1.
Pressure vessel
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A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure. The pressure differential is dangerous, and fatal accidents have occurred in the history of pressure vessel development, consequently, pressure vessel design, manufacture, and operation are regulated by engineering authorities backed by legislation. The preferred test is hydrostatic testing because its a much safer method of testing as it much less energy if fracture were to occur. Today vessels in the USA require BPVC stamping but the BPVC is not just a domestic code, there are, however, other official codes in some countries, Japan, Australia, Canada, Britain, and Europe have their own codes. Regardless of the nearly all recognize the inherent potential hazards of pressure vessels. Pressure vessels can theoretically be almost any shape, but shapes made of sections of spheres, cylinders, a common design is a cylinder with end caps called heads. Head shapes are frequently either hemispherical or dished, more complicated shapes have historically been much harder to analyze for safe operation and are usually far more difficult to construct. Theoretically, a pressure vessel has approximately twice the strength of a cylindrical pressure vessel with the same wall thickness. However, a shape is difficult to manufacture, and therefore more expensive. Smaller pressure vessels are assembled from a pipe and two covers, many pressure vessels are made of steel. To manufacture a cylindrical or spherical pressure vessel, rolled and possibly forged parts would have to be welded together, some mechanical properties of steel, achieved by rolling or forging, could be adversely affected by welding, unless special precautions are taken. In addition to adequate strength, current standards dictate the use of steel with a high impact resistance. In applications where carbon steel would suffer corrosion, special corrosion resistant material should also be used, some pressure vessels are made of composite materials, such as filament wound composite using carbon fibre held in place with a polymer. Due to the high tensile strength of carbon fibre these vessels can be very light. The composite material may be wound around a metal liner, forming a composite overwrapped pressure vessel, other very common materials include polymers such as PET in carbonated beverage containers and copper in plumbing. Pressure vessels may be lined with metals, ceramics, or polymers to prevent leaking. This liner may also carry a significant portion of the pressure load, Pressure Vessels may also be constructed from concrete or other materials which are weak in tension. Cabling, wrapped around the vessel or within the wall or the vessel itself, a leakproof steel thin membrane lines the internal wall of the vessel
2.
Pipeline transport
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Pipeline transport is the transportation of goods or material through a pipe. The latest data, in 2014, gives a total of less than 2,175,000 miles of pipeline in 120 countries of the world. The United States had 65%, Russia had 8%, and Canada had 3%, Pipeline and Gas Journal’s worldwide survey figures indicate that 118,623 miles of pipelines are planned and under construction. Of these,88,976 miles represent projects in the planning, Liquids and gases are transported in pipelines and any chemically stable substance can be sent through a pipeline. Pipelines exist for the transport of crude and refined petroleum, fuels - such as oil, natural gas and biofuels - and other fluids including sewage, slurry, water, pneumatic tubes using compressed air can be used to transport solid capsules. Oil pipelines are made from steel or plastic tubes which are usually buried, the oil is moved through the pipelines by pump stations along the pipeline. Natural gas are lightly pressurised into liquids known as Natural Gas Liquids, Natural gas pipelines are constructed of carbon steel. Highly toxic ammonia is theoretically the most dangerous substance to be transported through long-distance pipelines, hydrogen pipeline transport is the transportation of hydrogen through a pipe. District heating or teleheating systems use a network of insulated pipes which transport heated water, pipelines conveying flammable or explosive material, such as natural gas or oil, pose special safety concerns and there have been various accidents. Pipelines can be the target of vandalism, sabotage, or even terrorist attacks, in war, pipelines are often the target of military attacks. It is uncertain when the first crude oil pipeline was built, pipelines are generally the most economical way to transport large quantities of oil, refined oil products or natural gas over land. Natural gas are lightly pressurized into liquids knows as Natural Gas Liquids, small NGL processing facilities can be located in oil fields so the butane and propane liquid under light pressure of 125 pounds per square inch, can be shipped by rail, truck or pipeline. Propane can be used as a fuel in oil fields to heat various facilities used by the oil drillers or equipment and trucks used in the oil patch. EG, Propane will convert from a gas to a liquid under pressure,100 psi, give or take depending on temperature. Pipelines and rail cars use about double that pressure to pump at 250 psi, the distance to ship propane to markets is much shorter, as thousands of natural-gas processing plants are located in or near oil fields. Compared to shipping by railroad, pipelines have lower cost per unit, pipelines are preferable to transportation by truck for a number of reasons. Employment on completed pipelines represents only 1% of that of the trucking industry and this allows the Bakken Basin and Three Forks oil producers to get higher negotiated prices for their oil because they will not be restricted to just one wholesale market in the US. The distance from the biggest oil patch in North Dakota, is Williston, North Dakota, only about 85 miles or 137 kilometers to the Canada–US border, mutual funds and joint ventures are big investors in new oil and gas pipelines
3.
