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A decompression stop is a period of time a diver must spend at a constant depth in shallow water at the end of a dive to safely eliminate absorbed inert gases from the diver's body to avoid decompression sickness. Scuba diving is swimming underwater, or taking part in another activity while using a Scuba set. "Inert gases" is also used in a narrower sense for Noble gases An inert gas is any Gas that is not reactive with elements Decompression sickness (DCS, the diver’s disease, the bends, caisson disease is the name given to a variety of symptoms suffered by a person [1] The practice of making decompression stops is called staged decompression[2][3], as opposed to continuous decompression. [4][5]

Doing a stop

The diver uses decompression tables[6] or dive computers to find, for his planned dive profile and breathing gas, if decompression stops are needed, and if so, the depths and durations of the stops. Dive Tables, Decompression Tables or Tables are printed cards or booklets that allow divers to determine for a particular dive profile and breathing gas A dive computer or decompression meter is a device used by a scuba diver to measure the time and depth of a dive so that a safe ascent rate can be calculated 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 "no stop" dive is a dive that needs no decompression stops during the ascent. [1]

Shorter and shallower decompression dives may only need one single short shallow decompression stop, for example 5 minutes at 3 metres (10 ft). Longer and deeper dives often need a series of decompression stops, each stop being longer but shallower than the previous stop. As a precaution against any unnoticed dive computer malfunction, diver error or physiological predisposition to decompression sickness, many divers do an extra "safety stop"[7] in addition to those ordered by their dive computer or tables. Physiology (from Greek grc φύσις physis, "nature origin" and grc -λογία -logia) is the study of the mechanical physical A safety stop is typically 1 to 5 minutes at 3 to 6 metres (10 to 20 ft). They are even done during no-stop dives.

In addition to stops, the diver must not exceed a safe ascent rate during the whole of the ascent from depth. Normally the time to ascend the shallowest 20 feet (6 metres) to the surface will take at least 1 minute. Typically with tables, the maximum ascent rate is 30 feet (10 metres) per minute when deeper than 20 feet (6 metres). Some dive computers have variable maximum ascent rates, depending on depth.

Mechanism

During the stop, the "microbubbles" present after every dive leave the diver's body safely through the lungs. lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive If they are not given enough time to leave safely or more bubbles are created than can be eliminated naturally, the bubbles grow in size and number causing the symptoms and injuries of decompression sickness. [8]

When diving with nitrogen based breathing gases, decompression stops are typically carried out in the 10 to 65 feet (3 to 20 metres) depth range. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 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 With helium based breathing gases, the stop depth is typically between 65 and 130 feet (20 and 40 metres). Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical High partial pressures of oxygen are commonly used in decompression gases to use the effect of the oxygen window. In diving the oxygen window is the difference between the Partial pressure of Oxygen (ppO2 in arterial blood and the ppO2 in body tissues

The length of "surface interval" between dives is also very important for decompression. It typically takes from 16 to 24 hours for the body to return to its normal atmospheric levels of inert gas saturation after a dive. The surface interval can be thought of as the last decompression stop of a dive. [9]

Breathing gas type

Only divers breathing gas at high pressure, such as when using scuba, may need to do decompression stops. 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 A scuba set is an independent breathing set that provides a scuba diver with the Breathing gas necessary to breathe underwater during Scuba diving. A diver who breathes gas at atmospheric pressure, such as in free-diving, snorkeling, or when using an atmospheric diving suit, does not need to do decompression stops. Free diving is any of various aquatic activities that share the practice of breath-holding Underwater diving. Snorkeling ( British spelling: snorkelling) is the practice of Swimming at the surface of a body of water while equipped with a Diving mask, a Atmospheric Diving Suit or ADS is a small one-man articulated Submersible of Anthropomorphic form which resembles a suit of armour with elaborate pressure However, it is possible to get taravana from repetitive deep free-diving with short surface intervals. Taravana is a disease among Polynesian island natives who habitually dive deep without breathing apparatus many times in close succession usually for food or Free diving is any of various aquatic activities that share the practice of breath-holding Underwater diving. [10]

Deep stops

A "Pyle stop" is an additional short deep-water stop, which is increasingly used in deep diving. The meaning of the term deep diving is a form of Technical diving. Typically, a Pyle stop is 2 minutes long and at the depth where the pressure change halves on an ascent from the bottom to a shallow water decompression stop. For example, on an ascent from a maximum depth of 196 feet (60 metres) at 100 psi (7 bar) to a decompression stop at 65 feet (20 metres) at 40 psi (3 bar), the Pyle stop would take place at the halfway pressure, which is 70 psi (5 bar) at 130 feet (40 metres). [11]

