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 as SCUBA equipment, surface supplied diving equipment, recompression chambers, submarines, space suits, spacecraft and anaesthetic machines. Layers of Atmosphere (NOAA) Air redirects here. ... // SCUBA is an acronym for Self-Contained Underwater Breathing Apparatus. ... Surface supplied diver at the Monterey Bay Aquarium, Monterey, California Surface supplied diving refers to divers using equipment supplied with breathing gas using an umbilical cord from the surface, often from a diving support vessel but possibly, indirectly via a diving bell. ... A recompression chamber is a pressure vessel used to treat divers suffering from certain diving disorders such as decompression sickness. ... German UC-1 class World War I submarine A model of Günther Priens Unterseeboot 47 (U-47), German WWII Type VII diesel-electric hunter Typhoon class nuclear ballistic missile submarine USS Virginia, a Virginia-class nuclear attack (SSN) submarine A submarine is a specialized watercraft that can operate... Apollo 15 space suit A spacesuit 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. ... A spacecraft is a vessel, craft or device designed to operate beyond the surface of the Earth in outer space. ... An anaesthetic machine The anaesthetic machine (or anesthesia machine in America) is used by anaesthetists to support the administration of anaesthesia. ...

Most breathing gases are a mixture of oxygen and one or more inert gases. All breathing gases are alternatives to air and have been developed to improve on the performance of air by reducing the risk of decompression sickness, reducing the duration of decompression stops, reducing nitrogen narcosis or allowing safer deep diving. Decompression sickness (DCS), the diver’s disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. ... 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 in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ... Nitrogen narcosis or inert gas narcosis is a reversible alteration in consciousness producing a state similar to alcohol intoxication in SCUBA divers at depth. ... The meaning of term deep diving depends on the level of the divers diver training, diving equipment, breathing gas and surface support: in recreational diving, 30 metres / 100 feet may be a deep dive in technical diving, 60 metres / 200 feet may be a deep dive in surface supplied...

A safe breathing gas has three essential features:

• it must contain sufficient oxygen to support the life, consciousness and work rate of the breather.
• it must not contain harmful gases. Carbon monoxide and carbon dioxide are common poisons in breathing gases. There are many others.
• 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. General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin, Canberra. ... An underwater scene just beneath the surface. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... 12 litre and 3 litre steel diving cylinders A diving cylinder or SCUBA tank is used to store and transport high pressure breathing gas as a component of an Aqua-Lung. ... Air, oxygen and helium gas blending system Gas blending or gas mixing is the filling of diving cylinders with non-air breathing gases. ...

With oxygen mask strapped tightly for a good oxygen seal a diver breathes oxygen to remove nitrogen from the bloodstream to prevent decompression sickness.

Image File history File links Oxymask. ... Image File history File links Oxymask. ... Breathing 100% oxygen from a tight fitting pressure demand oxygen mask An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. ... Decompression sickness (DCS), the diver’s disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. ...

Common diving breathing gases

Common diving breathing gases are:

• Air is a mixture of 21% oxygen, 78% nitrogen, and approximately 1% other trace gases; to simplify calculations this last 1% is usually treated as if it were nitrogen. 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 safe depth limit of about 40 metres (130 feet) for most divers.
• Pure oxygen is mainly used to speed the shallow decompression stops at the end of a technical dive. It was much used in frogmen's rebreathers.
• Nitrox is a mixture of oxygen and air, and generally refers to mixtures which are more than 21% oxygen. It is mainly used instead of air to accelerate decompression or to decrease the risk of decompression sickness.
• Trimix is a mixture of oxygen, nitrogen and helium and is often used at depth in technical diving and commercial diving instead of air to reduce nitrogen narcosis.
• 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 easily blended from helium and air without using pure oxygen. It always has a 21:79 ratio of oxygen to nitrogen; the balance of the mix is helium.
• Hydreliox is a mixture of oxygen, helium, and hydrogen and is used for dives below 130 metres in commercial diving.
• Neox is a mixture of oxygen and neon sometimes employed for in deep commercial diving. It is rarely used due to its cost. Also, DCS symptoms produced by neon ("neox bends") have a poor reputation, being widely reported to be more severe than those produced by an exactly equivalent dive-table and mix with helium.

