A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. 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 Scuba diving is swimming underwater, or taking part in another activity while using a Scuba set. It is much used for sport diving and some sorts of work diving.

The word SCUBA is an acronym for Self-Contained Underwater Breathing Apparatus. Acronyms, initialisms, and alphabetisms are Abbreviations that are formed using the initial components in a phrase or name These initials originated in 1939 in the US Navy to refer to US military diver's rebreather sets. A frogman is someone who is trained to dive or swim in a military capacity often in combat A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas As with radar, the acronym has become so familiar that it is often not capitalized and is treated as an ordinary word; for example, it has been taken into the Welsh language as "sgwba". Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Welsh ( cy Cymraeg or cy y Gymraeg, kəmˈrɑːɨɡ and {{IPA|[ə ɡəmˈrɑːɨɡ]}}, is a member of the Brythonic branch of Celtic

Contents 1 Types of scuba sets 1.1 Open circuit scuba sets 1.1.1 Constant flow 1.1.2 With a demand regulator 1.1.2.1 "Twin-hose" open-circuit scuba 1.1.2.2 "Single-hose" open-circuit scuba 1.1.2.3 Cryogenic open-circuit scuba 1.2 Rebreathers 2 Duration of a dive 2.1 Air cylinders 3 Underwater alternatives to scuba 4 Breathing sets used out of water 5 History 6 Accessories 7 Notable early manufacturers 8 See also

Types of scuba sets

Modern scuba sets are of two types:

• open-circuit (In Europe, it is often called an "aqualung", see Aqua-Lung, first invented by Jacques Yves Cousteau and Emile Gagnan). Aqualung was the original name for the first open-circuit scuba diving equipment, developed by Emile Gagnan and Jacques Cousteau in 1943 Jacques-Yves Cousteau ( 11 June 1910 – 25 June 1997) was a French naval officer explorer, Ecologist, Émile Gagnan (November 1900 – 1979 was a French Engineer and co-inventor (together with Jacques-Yves Cousteau) of the demand-valve used for the first Here the diver breathes in from the set and out to waste. This type of equipment is relatively simple, making it cheaper and more reliable. The two-hose design originally used was the one designed by Cousteau and Gagnon. The single-hose design generally used today was invented in Australia by Ted Eldred. Edward ('Ted' Francis Eldred (16th December 1920 to August 2005 was a pioneer of Scuba diving in Australia.
• closed-circuit/semi-closed circuit (also referred to as a rebreather). A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas Here the diver breathes in from the set, and out back into the set where the exhaled gas is processed to make it fit to breathe again. These existed before the open-circuit sets and still exist today, but they are used less than open-circuit sets.

Both types of scuba provide a means of supplying air or other breathing gas, nearly always from a high pressure diving cylinder, and a harness to strap it to the diver's body. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five 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 diving cylinder, scuba tank or diving tank is used to store and transport high Pressure Breathing gas as a component of SCUBA (Self-Contained Most open-circuit scuba and some rebreathers have a demand regulator to control the supply of breathing gas. A diving regulator is a Pressure regulator used in a Scuba set that supplies the diver with breathing gas Some rebreathers only have a constant-flow regulator like in blowtorches. The meaning of " blowtorch " varies between Britain and the USA Some divers use the word "scuba" to mean open-circuit sets only.

Open circuit scuba sets

The duration of open-circuit dives is shorter than a rebreather dive, in proportion to the weight and bulk of the set. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas It can be uneconomic when used with expensive gas mixes such as heliox and trimix. See Heliox (cryogenic equipment for another use of the word Heliox Heliox is a Breathing gas composed of a mixture of Most divers use standard air (i. e. 21% Oxygen / 79% Nitrogen). The cylinder is nearly always worn on the back. "Twin sets" with two backpack cylinders were much more common in the 1960s than now; although twin cylinders (aka "doubles") are commonly used by technical divers for the increased duration and redundancy they provide. The 1960s decade refers to the years from the beginning of 1960 to the end of 1969 Submarine Products sold a sport air scuba with 3 backpack cylinders. Submarine Products Ltd were a diving gear manufacturer with a factory in Hexham in Northumberland in England. Sometimes cave divers have cylinders slung at their sides instead.