Missed stops

A diver missing a decompression stop risks developing decompression sickness. The longer the stops missed, the greater the risk. The usual causes for missing stops are: not having enough breathing gas to complete the stops, or accidentally losing control of buoyancy. 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 An aim of most basic diver training is to prevent these two faults. Diver training is the process of developing skills and building experience in the use of Diving equipment and techniques so that the diver is able to dive safely and There are less predictable causes of missing decompression stops. Diving suit failure in cold water forces the diver to choose between hypothermia and decompression sickness. A diving suit is a garment or device designed to protect a diver from the Underwater environment Hypothermia is a condition in which an organism's temperature drops below that required for normal Metabolism and bodily functions Decompression sickness (DCS, the diver’s disease, the bends, caisson disease is the name given to a variety of symptoms suffered by a person Diver injury or marine animal attack also limit the duration of stops the diver is willing to carry out.

Technical diving education organizations define special procedures to be done if decompression stops are missed. Technical diving (sometimes referred to a Tec diving) is a form of Scuba diving that exceeds the scope of Recreational diving (although the vast majority These procedures may need repeating one or several stops.

Equipment

There are several pieces of safety equipment used to help divers carry out decompression stops. A diving shot, a surface marker buoy or a decompression buoy can be used to mark the underwater positions and act as a buoyancy control aid in low visibility or currents. A diving shot is an item of Diving equipment consisting of a Weight, a line and a Buoy. Surface Marker Buoy (standard A Surface Marker Buoy, SMB or simply a blob is an inflatable Buoy used by SCUBA divers, Surface Marker Buoy (standard A Surface Marker Buoy, SMB or simply a blob is an inflatable Buoy used by SCUBA divers, A decompression trapeze is useful for comfortably carrying out long stops. A decompression trapeze is a device used in Recreational diving and Technical diving to make Decompression stops more comfortable and more secure and provide A Jonline may be used to fasten a diver to an anchor line or rope during a Decompression stop

Decompression may be shortened (or accelerated) by breathing an oxygen-rich "deco gas" such as a nitrox with 50% or more oxygen. A Jonline is a short line used by SCUBA-divers to fasten themselves to something Nitrox refers to any gas mixture composed (excluding trace gases of nitrogen and oxygen this includes normal Air which is approximately 78% Nitrogen This decompression gas is sometimes carried in small diving cylinders called "pony cylinders" or in larger side-slung cylinders. 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

References

  1. ^ a b Brubakk, A. O. ; T. S. Neuman (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed. . United States: Saunders Ltd. , 800. ISBN 0702025712.  
  2. ^ Boycott, A. E. ; J. C. C. Damant, J. S. Haldane. (1908). Year 1908 ( MCMVIII) was a Leap year starting on Wednesday (link will display the full calendar of the Gregorian calendar (or a Leap year "Prevention of compressed air illness". J. Hygiene 8: 342-425.  
  3. ^ Bühlmann, A. A. (1984). Decompression-Decompression Sickness. Berlin New York: Springer-Verlag. ISBN 0387133089.  
  4. ^ Bert, P. (originally published 1878). Year 1878 ( MDCCCLXXVIII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common "Barometric Pressure: researches in experimental physiology". Translated by: Hitchcock MA and Hitchcock FA. College Book Company; 1943.  
  5. ^ Sport Diving, British Sub Aqua Club, ISBN0091638313, page 110
  6. ^ (2006) US Navy Diving Manual, 6th revision. 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  
  7. ^ Uguccioni, DM (1984). Doppler Detection of Silent Venous Gas Emboli in Non-Decompression Diving Involving Safety Stops. Wilmington, NC: University of North Carolina at Wilmington. Retrieved on 2008-04-25. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1607 - Eighty Years' War: The Dutch fleet destroys the anchored Spanish fleet at Gibraltar.  
  8. ^ Sport Diving, British Sub Aqua Club, ISBN0091638313, page 104
  9. ^ BSAC '88 Decompression Tables Levels 1 to 4
  10. ^ Wong, R. M. (1999). Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) "Taravana revisited: Decompression illness after breath-hold diving". South Pacific Underwater Medicine Society journal 29 (3). 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  
  11. ^ Deep Decompression Stops
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