General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Technical diving is a form of SCUBA diving that exceeds the scope of recreational diving. ... // This page describes a type of scuba diver. ... A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycles exhaled gas. ... Nitrox refers to any gas mixture composed (excluding trace gases) of nitrogen and oxygen; this includes normal air which is approximately 78% nitrogen and 21% oxygen, with around 1% other gases. ... Decompression sickness (DCS), the diver’s disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. ... Trimix is a breathing gas, consisting of oxygen, helium and nitrogen, and is often used during the deep phase of dives carried out using Technical diving techniques. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Technical diving is a form of SCUBA diving that exceeds the scope of recreational diving. ... It has been suggested that this article or section be merged with Underwater diving. ... Heliox is a gas that is composed of a mixture of helium (He) and oxygen (O2). ... Heliair is a breathing gas consisting of mixture of oxygen, nitrogen and helium and is often used during the deep phase of dives carried out using technical diving techniques. ... Hydreliox is an exotic gas mixture used primarily for research and scientific deep diving, usually below 130 metres (429 feet). ... This article is about the chemistry of hydrogen. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ...

Individual component gases

Oxygen

Oxygen (O₂) must be present in every breathing gas. This is because it is essential to the human body's metabolic process, which sustains life. The human body cannot store oxygen for later use as it does with food. If the body is deprived of oxygen for more than a few minutes, unconsciousness and death result. The tissues and organs within the body (notably the heart and brain) are damaged if deprived of oxygen for much longer than four minutes. General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Human anatomy or anthropotomy is a special field within anatomy. ... Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... In biology, an organ (Latin: organum, instrument, tool) is a group of tissues that perform a specific function or group of functions. ...

The proportion of oxygen in a breathing gas determines the maximum operating depth, the deepest the mixture gas can safely be used: In technical diving, the maximum operating depth (MOD) of a breathing gas is the depth at which the partial pressure of oxygen (ppO2) of the gas mix exceeds a safe limit. ...

• hypoxic mixes, strictly, contain less than 21% oxygen, although often a boundary of 16% is used, and are designed only to be breathed at depth as a "bottom gas" where the higher pressure increases the partial pressure of oxygen to a safe level. Trimix, Heliox and Heliair are used to create typical hypoxic mixes and are used in technical diving as deep breathing gases.
• normoxic mixes have the same proportion of oxygen as air, 21%. The maximum operating depth of a normoxic mix could be as shallow as 47 metres (155 feet). Trimix with between 17% and 21% oxygen is often described as normoxic because it contains a high enough proportion of oxygen to be safe to breathe at the surface.
• hyperoxic mixes have a more oxygen than 21%. Enriched Air Nitrox (EAN) is a typical hyperoxic breathing gas. Hyperoxic mixtures, when compared to air, cause oxygen toxicity at shallower depths but can be used to shorten decompression stops by drawing dissolved inert gases out of the body more quickly.

The minimum safe partial pressure of oxygen in a breathing gas is commonly held to be 16 kPa (0.16 bar). Below this partial pressure the diver may be at risk of unconsciousness and death due to hypoxia, depending on factors including individual physiology and level of exertion. When a hypoxic mix is breathed in shallow water it may not have a high enough ppO2 to keep the diver conscious. For this reason normoxic or hyperoxic "travel gases" are used at medium depth between the "bottom" and "decompression" phases of the dive. In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. ... Trimix is a breathing gas, consisting of oxygen, helium and nitrogen, and is often used during the deep phase of dives carried out using Technical diving techniques. ... Heliox is a gas that is composed of a mixture of helium (He) and oxygen (O2). ... Heliair is a breathing gas consisting of mixture of oxygen, nitrogen and helium and is often used during the deep phase of dives carried out using technical diving techniques. ... Technical diving is a form of SCUBA diving that exceeds the scope of recreational diving. ... Nitrox refers to any gas mixture composed (excluding trace gases) of nitrogen and oxygen; this includes normal air which is approximately 79% nitrogen and 21% oxygen (although around 1% is actually other gases). ... Oxygen toxicity or oxygen toxicity syndrome is severe hyperoxia caused by breathing oxygen at elevated partial pressures. ... 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 in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ... In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ...

