may be present or oxygen may be absent, firefighting, where firefighters may be required to operate in an atmosphere immediately dangerous to life and health for extended periods, and in hospital anaesthesia breathing systems to supply controlled concentrations of anaesthetic gases to patients without contaminating the air that the staff breathe, and at high altitude, where the partial pressure of oxygen is low, for high altitude mountaineering. Rebreathers are used in many environments: Underwater, diving rebreathers are a type of self-contained underwater breathing apparatus which have applications for primary and emergency gas supply. 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. The same technology on a vehicle or non-mobile installation is more likely to be referred to as a life-support system.
Aqua aquarius tradução portable#
A rebreather is generally understood to be a portable unit carried by the user. 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. This differs from open-circuit breathing apparatus, where the exhaled gas is discharged directly into the environment. Oxygen is added to replenish the amount metabolised by the user. A fully closed circuit electronic rebreather ( AP Diving Inspiration)ĬCUBA (closed circuit underwater breathing apparatus) CCR (closed circuit rebreather), SCR (semi-closed rebreather)Ī rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath.
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