Plumbing
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Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, heating and cooling, waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes, in the developed world, plumbing infrastructure is critical to public health and sanitation. Boilermakers and pipefitters are not plumbers, although they work with piping as part of their trade, standardized earthen plumbing pipes with broad flanges making use of asphalt for preventing leakages appeared in the urban settlements of the Indus Valley Civilization by 2700 B. C. The Romans used lead pipe inscriptions to prevent water theft, Plumbing reached its early apex in ancient Rome, which saw the introduction of expansive systems of aqueducts, tile wastewater removal, and widespread use of lead pipes. With the Fall of Rome both water supply and sanitation stagnated—or regressed—for well over 1,000 years, improvement was very slow, with little effective progress made until the growth of modern densely populated cities in the 1800s. During this period, public authorities began pressing for better waste disposal systems to be installed. Earlier, the disposal system had merely consisted of collecting waste. Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches, most large cities today pipe solid wastes to sewage treatment plants in order to separate and partially purify the water, before emptying into streams or other bodies of water. For potable water use, galvanized iron piping was commonplace in the United States from the late 1800s until around 1960, after that period, copper piping took over, first soft copper with flared fittings, then with rigid copper tubing utilizing soldered fittings. The use of lead for potable water declined sharply after World War II because of increased awareness of the dangers of lead poisoning, at this time, copper piping was introduced as a better and safer alternative to lead pipes. e. Heating and cooling systems utilizing water to transport thermal energy, as in district heating systems, a water pipe is a pipe or tube, frequently made of plastic or metal, that carries pressurized and treated fresh water to a building, as well as inside the building. For many centuries, lead was the material for water pipes. This was a source of lead-related health problems in the years before the hazards of ingesting lead were fully understood, among these were stillbirths. Lead water pipes were still used in the early 20th century. In addition, lead-tin alloy solder was commonly used to join copper pipes, despite the Romans common use of lead pipes, their aqueducts rarely poisoned people. Unlike other parts of the world where lead pipes cause poisoning, what often causes confusion is the large amount of evidence of widespread lead poisoning, particularly amongst those who would have had easy access to piped water. This was a result of lead being used in cookware and as an additive to processed food and drink
4.
Boiler
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A boiler is a closed vessel in which water or other fluid is heated. The fluid does not necessarily boil, the heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation, cooking, and sanitation. The pressure vessel of a boiler is usually made of steel, stainless steel, especially of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion cracking. In live steam models, copper or brass is used because it is more easily fabricated in smaller size boilers. For much of the Victorian age of steam, the material used for boilermaking was the highest grade of wrought iron. In the 20th century, design practice instead moved towards the use of steel, which is stronger and cheaper, with welded construction, which is quicker and requires less labour. It should be noted, however, that wrought iron boilers corrode far slower than their steel counterparts. This makes the longevity of older wrought-iron boilers far superior to those of welded steel boilers, cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are usually termed boilers in some countries, their purpose is usually to produce hot water, not steam, the brittleness of cast iron makes it impractical for high-pressure steam boilers. The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, electric steam boilers use resistance- or immersion-type heating elements. Nuclear fission is used as a heat source for generating steam, either directly or, in most cases. Heat recovery steam generators use the heat rejected from other such as gas turbine. 18th century Haycock boilers generally produced and stored large volumes of very low-pressure steam and these could burn wood or most often, coal. Flued boiler with one or two large flues—an early type or forerunner of fire-tube boiler, fire-tube boiler, Here, water partially fills a boiler barrel with a small volume left above to accommodate the steam. This is the type of boiler used in nearly all steam locomotives, the heat source is inside a furnace or firebox that has to be kept permanently surrounded by the water in order to maintain the temperature of the heating surface below the boiling point. Fire-tube boilers usually have a low rate of steam production. Fire-tube boilers mostly burn solid fuels, but are adaptable to those of the liquid or gas variety. Water-tube boiler, In this type, tubes filled with water are arranged inside a furnace in a number of possible configurations and this type generally gives high steam production rates, but less storage capacity than the above
5.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
6.