See diving cylinder for more information about the cylinders and how they are arranged. 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

Newspapers and television news often describe open circuit scuba wrongly as "oxygen" equipment, probably by false analogy from airplane pilots' oxygen cylinders. A newspaper is a written Publication containing News, information and Advertising, usually printed on low-cost paper called Newsprint. Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic News is any new information or information on Current events which is presented by print, broadcast, Internet, or Word of mouth Aviation refers to activities involving man-made flying devices ( Aircraft) including the people organizations and regulatory bodies involved with them Until Enriched Air Nitrox was widely accepted in the late 1990s, almost all sport scuba used simple compressed air. Nitrox refers to any gas mixture composed (excluding trace gases of nitrogen and oxygen this includes normal Air which is approximately 78% Nitrogen This allowed the scuba industry in the U. S. to bypass being supervised by the Food and Drug Administration (FDA), which defines non-air gas mixtures intended to prevent or treat diseases, as "drugs. " Exotic gas mixtures presently used in scuba are intended to prevent decompression illness in diving, but officially, the FDA appears to continue to believe that scuba divers all use compressed air. Decompression Illness (DCI is a term generally used to describe illness after a decrease in the ambient pressure that a body is exposed to

At partial pressures over about 1. 6 atmospheres, oxygen becomes toxic. Oxygen toxicity or oxygen toxicity syndrome (also known as the " Paul Bert effect" or the "Lorrain Smith effect" describes harmful effects caused Open-circuit scuba sets may supply various breathing gases; but rarely pure oxygen, except during decompression stops in technical diving. 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 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

Some divers use Enriched Air Nitrox, which has a higher percentage of oxygen, usually 32% or 36% (EAN32 and EAN36, respectively). Nitrox refers to any gas mixture composed (excluding trace gases of nitrogen and oxygen this includes normal Air which is approximately 78% Nitrogen This lets them stay underwater longer, because less nitrogen is absorbed into the body's tissues. The most common Nitrox blending method needs an oxygen service tank, which is a tank that has had any non-oxygen-compatible grease or rubber removed, by cleaning and replacing parts.

Constant flow

Constant flow scuba sets do not have a demand regulator; the breathing gas flows at a constant rate unless the diver switches it on and off by hand. They run out of air quicker than aqualungs. There were attempts at designing and using these before 1939, for diving and for industrial use. Examples were "Ohgushi's Peerless Respirator", and Commandant le Prieur's breathing sets: see Timeline of underwater technology. Yves Paul Gaston Le Prieur (1885 - died 1963 was an officer of the French navy and an inventor This is a Timeline of Underwater Technology. The entries marked ## are about Decompression tables Pre-industrial

With a demand regulator

This type of set consists of one or more diving cylinders containing breathing gas at high pressure (typically 200-300 Bar) connected to a diving regulator. 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 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 The bar (symbol bar) decibar (symbol dbar) and the millibar (symbol mbar, also mb are units of Pressure. A diving regulator is a Pressure regulator used in a Scuba set that supplies the diver with breathing gas The regulator supplies the diver with as much of the gas as needed, at a pressure suitable for breathing at the depth of the diver.

Colloquially this type of breathing set is sometimes (depending on the country of the English speaker) often called an aqualung; however, the word "Aqua-Lung" (note spelling) is a tradename protected by the Cousteau-Gagnan patent. A trade name, also known as a trading name or a business name, is the name which a Business trades under for commercial purposes although its registered Jacques-Yves Cousteau ( 11 June 1910 – 25 June 1997) was a French naval officer explorer, Ecologist, Émile Gagnan (November 1900 – 1979 was a French Engineer and co-inventor (together with Jacques-Yves Cousteau) of the demand-valve used for the first A patent is a set of Exclusive rights granted by a State to an inventor or his assignee for a fixed period of time in exchange for a disclosure of an The trademark is now owned by U. S. Divers.

