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Recreational Nitrox
Nitrox refers to any gas mixture composed (excepting trace gases) of nitrogen and oxygen. It is usually used for mixtures that contain less than 78% nitrogen by volume. In the usual application, underwater diving, nitrox is normally distinguished from air and handled differently. The most common use of nitrox mixtures containing oxygen in higher proportions than atmospheric air is in scuba diving, where the reduced partial pressure of nitrogen is advantageous in reducing nitrogen uptake in the body's tissues, thereby extending the practicable underwater dive time by reducing the decompression requirement, or reducing the risk of decompression sickness (also known as ''the bends''). The two most common recreational diving nitrox mixes are 32% and 36% oxygen, which have maximum operating depths of about 110 feet (34 meters) and 95 feet (29 meters) respectively. Nitrox is used to a lesser extent in surface-supplied diving, as these advantages are reduced by the more complex logisti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breathing Gas
A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats. Oxygen is the essential component for any breathing gas. Breathing gases for hyperbaric use have been developed to improve on the performance of ordinary air by reducing the risk of decompression sickness, reducing the duration of decompression, reducing nitrogen narcosis or reducing work of breathing and allowing safer deep diving. Description A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas. Other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats such as scuba equipment, surface supplied diving equipment, recompression chambers, high-altitude mountaineering, high-flying aircraf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrox
Nitrox refers to any gas mixture composed (excepting trace gases) of nitrogen and oxygen. It is usually used for mixtures that contain less than 78% nitrogen by volume. In the usual application, underwater diving, nitrox is normally distinguished from air and handled differently. The most common use of nitrox mixtures containing oxygen in higher proportions than atmospheric air is in scuba diving, where the reduced partial pressure of nitrogen is advantageous in reducing nitrogen uptake in the body's tissues, thereby extending the practicable underwater dive time by reducing the decompression requirement, or reducing the risk of decompression sickness (also known as ''the bends''). The two most common recreational diving nitrox mixes are 32% and 36% oxygen, which have maximum operating depths of about 110 feet (34 meters) and 95 feet (29 meters) respectively. Nitrox is used to a lesser extent in surface-supplied diving, as these advantages are reduced by the more complex logi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Critical Flicker Fusion Frequency
The flicker fusion threshold, also known as critical flicker frequency or flicker fusion rate, is the frequency at which a flickering light appears steady to the average human observer. It is a concept studied in vision science, more specifically in the psychophysics of visual perception. A traditional term for "flicker fusion" is "persistence of vision", but this has also been used to describe positive afterimages or motion blur. Although flicker can be detected for many waveforms representing time-variant fluctuations of intensity, it is conventionally, and most easily, studied in terms of sinusoidal modulation of intensity. There are seven parameters that determine the ability to detect the flicker: # the frequency of the modulation; # the amplitude or depth of the modulation (i.e., what is the maximum percent decrease in the illumination intensity from its peak value); # the average (or maximum—these can be inter-converted if modulation depth is known) illumination intens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acronym
An acronym is a type of abbreviation consisting of a phrase whose only pronounced elements are the initial letters or initial sounds of words inside that phrase. Acronyms are often spelled with the initial Letter (alphabet), letter of each word in all caps with no punctuation. For some, an initialism or alphabetism connotes this general meaning, and an ''acronym'' is a subset with a narrower definition; an acronym is pronounced as a word rather than as a sequence of letters. In this sense, ''NASA'' () is an acronym, but ''United States, USA'' () is not. The broader sense of ''acronym'', ignoring pronunciation, is its original meaning and in common use. . Dictionary and style-guide editors dispute whether the term ''acronym'' can be legitimately applied to abbreviations which are not pronounced as words, and they do not agree on acronym space (punctuation), spacing, letter case, casing, and punctuation. The phrase that the acronym stands for is called its . The of an acron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technical Diving International
Technical Diving International (TDI) claims to be the largest technical diving certification agency in the world, and one of the first agencies to offer mixed gas and rebreather training. TDI specializes in more advanced Scuba diving techniques, particularly diving with rebreathers and use of breathing gases such as trimix and heliox. TDI provides courses and certification for divers and for instructors. TDI history TDI was founded in 1992 by Mitch Skaggs, Bret Gilliam and David Sipperly after a split away from International Association of Nitrox and Technical Divers (IANTD) in 1993. The agency aimed to provide training materials and education for specialized diving situations. Some courses offered by TDI include open circuit courses such as diving with Nitrox as well as Rebreather courses. They also provide training for overhead environments like caves and wrecks, mixed gas training and were one of the first diving agencies to create a comprehensive insurance plan fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen Sensor