Red
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Red is the color at the longer-wavelengths end of the spectrum of visible light next to orange, at the opposite end from violet. Red color has a predominant light wavelength of roughly 620–740 nanometers, light with a longer wavelength than red but shorter than terahertz radiation and microwave is called infrared. Red is one of the secondary colors, resulting from the combination of yellow. Traditionally, it was viewed as a primary colour, along with yellow and blue, in the RYB color space and traditional color wheel formerly used by painters. Reds can vary in shade from light pink to very dark maroon or burgundy. Red is the color of cyan. In nature, the red color of blood comes from hemoglobin, the red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It also causes the red color of the planet Mars, the color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced. One to two percent of the population has red hair, the color is produced by high levels of the reddish pigment pheomelanin. Since red is the color of blood, it has historically been associated with sacrifice, danger, modern surveys in the United States and Europe show red is also the color most commonly associated with heat, activity, passion, sexuality, anger, love and joy. In China, India and many other Asian countries it is the color of symbolizing happiness, since the 19th century, red has also been associated with socialism and communism. The word red is derived from the Old English rēad, the word can be further traced to the Proto-Germanic rauthaz and the Proto-Indo European root rewdʰ-. In Sanskrit, the word means red or blood. In the Akkadian language of Ancient Mesopotamia and in the modern Inuit language of Inuit, the words for colored in Latin and Spanish both also mean red. In Portuguese the word for red is vermelho, which comes from Latin vermiculus, in the Russian language, the word for red, Кра́сный, comes from the same old Slavic root as the words for beautiful—красивый and excellent—прекрасный. Thus Red Square in Moscow, named long before the Russian Revolution, in heraldry, the word gules is used for red. Red can vary in hue from orange-red to violet-red, and for each hue there is a variety of shades and tints. Red hematite powder was found scattered around the remains at a grave site in a Zhoukoudian cave complex near Beijing
7.
Fluorescence
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Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence, in most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. Fluorescent materials cease to glow immediately when the radiation source stops, unlike phosphorescence, Fluorescence also occurs frequently in nature in some minerals and in various biological states in many branches of the animal kingdom. An early observation of fluorescence was described in 1560 by Bernardino de Sahagún and it was derived from the wood of two tree species, Pterocarpus indicus and Eysenhardtia polystachya. The chemical compound responsible for this fluorescence is matlaline, which is the product of one of the flavonoids found in this wood. The name was derived from the fluorite, some examples of which contain traces of divalent europium. In a key experiment he used a prism to isolate ultraviolet radiation from sunlight, the specific frequencies of exciting and emitted light are dependent on the particular system. S0 is called the state of the fluorophore, and S1 is its first excited singlet state. A molecule in S1 can relax by various competing pathways and it can undergo non-radiative relaxation in which the excitation energy is dissipated as heat to the solvent. Excited organic molecules can also relax via conversion to a triplet state, relaxation from S1 can also occur through interaction with a second molecule through fluorescence quenching. Molecular oxygen is an extremely efficient quencher of fluorescence just because of its unusual triplet ground state, in most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation, this phenomenon is known as the Stokes shift. The emitted radiation may also be of the wavelength as the absorbed radiation. Molecules that are excited through light absorption or via a different process can transfer energy to a second sensitized molecule, the fluorescence quantum yield gives the efficiency of the fluorescence process. It is defined as the ratio of the number of photons emitted to the number of photons absorbed, Φ = Number of photons emitted Number of photons absorbed The maximum fluorescence quantum yield is 1.0, each photon absorbed results in a photon emitted. Compounds with quantum yields of 0.10 are still considered quite fluorescent, thus, if the rate of any pathway changes, both the excited state lifetime and the fluorescence quantum yield will be affected. Fluorescence quantum yields are measured by comparison to a standard, the quinine salt quinine sulfate in a sulfuric acid solution is a common fluorescence standard. The fluorescence lifetime refers to the time the molecule stays in its excited state before emitting a photon. This is an instance of exponential decay, various radiative and non-radiative processes can de-populate the excited state
8.
