Scuba Diving Rebreathers

The name pretty much speaks for itself - a device that recycles exhaled breath and provides oxygen. Rebreathers, or Underwater Closed Circuit Rebreathers, have no less than one alternate source of compressed air. These are usually smaller due to the generally lowered levels of air consumption.

They are used most commonly in closed and semi closed circuit diving. Also used in mine rescue expeditions for protection against poisons and lack of oxygen as well as by NASA astronauts in space and in submarines among other.

SCUBA stands for Self Contained Underwater Breathing Apparatus- defining the self sustaining system used to facilitate breathing for the duration of the dive. Open circuit scuba doesn't make use of rebreathers (recycled air) whereas closed and semi closed do.

Open circuit gas supply is primarily air whereas closed circuit scuba uses a mixture or recycled gas and air. These contain a cylinder and regulator. The advantages of rebreathers include buoyancy control due to low equipment usage and requirements as it is not necessary to lug extra tanks on deeper dives. An extra source must be taken in the event that the rebreather fails for bail out. The disadvantages are they are rather complex and vulnerable to damage

Inhalation in the human body requires a process of oxygen for breathe and carbon dioxide exhalation. Open circuit systems support using a lower ratio (about a quarter) of oxygen due to the recycling process saving precious air, absorbing potentially poisonous carbon dioxide via a canister containing chemical absorbents designed for absorption.

The necessary diluents are also added to the oxygen to maintain the safety inhalation chemical equilibrium below the required 6 m after which pure oxygen inhalation too becomes poisonous.