"Twin-hose" open-circuit scuba

This is the first type of diving demand valve which came into general use, and the one that can be seen in classic 1960s SCUBA adventures, such as TV's Sea Hunt. Sea Hunt was an American Television adventure series from syndicator Ziv TV that ran from 1958 to 1961 and was popular in syndication

In this type of set, the two (or occasionally one or three) stages of the regulator are in a large circular valve assembly mounted on top of the cylinder pack. This type has two wide breathing tubes like those on many modern rebreathers, one for intake and one for exhalation. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas The return tube was not for rebreathing, but because the air exhaust needed to be as near as possible to the regulator's second stage diaphragm, to avoid pressure differences, which would cause a free-flow of gas, or extra resistance to breathing, according to the diver's orientation in the water: head-up, head-down, level. In mechanics, a diaphragm is a sheet of a semi-flexible material anchored at its periphery and most often round in shape In modern single-hose sets this problem is avoided by moving the second-stage regulator to the diver's mouthpiece. The twin-hose sets came with a mouthpiece as standard, but a fullface mask was an option. A full-face diving mask is a type of Diving mask that seals the whole of the diver's Face from the water and contains a mouthpiece or Demand valve Another optional extra was a mouthpiece that also had a snorkel attached and a valve to switch between aqualung and snorkel.

Note the correct layout of this type, in the image to the right. In comics there have been thousands of drawings of two-cylinder twin-hose aqualungs shown wrongly, with one wide breathing tube coming straight out of each cylinder top with no regulator. Comics (via Latin from the Greek "" kōmikos, of or pertaining to "comedy" from kōmos "revel"

"Single-hose" open-circuit scuba

Most modern open-circuit scuba sets have a diving regulator consisting of a first-stage pressure-reducing valve fastened over the diving cylinder's output valve. A diving regulator is a Pressure regulator used in a Scuba set that supplies the diver with breathing gas 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 This valve cuts the pressure from the cylinder, which may be up to 300 bar, to a constant lower pressure, often about 10 bar above the ambient pressure, which is used in the "low pressure" part of the system. A relatively thin low-pressure hose links this with the second-stage regulator, or "demand valve," which is located in the mouthpiece. Exhalation occurs out of a one-way diaphragm in the chamber of the demand valve, directly into the water quite close to the diver's mouth. This configuration type is called "single hose". The first make of this sort of scuba was the Porpoise, which was made in Melbourne, Australia by Ted Eldred. Porpoise is a Tradename for scuba developed by Ted Eldred in Australia and made there from the late 1940's onwards Melbourne ( is the second most populous city in Australia, with a Metropolitan area population of approximately 3 Some early single hose scuba sets used full-face masks instead of a mouthpiece, such as those made by Desco and Scott Aviation (who continue to make breathing units of this configuration for use by firefighters). Firefighters are rescuers extensively trained primarily to put out hazardous Fires that threaten civilian populations and property to rescue people from car accidents collapsed

The first scuba set tradenamed Porpoise was a rebreather, but when a demonstration resulted in a diver passing out, Ted began to develop the single-hose open-circuit scuba system. A trade name, also known as a trading name or a business name, is the name which a Business trades under for commercial purposes although its registered Its regulator's first stage and second stage had to be separated to avoid the Cousteau-Gagnan patent, which protected the double-hose scuba. A patent is a set of Exclusive rights granted by a State to an inventor or his assignee for a fixed period of time in exchange for a disclosure of an In the process, Eldred also improved performance.

All modern scuba sets have a spare second-stage demand valve on its own second hose, a configuration called an "octopus" because it often has more hoses for other purposes coming out of the primary regulator on the cylinder top. This second "second-stage" regulator and hose, or "alternate air source", or "safe secondary" or "safe-second" for short, is typically yellow (signaling that it is an emergency or backup device). It is often worn secured into a clip on the stab-jacket or a special friction plug on a diver's chest, easily available to be grabbed by, or offered to, a second diver short of air. In so doing, this second mouthpiece eliminates the need for two divers who need to share a cylinder to "buddy-breathe," by trading off the same mouthpiece. Diving instructors continue to teach buddy-breathing; then they show the new method that has superseded it. The original octopus idea was conceived by Sheck Exley as a way for single-file-swimming cave divers to share air in a narrow tunnel, but has now become the standard in recreational diving. Sheck Exley ( April 1, 1949 &ndash April 6, 1994) was a Cave-diving pioneer Modern "octopus" type primary-stage regulators also typically feature high-pressure ports for use by dive-computer pressure-sensors, and additional ports for additional low-pressure hoses for inflation of dry suits and buoyancy compensator (BC) devices.

