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Rebreathers
A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's breathing, exhaled breath to permit the rebreathing (recycling) of the substantial 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, while also eliminating the bubbles otherwise produced by an open circuit system. The latter advantage over other systems is useful for covert military operations by frogmen, as well as for undisturbed observation of underwater wildlife. A rebreather is generally understood to be a portable apparatus 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. Rebreather technology may be used where breathing ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scuba Set
A scuba set, originally just scuba, is any breathing apparatus that is entirely carried by an underwater diving, 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 that is required for providing breathing gas to the diver, general usage includes the harness or rigging 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 (diving), buoyancy compensator and instruments mounted in a combined housing with the pressure gauge. In the looser sense, scuba set has been used to refer to all the 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 r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-contained Underwater Breathing Apparatus
A scuba set, originally just scuba, is any breathing apparatus that is entirely carried 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 that is required for providing breathing gas to the diver, general usage includes the harness or rigging 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. In the looser sense, scuba set has been used to refer to all the 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 profes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypercapnia
Hypercapnia (from the Greek ''hyper'', "above" or "too much" and ''kapnos'', "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous product of the body's metabolism and is normally expelled through the lungs. Carbon dioxide may accumulate in any condition that causes hypoventilation, a reduction of alveolar ventilation (the clearance of air from the small sacs of the lung where gas exchange takes place) as well as resulting from inhalation of CO2. Inability of the lungs to clear carbon dioxide, or inhalation of elevated levels of CO2, leads to respiratory acidosis. Eventually the body compensates for the raised acidity by retaining alkali in the kidneys, a process known as "metabolic compensation". Acute hypercapnia is called acute hypercapnic respiratory failure (AHRF) and is a medical emergency as it generally occurs in the context of acute illness. Chronic hypercapn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decompression Status
To prevent or minimize decompression sickness, Underwater diving, divers must properly plan and monitor Decompression (diving), decompression. Divers follow a decompression model to safely allow the release of excess inert gases dissolved in their body tissues, which accumulated as a result of breathing at ambient pressures greater than surface atmospheric pressure. Decompression models take into account variables such as depth and time of dive, breathing gasses, altitude, and equipment to develop appropriate procedures for safe ascent. Decompression may be continuous or staged, where the ascent is interrupted by stops at regular depth intervals, but the entire ascent is part of the decompression, and ascent rate can be critical to harmless elimination of inert gas. What is commonly known as no-decompression diving, or more accurately no-stop decompression, relies on limiting ascent rate for avoidance of excessive bubble formation. Staged decompression may include deep stops de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frogmen
A frogman is someone who is trained in scuba diving or swimming underwater. The term often applies more to professional rather than recreational divers, especially those working in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, combatant diver, or combat swimmer. The word ''frogman'' first arose in the stage name the "Fearless Frogman" of Paul Boyton in the 1870s and later was claimed by John Spence, an enlisted member of the U.S. Navy and member of the OSS Maritime Unit, to have been applied to him while he was training in a green waterproof suit. The term ''frogman'' is occasionally used to refer to a civilian scuba diver, such as in a police diving role. In the United Kingdom, police divers have often been called "police frogmen". Some countries' tactical diver organizations include a translation of the word ''frogman'' in their official names, e.g., Denmark ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Suit
A space suit (or spacesuit) is an environmental suit used for protection from the harsh environment of outer space, mainly from its vacuum as a highly specialized pressure suit, but also its temperature extremes, as well as radiation and micrometeoroids. Basic space suits are worn as a safety precaution inside spacecrafts in case of loss of cabin pressure. For extravehicular activity (EVA) more complex space suits are worn, featuring a portable life support system. Pressure suits are in general needed at low pressure environments above the Armstrong limit, at around above Earth. Space suits augment pressure suits with complex system of equipment and environmental systems designed to keep the wearer comfortable, and to minimize the effort required to bend the limbs, resisting a soft pressure garment's natural tendency to stiffen against the vacuum. A self-contained oxygen supply and environmental control system is frequently employed to allow complete freedom of movement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Davis Submerged Escape Apparatus