Dye
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A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber. Both dyes and pigments are colored because they absorb some wavelengths of light more than others, in contrast to dyes, pigments are insoluble and have no affinity for the substrate. Some dyes can be precipitated with a salt to produce a lake pigment. The majority of natural dyes are from plant sources, roots, berries, bark, leaves, and wood, fungi, textile dyeing dates back to the Neolithic period. Throughout history, people have dyed their textiles using common, locally available materials, scarce dyestuffs that produced brilliant and permanent colors such as the natural invertebrate dyes Tyrian purple and crimson kermes were highly prized luxury items in the ancient and medieval world. Plant-based dyes such as woad, indigo, saffron, and madder were raised commercially and were important trade goods in the economies of Asia, across Asia and Africa, patterned fabrics were produced using resist dyeing techniques to control the absorption of color in piece-dyed cloth. Dyes from the New World such as cochineal and logwood were brought to Europe by the Spanish treasure fleets, dyed flax fibers have been found in the Republic of Georgia in a prehistoric cave dated to 36,000 BP. Archaeological evidence shows that, particularly in India and Phoenicia, dyeing has been carried out for over 5,000 years. The dyes were obtained from animal, vegetable or mineral origin, by far the greatest source of dyes has been from the plant kingdom, notably roots, berries, bark, leaves and wood, but only a few have ever been used on a commercial scale. The discovery of synthetic dyes late in the 19th century ended the large-scale market for natural dyes. These dyes are made from synthetic resources such as petroleum by-products, the first human-made organic aniline dye, mauveine, was discovered serendipitously by William Henry Perkin in 1856, the result of a failed attempt at the total synthesis of quinine. Other aniline dyes followed, such as fuchsine, safranine, many thousands of synthetic dyes have since been prepared. These may be natural or synthetic, other than pigmentation, they have a range of applications including organic dye lasers, optical media and camera sensors. This is the basic classification Dyes are classified according to their solubility, acid dyes are water-soluble anionic dyes that are applied to fibers such as silk, wool, nylon and modified acrylic fibers using neutral to acid dye baths. Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic groups in the fiber, acid dyes are not substantive to cellulosic fibers. Most synthetic food colors fall in this category, basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers, but find some use for wool and silk. Usually acetic acid is added to the dye bath to help the uptake of the dye onto the fiber, basic dyes are also used in the coloration of paper
9.
