rebreather training on closed circuit scuba diving system

A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycled exhaled gas. This recycling reduces the volume of breathing gas used, making a rebreather lighter and more compact than an open-circuit breathing set for the same duration in environments where humans cannot safely breathe from the atmosphere. In the armed forces it is sometimes called "CCUBA" (Closed Circuit Underwater Breathing Apparatus).

Rebreather technology is used in many environments:

* Underwater - where it is sometimes known as CCR = "closed circuit rebreather", "closed circuit scuba", "semi closed scuba", SCR = "semi closed rebreather", or CCUBA = "closed circuit underwater breathing apparatus", as opposed to Aqua-Lung-type equipment, which is known as "open circuit scuba".
* Mine rescue and in industry - where poisonous gases may be present or oxygen may be absent.
* Crewed spacecraft and space suits - outer space is, for all intents and purposes, a vacuum where there is no oxygen to support life.
* Hospital anaesthesia breathing systems - to supply controlled proportions of gases to patients without letting anaesthetic gas get into the atmosphere that the staff breathe.
Around 1620 in England, Cornelius Drebbel made an early oar-powered submarine. Records show that, to re-oxygenate the air inside it, he likely generated oxygen by heating saltpetre (sodium or potassium nitrate) in a metal pan to make it emit oxygen. That would turn the saltpetre into sodium or potassium oxide or hydroxide, which would tend to absorb carbon dioxide from the air around. That may explain how Drebbel's men were not affected by carbon dioxide build-up as much as would be expected. If so, he accidentally made a crude rebreather nearly three centuries before Fleuss and Davis.

In 1853 Professor T. Schwann designed a rebreather in Belgium; he exhibited it in Paris in 1878.[4]

In 1878 Henry Fleuss invented the first certainly known rebreather using stored oxygen and absorption of carbon dioxide by an absorbent (here rope yarn soaked in caustic potash solution), to rescue mineworkers who were trapped by water.

The Davis Escape Set was the first rebreather which was practical for use and produced in quantity. It was designed about 1900 in Britain for escape from sunken submarines. Various industrial oxygen rebreathers (e.g. the Siebe Gorman Salvus and the Siebe Gorman Proto, both invented in the early 1900s) were descended from it; this link shows a Draeger rebreather used for mines rescue in 1907.

In 1903 to 1907 Professor Georges Jaubert, invented Oxylithe, which is a form of sodium peroxide (Na2O2) or sodium dioxide (NaO2). As it absorbs carbon dioxide it emits oxygen. In 1909 Captain S.S. Hall, R.N., and Dr. O. Rees, R.N., developed a submarine escape apparatus using Oxylithe; the Royal Navy accepted it. It was used for shallow water diving but never in a submarine escape[6]; it was used in the first filming (1907) of Twenty Thousand Leagues Under the Sea.

The first known systematic use of rebreathers for diving was by Italian sport spearfishers in the 1930s. This practice came to the attention of the Italian Navy, which developed its frogman unit Decima Flottiglia MAS, which was used effectively in World War II.

In World War II captured Italian frogmen's rebreathers influenced design of British frogmen's rebreathers.[6] Many British frogmen's breathing sets' oxygen cylinders were German pilot's oxygen cylinders recovered from shot-down German Luftwaffe planes. Those first breathing sets may have been modified Davis Submarine Escape Sets; their fullface masks were the type intended for the Siebe Gorman Salvus. But in later operations different designs were used, leading to a fullface mask with one big face window, at first oval like in this image, and later rectangular (mostly flat, but the ends curved back to allow more vision sideways). Early British frogman's rebreathers had rectangular breathing bags on the chest like Italian frogman's rebreathers; later British frogman's rebreathers had a square recess in the top so they could extend further up onto his shoulders; in front they had a rubber collar that was clamped around the absorbent canister, as in the illustration below.

Some British armed forces divers used bulky thick diving suits called Sladen suits; one version of it had a flip-up single window for both eyes to let the user get binoculars to his eyes when on the surface.

In the early 1940s US Navy rebreathers were developed by Dr. Christian J. Lambertsen for underwater warfare and is considered by the US Navy as "the father of the Frogmen".[ Lambertsen held the first closed-circuit oxygen rebreather course in the United States for the Office of Strategic Services maritime unit at the Naval Academy on 17 May 1943