The maximum safe partial pressure of oxygen in a breathing gas depends on exposure time, the level of exercise and the security of the breathing equipment being used. It is typically between 100 kPa (1 bar) and 160 kPa (1.6 bar) but for dives of less than three hours is commonly considered to be 140 kPa (1.4 bar), although the U.S. Navy has been known to authorize dives with a partial oxygen pressure of as much as 180 kPa (1.8 bar). At high partial pressures or longer exposures, the diver risks oxygen toxicity including a seizure similar to an epileptic fit. Each breathing gas has a maximum operating depth that is determined by its oxygen content. This article is about the medical term, epileptic seizure, as distinct from psychogenic non-epileptic seizure. ... In technical diving, the maximum operating depth (MOD) of a breathing gas is the depth at which the partial pressure of oxygen (ppO2) of the gas mix exceeds a safe limit. ...

Oxygen analysers are used to measure the partial pressure of oxygen in the gas mix. An electro-galvanic fuel cell is an electrical device used to measure the concentration of oxygen gas in SCUBA diving and medical equipment. ...

Filling a diving cylinder with pure oxygen costs around five times more than filling it with compressed air. As oxygen supports combustion and causes rust in diving cylinders, it should be handled with respect when gas blending. 12 litre and 3 litre steel diving cylinders A diving cylinder or SCUBA tank is used to store and transport high pressure breathing gas as a component of an Aqua-Lung. ... Air, oxygen and helium gas blending system Gas blending or gas mixing is the filling of diving cylinders with non-air breathing gases. ...

Oxygen is obtained by fractional distillation of liquid air. Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. ... Liquid air is air that has been liquified by compression and cooled to very low temperatures. ...

Divox

"Divox" is oxygen. In the Netherlands, pure oxygen for breathing purposes is regarded as medicinal as opposed to industrial oxygen, such as that used in welding, and is only available on medical prescription. The diving industry "created" Divox and registered it as a trademark to circumvent the strict rules concerning medicinal oxygen thus making it easier for (recreational) scuba divers to obtain oxygen for blending their breathing gas. General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ... A medical prescription ) is an order (often in written form) by a qualified health care professional to a pharmacist or other therapist for a treatment to be provided to their patient. ... A trademark, trade mark, ™ or ®[1] is a distinctive sign of some kind which is used by an organization to uniquely identify itself and its products and services to consumers, and to distinguish the organization and its products or services from those of other organizations. ... Scuba divers exploring fish and coral. ...

Nitrogen

Nitrogen (N₂) is an inert gas and the main component of air, the cheapest and most common breathing gas used for diving. It causes nitrogen narcosis in the diver, so its use is limited to shallower dives. Nitrogen can cause decompression sickness. General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... An inert gas is any gas that is not reactive under normal circumstances. ... Layers of Atmosphere (NOAA) Air redirects here. ... Nitrogen narcosis or inert gas narcosis is a reversible alteration in consciousness producing a state similar to alcohol intoxication in SCUBA divers at depth. ... Decompression sickness (DCS), the diver’s disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. ...

Equivalent air depth is often used to help design a breathing gas mix by determining the maximum nitrogen content for a particular depth of dive. Many divers find that the level of narcosis caused by a 30-metre (100-foot) dive, whilst breathing air, is a comfortable maximum. The partial pressure of nitrogen at this depth on air is 316 kPa (3.16 bar) (Fraction of nitrogen x absolute pressure = 0.79 x 400 kPa). So, what fraction of nitrogen would cause the same narcosis at 60 metres? The answer is 45% nitrogen. (316 kPa/700 kPa) In technical diving, the equivalent air depth (EAD) is a way of expressing the narcotic effect of breathing gases such as trimix and heliox. ...

Nitrogen in a gas mix is almost always obtained by adding air to the mix.

Helium

Helium (He) is an inert gas that is less narcotic than nitrogen at equivalent pressure (in fact there is no evidence for any narcosis from helium at all), so it is more suitable for deeper dives than nitrogen. Helium is equally able to cause decompression sickness. At high pressures, helium also causes High Pressure Nervous Syndrome, which is a CNS irritation syndrome which is in some ways opposite to narcosis. General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Decompression sickness (DCS), the diver’s disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. ... HPNS, High Pressure Nervous Syndrome or Helium Tremors is a diving disorder caused by using breathing gases that contain helium at depths in excess of 130 metres / 429 feet. ...

