Self Contained Underwater Breathing Apparatus

Last updated: November 20, 2013

What Does Self Contained Underwater Breathing Apparatus Mean?

A self-contained underwater breathing apparatus (SCUBA) is a type of portable underwater breathing equipment used by industrial, amateur and military divers. It provides breathable air at ambient pressure through a regulator and a tube to the mouth of the diver from one or two bottles that contain compressed air.

Safeopedia Explains Self Contained Underwater Breathing Apparatus

SCUBA is a very common and popular type of underwater breathing equipment. A SCUBA set consists of the following parts:

  • A single or a pair of high-pressure (300 bars) air tanks made of steel, aluminum or carbon-fiber composite
  • One pressure regulator
  • A mouthpiece and connecting tubes
  • A carrying frame, pack or harness

There are three different types of SCUBA:

  • Open-circuit SCUBA provides decompressed breathable air from tanks through regulators and a mouthpiece. The exhaled air from the diver’s mouth is directly released into the water.
  • Closed-circuit SCUBA, also known as a "rebreather," removes the carbon dioxide from the diver’s exhaled air and replaces it with oxygen. This mixture is then passed to the inhalation bag, and is ready to be rebreathed by the diver. This allows the diver to stay underwater for much longer periods (few hours) than open-circuit SCUBA.
  • Semi-closed-circuit mixed gas SCUBA uses the same technique that removes the carbon dioxide as the closed circuits, but the breathing medium continues to flow until it becomes fully useless. It is then completely released into the water and replaced by new, fresh air.

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