Increasingly, in the 21st century, "safety" secondary mouthpieces have been combined with the inflator and exhaust assembly of buoyancy compensator (BC) devices. This combination eliminates the need for a separate low pressure hose for the BC. Some diving schools now suggest that a diver offer another diver in trouble their primary mouthpiece (i. e. the one in their mouth), before going to their own safe-secondary. The idea here is that the diver not in trouble has much more time to sort things out with his/her own equipment after temporarily losing ability to breathe.

Cryogenic open-circuit scuba

There have been designs for a cryogenic open-circuit scuba which has liquid-air tanks instead of cylinders.

• Jordan Klein designed a cryogenic open-circuit scuba called "Mako" and made at least a prototype. A prototype is an original type form or instance of something serving as a typical example basis or standard for other things of the same category
• The Russian Kriolang (from Greek cryo- (= "frost") + English "lung") was copied from Jordan Klein's "Mako" cryogenic open-circuit scuba. Janwillem Bech's rebreather site shows pictures of a Kriolang that was made in 1974. Its diving duration is likely several hours. It would have to be filled immediately before use.
• SCAMP (Supercritical Air Mobility Pack) is an out-of-water liquid-air open-circuit breathing set designed by NASA by adapting space suit technology. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program A space suit is a complex system of Garments equipment and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space

Rebreathers

Main article: Rebreather

With rebreathers, the gas the diver exhales is stored between breaths in a "counterlung". A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas 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 In some rebreathers, one-way valves direct the gas through a "loop". In other rebreathers, the inhaled and exhaled gas goes back and forth along a single tube: this is called the pendulum system. A pendulum is a mass that is attached to a pivot from which it can swing freely The oxygen consumed by the diver is replaced, nearly always from a cylinder. 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 The exhaled carbon dioxide generated by the diver is removed by passing the gas through a "scrubber": a canister full of soda lime. Soda lime is a mixture of Chemicals used in granular form in closed breathing environments such as General anaesthesia, Submarines Rebreathers Then the gas is fit to be re-inhaled. This type of scuba equipment is known as 'closed circuit'.

Since 80% or more of the oxygen remains in normal exhaled gas, and is thus wasted, rebreathers use gas very economically, making longer dives possible and special mixes cheaper to use at the expense of more complicated technology and more experience and longer training. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas There are three variants of rebreather: oxygen rebreathers, semi-closed circuit rebreathers, and fully closed circuit rebreathers. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas

The rebreather's economic use of gas, typically 1. 6 litres of oxygen per minute, allows dives of much longer duration than is possible with open circuit equipment where gas consumption is typically 10 times higher. Oxygen rebreathers have a maximum operating depth of around 6 metres / 18 feet, but several types of fully closed circuit rebreathers, when using a helium-based diluent, can dive deeper than 100 metres / 330 feet. In Technical diving, the maximum operating depth (MOD of a Breathing gas is the depth at which the Partial pressure of Oxygen (ppO2 Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical The main limiting factors on rebreathers are the duration of the carbon dioxide scrubber, which is generally at least 3 hours, and that the scrubber gets less efficient at depth because the scrubber's inside is more crowded with diluent molecules hindering the carbon dioxide molecules from reaching the absorbent as quickly.

Duration of a dive

The duration of an open-circuit dive depends on factors such as the capacity (volume of gas) in the diving cylinder, the depth of the dive and the breathing rate of the diver. 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

An open circuit diver whose breathing rate at the surface (atmospheric pressure) is 15 litres per minute will consume 3 x 15 = 45 litres of gas per minute at 20 metres. [(20 m/10 m per bar) + 1 bar atmospheric pressure] × 15 L/min = 45 L/min). If an 11 litre cylinder filled to 200 bar is used until there is a reserve of 17% there is (83% × 200 × 11) = 1826 litres. At 45 L/min the dive at depth will be a maximum of 40. 5 minutes (1826/45). These depths and times are typical of experienced sport divers leisurely exploring a coral reef using 200 bar aluminum cylinders rented from a commercial sport diving operation in most tropical island or coastal resorts. Coral reefs are Aragonite structures produced by living organisms found in marine waters with little to no nutrients in the water The Tropics are centered on the Equator and limited in Latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' (23

A semi-closed circuit rebreather dive is about three times the length of the equivalent open circuit dive; gas is recycled but fresh gas must be constantly injected to replace at least the oxygen used, and any excess gas from this must be vented. Although it uses gas more economically, the weight of the rebreathing equipment means the diver carries smaller cylinders. Still, most semi-closed systems allow at least twice the duration of open circuit systems (around 2 hours).