Gas
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Gas is one of the four fundamental states of matter. A pure gas may be made up of atoms, elemental molecules made from one type of atom. A gas mixture would contain a variety of pure gases much like the air, what distinguishes a gas from liquids and solids is the vast separation of the individual gas particles. This separation usually makes a colorless gas invisible to the human observer, the interaction of gas particles in the presence of electric and gravitational fields are considered negligible as indicated by the constant velocity vectors in the image. One type of commonly known gas is steam, the gaseous state of matter is found between the liquid and plasma states, the latter of which provides the upper temperature boundary for gases. Bounding the lower end of the temperature scale lie degenerative quantum gases which are gaining increasing attention, high-density atomic gases super cooled to incredibly low temperatures are classified by their statistical behavior as either a Bose gas or a Fermi gas. For a comprehensive listing of these states of matter see list of states of matter. The only chemical elements which are stable multi atom homonuclear molecules at temperature and pressure, are hydrogen, nitrogen and oxygen. These gases, when grouped together with the noble gases. Alternatively they are known as molecular gases to distinguish them from molecules that are also chemical compounds. The word gas is a neologism first used by the early 17th-century Flemish chemist J. B. van Helmont, according to Paracelsuss terminology, chaos meant something like ultra-rarefied water. An alternative story is that Van Helmonts word is corrupted from gahst and these four characteristics were repeatedly observed by scientists such as Robert Boyle, Jacques Charles, John Dalton, Joseph Gay-Lussac and Amedeo Avogadro for a variety of gases in various settings. Their detailed studies ultimately led to a relationship among these properties expressed by the ideal gas law. Gas particles are separated from one another, and consequently have weaker intermolecular bonds than liquids or solids. These intermolecular forces result from interactions between gas particles. Like-charged areas of different gas particles repel, while oppositely charged regions of different gas particles attract one another, transient, randomly induced charges exist across non-polar covalent bonds of molecules and electrostatic interactions caused by them are referred to as Van der Waals forces. The interaction of these forces varies within a substance which determines many of the physical properties unique to each gas. A comparison of boiling points for compounds formed by ionic and covalent bonds leads us to this conclusion, the drifting smoke particles in the image provides some insight into low pressure gas behavior
10.
Fire extinguisher
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A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on a fire, such as one which has reached the ceiling, endangers the user. Typically, a fire extinguisher consists of a cylindrical pressure vessel containing an agent which can be discharged to extinguish a fire. Fire extinguishers manufactured with non-cylindrical pressure vessels also exist, but are less common, in the United States, fire extinguishers in all buildings other than houses are generally required to be serviced and inspected by a fire protection service company at least annually. Some jurisdictions require more frequent service for fire extinguishers, the servicer places a tag on the extinguisher to indicate the type of service performed. There are two types of fire extinguishers, stored-pressure and cartridge-operated. In stored pressure units, the expellant is stored in the chamber as the firefighting agent itself. Depending on the agent used, different propellants are used, with dry chemical extinguishers, nitrogen is typically used, water and foam extinguishers typically use air. Stored pressure fire extinguishers are the most common type, Cartridge-operated extinguishers contain the expellant gas in a separate cartridge that is punctured prior to discharge, exposing the propellant to the extinguishing agent. This type is not as common, used primarily in areas such as industrial facilities and they have the advantage of simple and prompt recharge, allowing an operator to discharge the extinguisher, recharge it, and return to the fire in a reasonable amount of time. Unlike stored pressure types, these extinguishers use compressed carbon dioxide instead of nitrogen, although nitrogen cartridges are used on low temperature models. Cartridge operated extinguishers are available in dry chemical and dry powder types in the U. S. and in water, wetting agent, foam, dry chemical, Fire extinguishers are further divided into handheld and cart-mounted. Handheld extinguishers weigh from 0.5 to 14 kilograms, and are hence, cart-mounted units typically weigh more than 23 kilograms. These wheeled models are most commonly found at sites, airport runways, heliports, as well as docks. The first fire extinguisher of which there is any record was patented in England in 1723 by Ambrose Godfrey and it consisted of a cask of fire-extinguishing liquid containing a pewter chamber of gunpowder. This was connected with a system of fuses which were ignited, exploding the gunpowder and this device was probably used to a limited extent, as Bradleys Weekly Messenger for November 7,1729, refers to its efficiency in stopping a fire in London. The modern fire extinguisher was invented by British Captain George William Manby in 1818, the soda-acid extinguisher was first patented in 1866 by Francois Carlier of France, which mixed a solution of water and sodium bicarbonate with tartaric acid, producing the propellant CO2 gas. A soda-acid extinguisher was patented in the U. S. in 1881 by Almon M. Granger and his extinguisher used the reaction between sodium bicarbonate solution and sulfuric acid to expel pressurized water onto a fire
11.
