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Saturation diving is a diving technique that allows divers to remain at great depth for long periods of time. [1][2]

"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. In a mixture of Ideal gases each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume Air is the most common and only natural breathing gas. Other artificial gases either pure gases or mixtures of gases are used in breathing equipment and enclosed habitats such Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface This is significant because once the tissues become saturated, the time to ascend from depth, to decompress safely, will not increase with further exposure.

Commonly, saturation diving allows professional divers to live and work at depths greater than 50 meters / 165 feet for days or weeks at a time. Hardhat diving redirects here Often "hardhat diving" is used to specifically mean diving in the old-type Standard diving dress. This type of diving allows for greater economy of work and enhanced safety for the divers. [1] After working in the water, they rest and live in a dry pressurized habitat on or connected to a diving support vessel, oil platform or other floating work station, at the same pressure as the work depth. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface A diving support vessel is a Ship that is used as a floating base for Professional diving projects An oil platform or oil rig is a large structure used to house workers and machinery needed to drill and/or extract oil and Natural gas through wells [1] The diving team is only compressed to the working pressure once, and decompressed to surface pressure once, over the entire work period of days or weeks.

The "Saturation System" typically comprises a living chamber, transfer chamber and submersible decompression chamber, which is commonly referred to in commercial diving and military diving as the diving bell[3], PTC, Personnel Transfer Capsule or SDC, Submersible Decompression Chamber. A decompression chamber is a Pressure vessel used in Surface supplied diving to allow the divers to complete their Decompression stops at the end of a dive Hardhat diving redirects here Often "hardhat diving" is used to specifically mean diving in the old-type Standard diving dress. A frogman is someone who is trained to dive or swim in a military capacity often in combat A diving bell, also known as a wet bell, is a cable-suspended airtight chamber open at the bottom like a Moon pool structure that is lowered Underwater [1] The system can be permanently placed on a ship or ocean platform, but is more commonly capable of being moved from one vessel to another by crane. The entire system is managed from a control room (van), where depth, chamber atmosphere and other system parameters are monitored and controlled. The diving bell is the elevator or lift that transfers divers from the system to the work site. Typically, it is mated to the system utilizing a removable clamp and is separated from the system tankage bulkhead by a trunking space, a kind of tunnel, through which the divers transfer to and from the bell. At the completion of work or a mission, the saturation diving team is decompressed gradually back to atmospheric pressure by the slow venting of system pressure, at an average of 15 meters/47 feet per day, traveling 24 hours a day (schedules vary). Thus the process involves only one ascent, thereby mitigating the time-consuming and comparatively risky process of in-water, staged decompression normally associated with non-saturation ("mixed gas diving or sur-D O2") operations. [2]

The divers use surface supplied umbilical diving equipment, utilizing deep diving breathing gas, such as helium and oxygen mixtures, stored in large capacity, high pressure cylinders. Surface supplied diving (also known as Hooka diving refers to divers using equipment supplied with Breathing gas using an umbilical cord Air is the most common and only natural breathing gas. Other artificial gases either pure gases or mixtures of gases are used in breathing equipment and enclosed habitats such A diving cylinder, scuba tank or diving tank is used to store and transport high Pressure Breathing gas as a component of SCUBA (Self-Contained [2] The gas supplies are plumbed to the control room, where they are routed to supply the system components. The bell is fed via a large, multi-part umbilical that supplies breathing gas, electricity, communications and hot water. The bell also is fitted with exterior mounted breathing gas cylinders for emergency use.

While in the water the divers will use a hot water suit to protect against the cold. A diving suit is a garment or device designed to protect a diver from the Underwater environment [4] The hot water comes from boilers on the surface and is pumped down to the diver via the bell's umbilical and then through the divers umbilical.

Saturation diving (or more precisely, long term exposure to high pressure) can potentially cause aseptic bone necrosis, although it is not yet known if all divers are affected or only especially sensitive ones. Avascular necrosis is a disease resulting from the temporary or permanent loss of the Blood supply to the bones The joints are most vulnerable to osteonecrosis. Dysbaric osteonecrosis is a form of Avascular necrosis where the death of a portion of the Bone that is thought to be caused by Nitrogen Embolization [5][6][7] The connection between high-pressure exposure and osteonecrosis is not fully understood.

Increased use of underwater ROVs and AUVs for routine or planned tasks means that saturation dives are becoming less common, though complicated underwater tasks requiring complex manual actions remain the preserve of the deep-sea saturation diver. Remotely operated underwater vehicles (ROVs is the common accepted name for tethered underwater Robots in the offshore industry An autonomous underwater vehicle (AUV is a Robot which travels underwater

For saturation diving in fiction, see The Abyss (1989), or Sphere (1998). The Abyss is a Science fiction film that was written and directed by James Cameron in 1989. Sphere is a 1998 Science fiction / Thriller film, starring Dustin Hoffman, Sharon Stone and Samuel L

See also

References

  1. ^ a b c d (2006) US Navy Diving Manual, 6th revision. Surface supplied diving (also known as Hooka diving refers to divers using equipment supplied with Breathing gas using an umbilical cord A diving chamber or submersible chamber has two main functions as a simpler form of submersible vessel to take divers Underwater Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. United States: US Naval Sea Systems Command. Retrieved on 2008-04-24. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1479 BC - Thutmose III ascends to the throne of Egypt, although power effectively shifts to Hatshepsut (according to  
  2. ^ a b c Beyerstein G (2006). Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. "Commercial Diving: Surface-Mixed Gas, Sur-D-O2, Bell Bounce, Saturation". Proceedings of Advanced Scientific Diving Workshop. Retrieved on 2008-05-05. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 553 - The Second Council of Constantinople begins 1215 - Rebel Barons renounce their allegiance to King John  
  3. ^ Bevan, J. (1999). Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) "Diving bells through the centuries". South Pacific Underwater Medicine Society Journal 29 (1). ISSN 0813-1988. An International Standard Serial Number ( ISSN) is a unique eight-digit number used to identify a print or electronic Periodical publication. OCLC 16986801. The OCLC Online Computer Library Center is according to its website a "nonprofit membership computer library service and research organization dedicated to the public purpose  
  4. ^ Mekjavić B, Golden FS, Eglin M, Tipton MJ (2001). "Thermal status of saturation divers during operational dives in the North Sea". Undersea Hyperb Med 28 (3): 149–55. PMID 12067151.  
  5. ^ Brubakk, A. O. ; T. S. Neuman (2003). Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. Bennett and Elliott's physiology and medicine of diving, 5th Rev ed. . United States: Saunders Ltd. , 800. ISBN 0702025712.  
  6. ^ Coulthard A, Pooley J, Reed J, Walder D (1996). Year 1996 ( MCMXCVI) was a Leap year starting on Monday (link will display full 1996 Gregorian calendar) "Pathophysiology of dysbaric osteonecrosis: a magnetic resonance imaging study". Undersea Hyperb Med 23 (2): 119–20. ISSN 1066-2936. An International Standard Serial Number ( ISSN) is a unique eight-digit number used to identify a print or electronic Periodical publication. PMID 8840481. OCLC 26915585. The OCLC Online Computer Library Center is according to its website a "nonprofit membership computer library service and research organization dedicated to the public purpose  
  7. ^ British Medical Research Council Decompression Sickness Central Registry and Radiological Panel (1981). Year 1981 ( MCMLXXXI) was a Common year starting on Thursday (link displays the 1981 "Aseptic bone necrosis in commercial divers. A report from the Decompression Sickness Central Registry and Radiological Panel". Lancet 2 (8243): 384–8. PMID 6115158.  

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