An oxygen rebreather diver or a fully closed circuit rebreather diver consumes about 1 litre of oxygen per minute. Except during ascent or descent, the fully closed circuit rebreather that is operating correctly uses no or very little diluent. So, a diver with a 3 litre oxygen cylinder filled to 200 bar who leaves 25% in reserve will be able to do a 450 minute = 7. 5 hour dive (3 L × 200 bar × 0. 75 / 1). The life of the soda lime scrubber is likely to be less than this and so will be the limiting factor of the dive. Soda lime is a mixture of Chemicals used in granular form in closed breathing environments such as General anaesthesia, Submarines Rebreathers

In practice, dive times are more often influenced by other factors such as water temperature and the need for safe ascent (see decompression sickness). 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

Air cylinders

Main article: Diving cylinder

Air cylinders used for scuba diving come in various sizes and materials and are typically designated by material (aluminium, steel, high-pressure steel, etc). 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 A gas cylinder or tank is a Pressure vessel used to store Gases at high Pressure. WikipediaNaming Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 In the US the size is designated by how much air they contain when expanded to 1 atmosphere (80, 100, 120 cubic feet, etc), while in Europe the size is given as their internal volume (10 liter, 12 liter, etc). The most common is the "Aluminum 80", which will give an average experienced diver from 40 to 60 minutes of dive time under common dive conditions.

Air cylinder pressure will vary according to the type of material used, ranging from 200 bar up to 300 bar

Aluminium cylinders are less expensive than steel and have been known to last for 20 years with standard regular maintenance. The drawback is that aluminium cylinders are neutrally buoyant when full, and positively buoyant when nearing empty. This results in having to monitor buoyancy during the dive more closely so as not to experience the "express elevator to the surface". Aluminium tanks also need the diver to carry more weight. Divers often prefer to use steel tanks as they are negatively buoyant when full and neutral when empty. Many steel tanks also accept higher pressure fills, giving more capacity for a longer dive for the same size of cylinder.

Underwater alternatives to scuba

There are alternative methods that a person can use to survive and function while underwater, including:

• free-diving - swimming underwater on a single breath of air. Free diving is any of various aquatic activities that share the practice of breath-holding Underwater diving.
• snorkeling - a form of free-diving where the diver's mouth and nose can remain underwater when breathing, because the diver is able to breathe at the surface through a short tube known as a snorkel. Snorkeling ( British spelling: snorkelling) is the practice of Swimming at the surface of a body of water while equipped with a Diving mask, a Snorkeling ( British spelling: snorkelling) is the practice of Swimming at the surface of a body of water while equipped with a Diving mask, a
• surface supplied diving - originally used in professional diving for long or deep dives where an umbilical line connects the diver with the surface providing breathing gas, and sometimes warm water to heat the diving suit, and usually nowadays voice communications. Surface supplied diving (also known as Hooka diving refers to divers using equipment supplied with Breathing gas using an umbilical cord Hardhat diving redirects here Often "hardhat diving" is used to specifically mean diving in the old-type Standard diving dress. 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 suit is a garment or device designed to protect a diver from the Underwater environment Some tourist resorts now offer a surface supplied diving arrangement, trademarked as Snuba, as an introduction to diving for the inexperienced. A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual Snuba is a trade name (of Snuba International Inc for a underwater breathing system Using the same type of equipment as scuba diving, the diver breathes from compressed air tanks, which float on a free floating raft at the surface, allowing the diver only 20-30 feet (6-9 m) of depth to travel.
• Atmospheric diving suit - an armored suit which protects the diver from the surrounding water pressure. Atmospheric Diving Suit or ADS is a small one-man articulated Submersible of Anthropomorphic form which resembles a suit of armour with elaborate pressure
• Liquid breathing - so far, in the real world, liquid breathing for humans is only laboratory experiments, and (one lung at a time) medical treatment. Liquid breathing is a form of respiration in which a normally air-breathing organism breathes an Oxygen -rich Liquid (usually a Perfluorocarbon It has possibilities of being used for very deep diving. It is memorably portrayed in the film "The Abyss". The Abyss is a Science fiction film that was written and directed by James Cameron in 1989.
• Artificial gills (human) - these are mostly science fiction. Artificial gills are devices that exist in Science fiction, and being developed in reality to extract Oxygen dissolved in Water, thus allowing Humans In the real world they have to process a massive amount of water to extract enough oxygen to supply an active diver, and processing this much water takes a great deal of energy (possible for cold-blooded fish, but harder for humans with higher metabolic rates). But see Like-A-Fish for an attempt to develop real artificial gills for divers. Artificial gills are devices that exist in Science fiction, and being developed in reality to extract Oxygen dissolved in Water, thus allowing Humans

