Special duty oxygen breathing apparatus, a military rebreather.
The SDBA (Special Duty Oxygen Breathing Apparatus) is a type of frogman's rebreather breathing set. Many of the world's navies and army marine corps have used it since 1971.
The breathing bag is square with rounded corners, on his chest, exposed. Its absorbent canister is cylindrical with flat ends, crosswise on his belly, about 10 inches long and 5.3 inches diameter, in a rubber sheath. It has a loop of wide corrugated breathing tubes; one of them originates at each end of the canister; the right tube has a side connection to let gas in and out of the breathing bag as he breathes. It has two long thin oxygen cylinders lengthwise on his back. It can be supplied with a mouthpiece with a neck strap; the mouthpiece has a valve on its front to close the breathing tubes when the mouthpiece is not in his mouth. Its dive duration is about 3 hours.
A scuba set is any breathing apparatus that is carried entirely by an underwater diver and provides the diver with breathing gas at the ambient pressure. Scuba is an anacronym for self-contained underwater breathing apparatus. Although strictly speaking the scuba set is only the diving equipment which is required for providing breathing gas to the diver, general usage includes the harness by which it is carried, and those accessories which are integral parts of the harness and breathing apparatus assembly, such as a jacket or wing style buoyancy compensator and instruments mounted in a combined housing with the pressure gauge, and in the looser sense it has been used to refer to any diving equipment used by the scuba diver, though this would more commonly and accurately be termed scuba equipment or scuba gear. Scuba is overwhelmingly the most common underwater breathing system used by recreational divers and is also used in professional diving when it provides advantages, usually of mobility and range, over surface supplied diving systems, and is allowed by the relevant code of practice.
A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is added to replenish the amount metabolised by the user. This differs from open-circuit breathing apparatus, where the exhaled gas is discharged directly into the environment. The purpose is to extend the breathing endurance of a limited gas supply, and, for covert military use by frogmen or observation of underwater life, eliminating the bubbles produced by an open circuit system. A rebreather is generally understood to be a portable unit carried by the user. The same technology on a vehicle or non-mobile installation is more likely to be referred to as a life-support system.
A diving regulator is a pressure regulator that controls the pressure of breathing gas for diving. The most commonly recognised application is to reduce pressurized breathing gas to ambient pressure and deliver it to the diver, but there are also other types of gas pressure regulator used for diving applications. The gas may be air or one of a variety of specially blended breathing gases. The gas may be supplied from a scuba cylinder carried by the diver or via a hose from a compressor or high-pressure storage cylinders at the surface in surface-supplied diving. A gas pressure regulator has one or more valves in series which reduce pressure from the source, and use the downstream pressure as feedback to control the delivered pressure, or the upstream pressure as feedback to prevent excessive flow rates, lowering the pressure at each stage.
The Soviet, later Russian IDA71 military and naval rebreather is an oxygen rebreather intended for use by naval and military divers including Russian commando frogmen. As supplied it is in a plain backpack harness with no buoyancy aid. The casing is pressed aluminium with a hinged cover. It has a small optional nitrox cylinder which can be clipped on its outside to convert it to nitrox mode. It contains one oxygen cylinder and two absorbent canisters. In the bottom of its casing is an empty space which is intended for an underwater communications set.
The Clearance Divers Breathing Apparatus (CDBA) is a type of rebreather made by Siebe Gorman in England.
The Siebe Gorman Salvus is a light oxygen rebreather for industrial use or in shallow diving. Its duration on a filling is 30 to 40 minutes. It was very common in Britain during World War II and for a long time afterwards. Underwater the Salvus is very compact and can be used where a diver with a bigger breathing set cannot get in, such as inside cockpits of ditched aircraft. It was made by Siebe Gorman & Company, LTD in London, England. It was designed in the early 1900s.
Siebe Gorman & Company Ltd was a British company that developed diving equipment and breathing equipment and worked on commercial diving and marine salvage projects. The company advertised itself as 'Submarine Engineers'. It was founded by Augustus Siebe, a German-born British engineer chiefly known for his contributions to diving equipment.
