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Saturation diving is a diving technique that allows divers to reduce the risk of decompression sickness ("the bends") when they work at great depths for long periods of time. Decompression sickness occurs when a diver with a large amount of inert gas dissolved in the body tissues is decompressed to a pressure where the gas forms bubbles which may block blood vessels or physically damage surrounding cells. This is a risk on every decompression, and limiting the number of decompressions can reduce the risk. "Saturation" refers to the fact that the diver's tissues have absorbed the maximum partial pressure of gas possible for that depth due to the diver being exposed to breathing gas at that pressure for prolonged periods. This is significant because once the tissues become saturated, the time to ascend from depth, to decompress safely, will not increase with further exposure. In saturation diving, the divers live in a pressurized environment, which can be a saturation system or "saturation spread", a hyperbaric environment on the surface, or an ambient pressure underwater habitat. This may be maintained for up to several weeks, and they are decompressed to surface pressure only once, at the end of their tour of duty. By limiting the number of decompressions in this way, the risk of decompression sickness is significantly reduced. ==History== On December 22, 1938, Edgar End and Max Nohl made the first intentional saturation dive by spending 27 hours breathing air at 101 feet (30.8 m) in the County Emergency Hospital recompression facility in Milwaukee, Wisconsin. Their decompression lasted five hours leaving Nohl with a mild case of decompression sickness that resolved with recompression. Albert R. Behnke proposed the idea of exposing humans to increased ambient pressures long enough for the blood and tissues to become saturated with inert gases in 1942. In 1957, George F. Bond began the Genesis project at the Naval Submarine Medical Research Laboratory proving that humans could in fact withstand prolonged exposure to different breathing gases and increased environmental pressures.〔 Once saturation is achieved, the amount of time needed for decompression depends on the depth and gases breathed. This was the beginning of saturation diving and the US Navy's Man-in-the-Sea Program. The first commercial saturation dives were performed in 1965 by Westinghouse to replace faulty trash racks at 200 feet (61 m) on the Smith Mountain Dam.〔 Peter B. Bennett is credited with the invention of trimix breathing gas as a method to eliminate high pressure nervous syndrome. In 1981, at Duke University Medical Center, Bennett conducted an experiment called Atlantis III, which involved taking divers to a depth of 2,250 feet (685.8 m), and slowly decompressing them to the surface over a period of 31-plus days, setting an early world record for depth in the process. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「saturation diving」の詳細全文を読む スポンサード リンク
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