Breathing sets used out of water

Breathing sets operating on the above principles are not only used underwater but in other situations where the atmosphere is dangerous (little oxygen, poisonous etc).

• Firefighting
• Other jobs out of water, e. Firefighters are rescuers extensively trained primarily to put out hazardous Fires that threaten civilian populations and property to rescue people from car accidents collapsed g. welding in a confined space
• Mining, especially mine rescue
• Operations in enclosed or poorly ventilated areas, e. Welding is a fabrication process that joins materials usually Metals or Thermoplastics by causing coalescence. Mining is the extraction of valuable Minerals or other geological materials from the earth usually (but not always from an Ore body Rescue refers to operations that usually involve the saving of Life, or prevention of Injury. g. large fluid or gas containers.

These breathing sets are nowadays called SCBA (Self Contained Breathing Apparatus) (The initials SCBA have had other meanings). self contained breathing apparatus, or SCBA, sometimes referred to as a Compressed Air Breathing Apparatus (CABA or simply Breathing Apparatus (BA is self contained breathing apparatus, or SCBA, sometimes referred to as a Compressed Air Breathing Apparatus (CABA or simply Breathing Apparatus (BA is The first open-circuit industrial breathing sets were designed by modifying the design of the Cousteau aqualung.

Industrial rebreathers have been used since soon after 1900. Year 1900 ( MCM) was an exceptional Common year starting on Monday (link will display the full calendar of the Gregorian calendar

Rebreather technology is also used in space suits. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas A space suit is a complex system of Garments equipment and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space

History

Today's scuba sets are mostly similar to the ideas suggested by Alexander Lodygin many years before the term appeared. Alexander Nikolayevich Lodygin ( October 18 1847 – March 16 1923) ( Александр Николаевич Лодыгин in

A predecessor to scuba gear, the Momson lung, was used as emergency escape gear by WWII submariners. The Momsen lung was a primitive underwater breathing apparatus used before and during World War II by American submariners as emergency escape gear

Jacques-Yves Cousteau and Emile Gagnan invented the first commercially successful open circuit type of SCUBA diving equipment, the Aqua-Lung (often spelled "aqualung") in 1943. Jacques-Yves Cousteau ( 11 June 1910 – 25 June 1997) was a French naval officer explorer, Ecologist, Émile Gagnan (November 1900 – 1979 was a French Engineer and co-inventor (together with Jacques-Yves Cousteau) of the demand-valve used for the first Aqualung was the original name for the first open-circuit scuba diving equipment, developed by Emile Gagnan and Jacques Cousteau in 1943 Year 1943 ( MCMXLIII) was a Common year starting on Friday (the link will display full 1943 calendar of the Gregorian calendar. Among the things that prompted Cousteau to develop efficient air-breathing diving free-swimming diving gear, were two oxygen toxicity accidents that he had with rebreathers. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas The Cousteau Gagnan patent was licensed to Siebe Gorman of England. Siebe Gorman was allowed to sell in Commonwealth countries but had difficulty in meeting the demand and the US patent prevented others from making the product. Ted Eldred of Melbourne, Australia met this demand by developing the single hose regulator used today. Ted sold his first Porpoise model CA single hose scuba in early in 1952.