Breathing gas
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A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Oxygen is the component for any breathing gas, at a partial pressure of between roughly 0.16 and 1.60 bar at the ambient pressure. The oxygen is usually the only metabolically active component unless the gas is an anaesthetic mixture, most breathing gases therefore are a mixture of oxygen and one or more inert gases. A safe breathing gas for use has three essential features, it must contain sufficient oxygen to support life, consciousness and work rate of the breather. It must not contain harmful gases, carbon monoxide and carbon dioxide are common poisons which may contaminate breathing gases. It must not become toxic when being breathed at high pressure such as when underwater, oxygen and nitrogen are examples of gases that become toxic under pressure. The techniques used to fill diving cylinders with gases other than air are called gas blending and it is common to provide the additional oxygen as a pure gas added to the breathing air at inhalation, or though a life-support system. Being cheap and simple to use, it is the most common diving gas. As its nitrogen component causes nitrogen narcosis, it is considered to have a depth limit of about 40 metres for most divers. It was much used in frogmens rebreathers, Nitrox is a mixture of oxygen and air, and generally refers to mixtures which are more than 21% oxygen. It can be used as a tool to accelerate in-water decompression stops or to decrease the risk of decompression sickness, Heliox is a mixture of oxygen and helium and is often used in the deep phase of a commercial deep dive to eliminate nitrogen narcosis. Heliair is a form of trimix that is blended from helium. It always has a 21,79 ratio of oxygen to nitrogen, Hydreliox is a mixture of oxygen, helium, and hydrogen and is used for dives below 130 metres in commercial diving. Hydrox, a gas mixture of hydrogen and oxygen, is used as a gas in very deep diving. Neox is a mixture of oxygen and neon sometimes employed in commercial diving. It is rarely used due to its cost, also, DCS symptoms produced by neon have a poor reputation, being widely reported to be more severe than those produced by an exactly equivalent dive-table and mix with helium. Oxygen must be present in every breathing gas and this is because it is essential to the human bodys metabolic process, which sustains life. The human body cannot store oxygen for use as it does with food
12.
Diving air compressor
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A low pressure diving air compressor usually has a delivery pressure of up to 30 bar, which is regulated to suit the depth of the dive. A high pressure diving compressor has a pressure which is usually over 150 bar. The pressure is limited by a valve which may be adjustable. High pressure diving compressors are generally three- or four-stage-reciprocating air compressors that are lubricated with a mineral or synthetic compressor oil free of toxic additives. Oil-lubricated compressors must only use lubricants specified by the manufacturer as suitable for use with breathing air. Special filters are used to clean the air of most residual oil, most oil lubricated compressors will have a wet sump at the bottom of the crankcase, and require the oil level to be within limits indicated by a sight glass or dipstick for proper lubrication. The compressor should also be level within the manufacturers specification while operating and these constraints ensure that the lubricant is in the right place for either the moving parts to contact it for splash lubrication, or for reliable suction to the oil pump. Low pressure diving compressors are usually single stage compressors as the pressure is relatively low. The compressed air output by the compressor must be filtered to make it fit for use as a breathing gas, for this reason, compressors must be carefully designed and maintained to ensure that oil contamination of the breathing gas is within safe limits. Oils used should be approved by the manufacturer and rated as safe for breathing air compressors. A range of mineral based and synthetic oils are supplied by several lubricant manufacturers for this application, carbon monoxide is a gas that is present in the exhaust gas of internal combustion engines, including those often used to drive compressors. It also comes from the breakdown of lubricating oil when compressors run too hot, CO is odorless, colorless, and tasteless. CO is deadly even in small quantities, because it binds with the hemoglobin in red blood cells. Breathing air compressors must be designed and placed so that the compressors intake is located in fresh air well away. Periodically, the air produced by a compressor must be tested to ensure it meets air purity standards, frequency of testing, contaminants that must be analysed, and the allowable limits vary between applications and jurisdictions. Surface supplied diving compressors are low-pressure and high-volume and they supply breathing air directly to a diver, through a control panel sometimes called a rack via a hose which is usually part of a group of hoses and cables called an umbilical. Their output is generally between 6 and 20 bar /100 and 300 psi and these compressors must be sufficiently powerful to deliver gas at a sufficient pressure and volume for multiple divers working at depths of up to about 60 m. Compressors used to fill scuba cylinders have a delivery pressure
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