An oxygen sensor is an electronic component that detects the concentration of oxygen molecules in the air or a gas matrix such as in a combustion engine exhaust gas. For automotive applications, an oxygen sensor is referred to as a lambda sensor, where lambda refers to the air–fuel equivalence ratio, usually denoted by λ). It was developed by Robert Bosch GmbH during the late 1960s under the supervision of Günter Bauman. The original sensing element is made with a thimble-shaped zirconia ceramic coated on both the exhaust and reference sides with a thin layer of platinum and comes in both heated and unheated forms. The planar-style sensor entered the market in 1990 and significantly reduced the mass of the ceramic sensing element, as well as incorporating the heater within the ceramic structure. This resulted in a sensor that started sooner and responded faster. The most common application is to measure the exhaust-gas concentration of oxygen for internal combustion engine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Blending For Scuba Diving
Gas blending for scuba diving (or gas mixing) is the filling of diving cylinders with non-air breathing gases such as nitrox, Trimix (breathing gas), trimix and heliox. Use of these gases is generally intended to improve overall safety of the planned dive, by reducing the risk of decompression sickness and/or nitrogen narcosis, and may improve Work of breathing, ease of breathing. Filling cylinders with a mixture of gases has dangers for both the filler and the diver. During filling there is a risk of fire due to use of oxygen and a risk of explosion due to the use of high-pressure gases. The composition of the mix must be safe for the depth and duration of the planned dive. If the concentration of oxygen is too lean the diver may lose consciousness due to Hypoxia (medical), hypoxia and if it is too rich the diver may suffer oxygen toxicity. The concentration of inert gases, such as nitrogen and helium, are planned and checked to avoid nitrogen narcosis and decompression sicknes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy
Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus, the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the Displacement (fluid), displaced fluid. For this reason, an object with average density greater than the surrounding fluid tends to sink because its weight is greater than the weight of the fluid it displaces. If the objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Professional Diving
Professional diving is underwater diving where the divers are paid for their work. Occupational diving has a similar meaning and applications. The diving procedures, procedures are often regulated by legislation and codes of practice as it is an inherently occupational safety and health, hazardous occupation and the diver works as a member of a diving team, team. Due to the dangerous nature of some professional diving operations, specialized equipment such as an on-site hyperbaric chamber and diver-to-surface communication system is often required by law, and the mode of diving for some applications may be regulated. There are several branches of professional diving, the best known of which is probably commercial diving and its specialised applications, offshore diving, inshore civil engineering diving, marine salvage diving, hazmat diving, and ships husbandry diving. There are also applications in Scientific diving, scientific research, marine archaeology, fishing and aquacultur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maximum Operating Depth
In underwater diving activities such as saturation diving, technical diving and nitrox diving, the maximum operating depth (MOD) of a breathing gas is the depth below which the partial pressure of oxygen (pO2) of the gas mix exceeds an acceptable limit. This limit is based on risk of central nervous system oxygen toxicity, and is somewhat arbitrary, and varies depending on the diver training agency or Code of Practice, the level of underwater exertion expected and the planned duration of the dive, but is normally in the range of 1.2 to 1.6 bar. The MOD is significant when planning dives using gases such as heliox, nitrox and trimix because the proportion of oxygen in the mix determines a maximum depth for breathing that gas at an acceptable risk. There is a risk of acute oxygen toxicity if the MOD is exceeded. The tables below show MODs for a selection of oxygen mixes. Atmospheric air contains approximately 21% oxygen, and has an MOD calculated by the same method. Safe limit o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recreational Diving
Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure and are considered to be " fun". Etymology The term ''recreation'' appears to have been used in English first in the late 14th century, first in the sense of "refreshment or curing of a sick person", and derived turn from Latin (''re'': "again", ''creare'': "to create, bring forth, beget"). Prerequisites to leisure People spend their time on activities of daily living, work, sleep, social duties and leisure, the latter time being free from prior commitments to physiologic or social needs, a prerequisite of recreation. Leisure has increased with increased longevity and, for many, with decreased hours spent for physical and economic survival, yet others argue that time pressure has increased for modern people, as they are committed to to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