Another SCUBA pioneer was John Haven "Jack" Emerson, who also developed the iron lung and other breathing apparatus. John Haven "Jack" Emerson ( February 5, 1906 – February 4, 1997) was an American Inventor of Biomedical An iron lung is a large machine that enables a person to breathe when normal Muscle control has been lost or the work of breathing exceeds the person's ability

Before 1971 all breathing sets including scuba came with a plain harness of straps with buckles like on a rucksack or spray-tank-pack. The buckles were usually quick-release. Many did not have a backpack plate, but the cylinders were held directly against the diver's back. Sport scuba usually had quick-release fastenings instead of ordinary buckles. The harnesses of many diving rebreathers made by Siebe Gorman included a large back-sheet of strong reinforced rubber. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas Siebe Gorman & Company Ltd was a British company which developed Diving equipment and breathing equipment and worked on Commercial diving and Marine

In the beginning scuba divers dived without any buoyancy aid. In emergency they had to jettison their weights. In the 1960s adjustable buoyancy life jackets for aqualung-type scuba became available; one early make was Fenzy. The ABLJ is used for two purposes, one to adjust the buoyancy of the diver to compensate for loss of buoyancy (chiefly due to compression of neoprene wetsuit) and more importantly as a lifejacket that can be rapidly inflated even at depth. Neoprene or polychloroprene is a family of synthetic Rubbers that are produced by Polymerization of Chloroprene. A wetsuit is a protective garment used for watersports such as Scuba diving, Surfing, Windsurfing, Kitesurfing, and Triathlon It was put on before putting on the cylinder harness. The first were inflated with a small carbon dioxide cylinder, later with a small air cylinder. An extra feed from the first stage regulator lets the life jacket be controlled as a buoyancy aid.

Accessories

In modern scuba sets, a buoyancy compensator (BC) or buoyancy control device (BCD), such as a back-mounted wing or stabilizer jacket (otherwise known as a 'stab jacket'), is built into the scuba set harness. Although strictly speaking this is not a part of the breathing apparatus, it is usually connected to the diver's air supply, in order to provide easy inflation of the device. This can usually also be done manually via a mouthpiece, in order to save tank air while on the surface. The bladders inside the BCD inflate with air from the ‘direct feed’ to increase the volume of the SCUBA equipment and cause the diver to float. Another button deflates the BCD and decreases the volume of the equipment and causes the diver to sink. Certain BCD's allow for integrated weight, meaning that the BCD has special pockets for the weights that can be dumped easily in case of an emergency. The aim of using the BCD, whilst underwater, is to keep the diver neutrally buoyant, i. e. neither floating up or sinking. The BCD is used to compensate for the compression of a wet suit, and to compensate for the decrease of the diver's mass as the air from the cylinder is breathed away.

Diving weighting systems, ranging from 2 to 15 kilograms, increase density of the scuba diver to compensate for the buoyancy of diving equipment, allowing the diver to fully submerge underwater with ease by obtaining neutral or slightly negative buoyancy. Divers wear weighting systems, weight belts or weights, generally made of Lead, to counteract the Buoyancy of other Diving equipment While weighting systems originally consisted of solid lead blocks attached to a belt around the diver's waist, some modern diving weighting systems are now incorporated into the BCD. Divers wear weighting systems, weight belts or weights, generally made of Lead, to counteract the Buoyancy of other Diving equipment These systems use small nylon bags of lead shot pellets which are distributed throughout the BCD, allowing a diver to gain a better overall weight distribution leading to a more horizontal position in the water. There are cases of lead weights being threaded on the straps holding the cylinder into the BCD.

Many modern rebreathers use advanced electronics to monitor and regulate the composition of the breathing gas. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical

Some scuba sets incorporate attached extra stage cylinders, as bailout in case the main breathing gas supply is used up or malfunctions, or containing another gas mixture. 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 If these extra cylinders are small, they are sometimes called "pony cylinders". A pony bottle is a small Diving cylinder, often of only a few litres capacity which is filled from a main tank before a dive and fitted with its own independent regulator They often have their own demand regulators and mouthpieces, and if so, they are technically distinct extra scuba sets. A diving regulator is a Pressure regulator used in a Scuba set that supplies the diver with breathing gas

The diver may carry two or more sets of breathing equipment to provide redundant alternative gas systems in the event that the other fails or is exhausted. Modern recreational rigs most often have two regulators connected to a single tank, in case the primary regulator fails or another diver runs out of air. Some divers instead connect their backup regulator to a smaller "pony cylinder" for extra safety, and there are also emergency systems which mount a simple regulator directly to the top of a small cylinder. Rebreather divers often carry a side-slung open-circuit "bail out" to be used in the event the rebreather fails.