Drägerwerk AG is a German company based in Lübeck which makes breathing and protection equipment, gas detection and analysis systems, and noninvasive patient monitoring technologies. Customers include hospitals, fire departments and diving companies.
A Mark IV Amphibian is an early model of British naval oxygen rebreather made by Siebe Gorman. It was arranged like a UBA, but its oxygen cylinder is smaller. It was so called because it could be used for diving, or as an industrial breathing set on land.
Cis-Lunar is a firm that made computer-controlled closed-circuit automatic rebreathers for scuba diving. Some of its production models were in a streamlined casing. The firm's first plan was to develop spacesuit kit. The dot com crash in early 2000 prevented Cis-Lunar from financing mass production of the MK5 rebreather. The MK5 included design elements aimed at preventing system and mission failures.
Porpoise is a tradename for scuba developed by Ted Eldred in Australia and made there from the late 1940s onwards. The first Porpoise was a closed circuit oxygen rebreather, and the following models were all single hose open circuit regulators.
The Davis Submerged Escape Apparatus, was an early type of oxygen rebreather invented in 1910 by Sir Robert Davis, head of Siebe Gorman and Co. Ltd., inspired by the earlier Fleuss system, and adopted by the Royal Navy after further development by Davis in 1927. While intended primarily as an emergency escape apparatus for submarine crews, it was soon also used for diving, being a handy shallow water diving apparatus with a thirty-minute endurance, and as an industrial breathing set.
The Proto is a type of rebreather that was made by Siebe Gorman. It was an industrial breathing set and not suitable for diving. It was made from 1914 or earlier to the 1960s or later.. Also known as proto suits.
An escape set is a breathing set that allows its wearer to survive for a time in an environment without (sufficiently) breathable air.
Vintage scuba is scuba equipment dating from 1975 and earlier, and the practice of diving using such equipment.
The Lambertsen Amphibious Respiratory Unit (LARU) is an early model of closed circuit oxygen rebreather used by military frogmen. Christian J. Lambertsen designed a series of them in the US in 1940 and in 1944.
Rebreather diving is underwater diving using diving rebreathers, a class of underwater breathing apparatus which recirculate the breathing gas exhaled by the diver after replacing the oxygen used and removing the carbon dioxide metabolic product. Rebreather diving is practiced by recreational, military and scientific divers in applications where it has advantages over open circuit scuba, and surface supply of breathing gas is impracticable. The main advantages of rebreather diving are extended gas endurance, low noise levels, and lack of bubbles.
The history of underwater diving starts with freediving as a widespread means of hunting and gathering, both for food and other valuable resources such as pearls and coral, By classical Greek and Roman times commercial applications such as sponge diving and marine salvage were established, Military diving also has a long history, going back at least as far as the Peloponnesian War, with recreational and sporting applications being a recent development. Technological development in ambient pressure diving started with stone weights (skandalopetra) for fast descent. In the 16th and 17th centuries diving bells became functionally useful when a renewable supply of air could be provided to the diver at depth, and progressed to surface supplied diving helmets—in effect miniature diving bells covering the diver's head and supplied with compressed air by manually operated pumps—which were improved by attaching a waterproof suit to the helmet and in the early 19th century became the standard diving dress.
The history of scuba diving is closely linked with the history of scuba equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from the exhaled breathing gas, which is then recirculated, and more gas added to replenish the oxygen content. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid-twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented a free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA, an acronym for "self-contained underwater breathing apparatus," which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity.
A Diving rebreather is an underwater breathing apparatus that absorbs the carbon dioxide of a diver's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is added to replenish the amount metabolised by the diver. This differs from open-circuit breathing apparatus, where the exhaled gas is discharged directly into the environment. The purpose is to extend the breathing endurance of a limited gas supply, and, for covert military use by frogmen or observation of underwater life, to eliminate the bubbles produced by an open circuit system. A diving rebreather is generally understood to be a portable unit carried by the user, and is therefore a type of self-contained underwater breathing apparatus (scuba). A semi-closed rebreather carried by the diver may also be known as a gas extender. The same technology on a submersible or surface installation is more likely to be referred to as a life-support system.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