The Davis Submerged Escape Apparatus (also referred to as DSEA), was an early type of oxygen rebreather invented in 1910 by Robert Davis (inventor), Sir Robert Davis, head of Siebe Gorman, 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 Underwater diving, diving, being a handy shallow water diving apparatus with a thirty-minute endurance, and as an SCBA, industrial breathing set. Design The DSEA rig chiefly addressed the problem of Hypoxia (medical), anoxia threatening a person ascending through water, by providing oxygen; and the associated risk of Barotrauma#Pressure differences while diving, lung over-pressure injury as underwater pressure reduces with reducing depth, which it addressed by managing oxygen pressures. It also provided assistance with buoyancy, both in the ascent and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breathing
Breathing (spiration or ventilation) is the rhythmical process of moving air into ( inhalation) and out of ( exhalation) the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen. All aerobic creatures need oxygen for cellular respiration, which extracts energy from the reaction of oxygen with molecules derived from food and produces carbon dioxide as a waste product. Breathing, or external respiration, brings air into the lungs where gas exchange takes place in the alveoli through diffusion. The body's circulatory system transports these gases to and from the cells, where cellular respiration takes place. The breathing of all vertebrates with lungs consists of repetitive cycles of inhalation and exhalation through a highly branched system of tubes or airways which lead from the nose to the alveoli. The number of respiratory cycles per minute is the breathing or respiratory rate, and is one of the fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Reclaim System
Saturation diving is an ambient pressure diving technique which allows a diver to remain at working depth for extended periods during which the body tissues become saturated with metabolically inert gas from the breathing gas mixture. Once saturated, the time required for decompression to surface pressure will not increase with longer exposure. The diver undergoes a single decompression at the end of the exposure of several days to weeks duration. The ratio of productive working time at depth to unproductive decompression time is thereby increased, and the health risk to the diver incurred by decompression is minimised. When a diver breathes pressurized gas, metabolically inert gases are needed in the mixture to dilute oxygen to non-toxic levels. These gases dissolve into the body's tissues, but if they come out of solution too quickly during decompression, they form bubbles in the tissues which can cause decompression sickness ("the bends"), a harmful and potentially fatal con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boyle's Law
Boyle's law, also referred to as the Boyle–Mariotte law or Mariotte's law (especially in France), is an empirical gas laws, gas law that describes the relationship between pressure and volume of a confined gas. Boyle's law has been stated as: The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of substance, amount of gas remain unchanged within a closed system.Levine (1978) p. 12 gives the original definition. Mathematically, Boyle's law can be stated as: or where is the pressure of the gas, is the volume of the gas, and is a Constant (mathematics), constant for a particular temperature and amount of gas. Boyle's law states that when the temperature of a given mass of confined gas is constant, the product of its pressure and volume is also constant. When comparing the same substance under two different sets of conditions, the law can be expressed as: P_1 V_1 = P_2 V_2. showi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glossary Of Underwater Diving Terminology
This is a glossary of technical terms, jargon, diver slang and acronyms used in underwater diving Underwater diving, as a human activity, is the practice of descending below the water's surface to interact with the environment. It is also often referred to as diving (other), diving, an ambiguous term with several possible meani .... The definitions listed are in the context of underwater diving. There may be other meanings in other contexts. Underwater diving can be described as a human activity – intentional, purposive, conscious and subjectively meaningful sequence of actions. Underwater diving is practiced as part of an occupation, or for recreation, where the practitioner submerges below the surface of the water or other liquid for a period which may range between seconds to the order of a day at a time, either exposed to the ambient pressure or isolated by a pressure resistant suit, to interact with the underwater environment for pleasure, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Sea Level
Standard sea-level conditions (SSL), also known as sea-level standard (SLS), defines a set of atmospheric conditions for physical calculations. The term "standard sea level" is used to indicate that values of properties are to be taken to be the same as those standard at sea level, and is done to define values for use in general calculations. Atmospheric properties At SSL some atmospheric properties are: * Pressure, ''P'' = 101.325 kPa ⇔ 2116.2 lbf/ ft2 ⇔ 14.696 lbf/ in2 ⇔ 760 mmHg ⇔ 29.92 inHg * Density, \rho = 1.225 kg/m3 ⇔ 0.002377 slug/ft3 * Temperature, ''T'' = 15 °C ⇔ 59 °F ⇔ 288.15 K ⇔ 518.67 °R * Gas constant of air, ''R''air = 287.057 J/(kg·K) ⇔ 1716.59 ft·lb/sl·°R) * Specific Weight, \gamma = 12.014 N/ m3 ⇔ 0.07647 lbf/ ft3 * Dynamic viscosity, \mu = 1.789×10−5 Pa·s ⇔ 3.737×10−7 slug/(s·ft) * Acceleration of gravity, ''g0'' = 9.807 m/s2 ⇔ 32.174 ft/s2 See also * Sea level * Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