In technical diving, the diver may carry different equipment for different phases of the dive; some breathing gas mixes may only be used at depth, such as trimix and others, such as pure oxygen, which only may be used during decompression stops in shallow water. 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 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 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 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 heaviest cylinders are generally carried on the back supported from a backplate while others are side slung from strong points on the backplate. A backplate and wing (often abbreviated as BP&W or BP/W) is a type of buoyancy compensation device (BCD worn by scuba divers

When the diver carries many diving cylinders, especially those made of steel, lack of buoyancy becomes a problem. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 In Physics, buoyancy ( BrE IPA: /ˈbɔɪənsi/ is the upward Force on an object produced by the surrounding liquid or gas in which it is High capacity buoyancy compensators are used to allow the diver to control his or her depth.

An excess of tubes and connections passing through the water tend to decrease diving performance by causing hydrodynamic drag in swimming. Fluid dynamics is the sub-discipline of Fluid mechanics dealing with fluid flow: Fluids ( Liquids and Gases in motion In Fluid dynamics, drag (sometimes called fluid resistance) is the force that resists the movement of a Solid object through a Fluid (a

Some diver training organizations and groups of divers teach techniques, such as DIR diving for configuring diving equipment. This page lists SCUBA Diver training organizations Commercial diving: Surface supplied air training organizations International The fundamental item of diving equipment used by divers is the SCUBA equipment, such as the Aqualung or Rebreather.

Notable early manufacturers

Normalair is a firm that is now part of the Honeywell Corporation based in Yeovil (UK). Yeovil (ˈjovɪl is a town in south Somerset, England, on the A30 and A37. They made an early make of single-hose aqualung that had a fullface mask as standard. A full-face diving mask is a type of Diving mask that seals the whole of the diver's Face from the water and contains a mouthpiece or Demand valve Normalair provided the Deep-Dive 500 rebreather sets used by James Bond 007 in the 1981 film For Your Eyes Only. A rebreather is a type of Breathing set that provides a Breathing gas containing Oxygen and recycled exhaled gas James Bond 007 is a Fictional character created in 1953 by writer Ian Fleming, who featured him in twelve Novels and two Short story For Your Eyes Only ( 1981) is the 12th Spy film in the James Bond series, and the fifth to star Roger Moore as MI6

Captain Trevor Hampton in the 1950s or 1960s designed an early single-hose aqualung with a fullface mask with a circular window which was a very big and thus very sensitive demand regulator diaphragm. (Captain Trevor Hampton AFC (1912 - 2002 was one of the United Kingdom 's first Scuba divers and helped to develop Sport diving in the UK But when he patented it, the Navy requisitioned the patent, and by the time the Navy found no use in the patent and released it, the market had moved on and he got no use from the patent.

The first commercially successful single hose scuba inventor was Ted Eldred of Melbourne, Australia (Porpoise 1952), although many people were working on it at the same time. Edward ('Ted' Francis Eldred (16th December 1920 to August 2005 was a pioneer of Scuba diving in Australia. Melbourne ( is the second most populous city in Australia, with a Metropolitan area population of approximately 3 Porpoise is a Tradename for scuba developed by Ted Eldred in Australia and made there from the late 1940's onwards

The second company to make single hose scuba was also in Melbourne. It was made by Jim Ager who owned Air Dive Pty. Ltd. His regulator was the Sea Bee (1955). Jim still makes scuba regulators and is the longest continuous maker of single hose scuba in the world.

See also

• Timeline of underwater technology
• List of diver training organizations

This is a Timeline of Underwater Technology. The entries marked ## are about Decompression tables Pre-industrial This page lists SCUBA Diver training organizations Commercial diving: Surface supplied air training organizations International

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