Underwater breathing apparatus

Underwater breathing apparatus
	A museum display of a variety of different underwater breathing apparatus configurations
Acronym	UBA
Uses	provision of breathing gas to an underwater diver
Related items	Breathing apparatus, diving equipment, life-support equipment

Underwater breathing apparatus is equipment which allows the user to breathe underwater. The three major categories of ambient pressure underwater breathing apparatus are:

Open circuit scuba, where the diver carries the gas supply, and exhaled gas is exhausted to the environment^[1]
Diving rebreather, where the diver carries the gas supply, and exhaled gas is recycled for further use,^[1] and
Surface-supplied diving equipment, where the gas supply is provided from the surface through a hose, usually in a diver's umbilical,^[1] but also sometimes from a simple air hose.

Two other types may also be identified:

Escape sets provide a limited amount of breathing gas to allow the user to reach the surface from a disabled vessel or vehicle.^[2]
Atmospheric pressure underwater breathing apparatus is also used in the form of armoured atmospheric diving suits, which maintain an internal pressure approximating surface pressure.^[3]

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