From Wikipedia, the free encyclopedia
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
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
- 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
- Hospital anaesthesia breathing systems – to supply controlled
proportions of gases to patients without letting anaesthetic gas
get into the atmosphere that the staff breathe.
- Himalayan mountaineering. Both chemical and compressed oxygen
has been used in experimental closed-circuit oxygen systems—the
first on Mt. Everest in 1938. A high rate of system failures due
to extreme cold has not been solved.
As a person breathes, the body consumes oxygen and makes carbon
dioxide. At shallow depths, a person with an open-circuit breathing
set typically only uses about a quarter of the oxygen in the air
that is breathed in (4%–5% of the inspired volume). The remaining
oxygen is exhaled along with nitrogen and carbon dioxide. As the
diver goes deeper, roughly the same quantity of oxygen is used,
which represents an increasingly smaller fraction of the compressed
air breathed in. Because exhaled air can contain as much as 79%
nitrogen (which is not utilized in the body) and 16% (or more) unused
oxygen, every exhaled breath from an open-circuit scuba set represents
at least 95% wasted, potentially useful gas volume, which has to
be replaced from the air supply.
The rebreather recirculates the exhaled gas for re-use and does
not discharge it to the atmosphere or water. It absorbs the carbon
dioxide, which otherwise would accumulate and cause carbon dioxide
poisoning. It removes the carbon dioxide by a process called scrubbing.
The rebreather adds oxygen, to replace the oxygen that was consumed.
Thus, the gas in the rebreather's circuit remains breathable and
supports life and the diver needs only a fraction of the gas that
would be required for an open-circuit system.
History of rebreathers
Around 1620: In England, Cornelius Drebbel made an early oar-powered
submarine. To re-oxygenate the air inside it, he likely generated
oxygen by heating saltpetre (potassium nitrate) in a metal pan to
emit oxygen. Heating turns the saltpetre into potassium oxide or
hydroxide, which absorbs carbon dioxide from the air. That may explain
why 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
more than two centuries before Saint Simon Sicard's patent.
1808: The oldest known rebreather based on carbon dioxide absorption
was patented in France by Sieur (old French for "sir"
or "Mister") Touboulic from Brest, mechanic in the Napoleon's
Imperial Navy. This early rebreather design worked with an oxygen
reservoir, the oxygen being delivered progressively by the diver
himself and circulating in a closed circuit through a sponge soaked
in lime water. Touboulic called his invention Ichtioandre (Greek
for 'fish-man').There's no evidence of a prototype having been manufactured.
1849: Patent for the oldest known prototype of a rebreather also
used an oxygen reservoir, granted to the Frenchman Pierre Aimable
De Saint Simon Sicard.
1853: Professor T. Schwann designed a rebreather in Belgium; he
exhibited it in Paris in 1878. It had a big backpack oxygen tank
at pressure about 13.333 bars, and two scrubbers containing sponges
soaked in caustic soda.
1878: Henry Fleuss invented a 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
About 1900: The Davis Escape Set was designed in Britain for escape
from sunken submarines. It was the first rebreather which was practical
for use and produced in quantity. Various industrial oxygen rebreathers
(e.g. the Siebe Gorman Salvus and the Siebe Gorman Proto, both invented
in the early 1900s) were derived from it.
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 (e.g. in a rebreather's scubber) it emits
1907: Oxylithe was used in the first filming of Twenty Thousand
Leagues Under the Sea.
1907: This link shows a Draeger rebreather used for mines rescue.
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
1912: The first recorded mass production of rebreathers started
with the Drager rebreathers, invented some years earlier by an engineer
of the Drager company, Hermann Stelzner. The Drager rebreathers,
especially the DM20 and DM40 model series, were those used by the
German helmet divers and German frogmen during World War II.
1930's: Italian sport spearfishers used rebreathers systematically.
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.
World War II: Captured Italian frogmen's rebreathers influenced
design of British rebreathers. 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
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.