Helium fills typically cost ten times more than an equivalent air fill.

Helium is not very suitable for dry suit inflation due to its poor thermal insulation properties — helium is a very good conductor of heat (compared to air which is a rather poor, making it more of an insulator). Helium's low molecular weight (monoatomic MW=4, compared with diatomic nitrogen MW=28) increases the pitch of the breather's voice, which may impede communication. This is because the speed of sound is faster in a lower molecular weight gas, which increases the resonant frequency of the vocal cords. Helium leaks from damaged or faulty valves more readily than other gases because atoms of helium are smaller allowing them to pass through smaller gaps in seals. It has been suggested that this article or section be merged with Wetsuit. ... The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer. ... These water valves are regulated by handles. ... Compression seal example A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage (eg. ...

Helium is found in significant amounts only in natural gas, from which it is extracted at low temperatures by fractional distillation. Natural gas is a gaseous fossil fuel consisting primarily of methane. ...

Neon

Neon (Ne) is an inert gas sometimes used in deep commercial diving but is very expensive. Like helium, it is less narcotic than nitrogen, but unlike helium, it does not distort the diver's voice. General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ... It has been suggested that this article or section be merged with Underwater diving. ...

Hydrogen

Hydrogen (H₂) has been used in deep diving gas mixes but is very explosive when mixed with more than about 4 to 5% oxygen (such as the oxygen found in breathing gas). This limits use of hydrogen to deep dives and imposes complicated protocols to insure that oxygen is cleared from the lungs, the blood stream and the breathing equipment before breathing hydrogen starts. Like helium, it increases the pitch of the diver's voice. See Exotic diving gases. Tech Diver Web. Retrieved on Jan 9, 2005. This article is about the chemistry of hydrogen. ... January 9 is the 9th day of the year in the Gregorian calendar. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ...

Unwelcome components of breathing gases

Many gases are not suitable for use in diving breathing gases. Here is an incomplete list of gases commonly present in a diving environment:

Argon

Argon (Ar) is an inert gas that is more narcotic than nitrogen, so is not suitable as a diving breathing gas. It is sometimes used for dry suit inflation by divers whose primary breathing gas is helium-based, because of argon's good thermal insulation properties. Argon is more expensive than air or oxygen, but considerably less expensive than helium. General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... Two divers, one wearing a 1 atmosphere diving suit and the other standard diving dress, preparing to explore the wreck of the RMS Lusitania, 1935 A diving suit is a garment or device designed to protect a diver from the underwater environment. ...

Carbon dioxide

Carbon dioxide (CO₂) is produced by the metabolism in the human body and causes carbon dioxide poisoning. Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ... Human anatomy or anthropotomy is a special field within anatomy. ... Hypercapnia is a condition where there is too much carbon dioxide (CO2) in the body. ...

Carbon monoxide

Carbon monoxide (CO) is produced by incomplete combustion. See carbon monoxide poisoning. Four common sources are: Carbon monoxide, with the chemical formula CO, is a colourless, odourless and tasteless gas. ... Combustion or burning is a complex sequence of chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ... Carbon monoxide poisoning occurs after the inhalation of carbon monoxide gas. ...

• Internal combustion engine exhaust gas containing CO in the air being drawn into a diving air compressor. CO in the intake air cannot be stopped by any filter. All internal combustion engines running on petroleum fuels contain some CO, and this is a particular problem on boats, where the intake of the compressor cannot be arbitrarily moved as far as desired from the engine and compressor exhausts.
• Heating of lubricants inside the compressor may vaporize them sufficiently to be available to a compressor intake or intake system line.
• In some cases hydrocarbon lubricating oil may be drawn into the compressor's cylinder directly through damaged or worn seals, and the oil may (and usually will) then undergo combustion, being ignited by the immense compression ratio and subsequent temperature rise. Since heavy oils don't burn well - especially when not atomized properly - incomplete combustion will result in carbon monoxide production.
• A similar process is thought to potentially happen to any particulate material, which contains "organic" (carbon-containing) matter, especially in cylinders which are used for hyperoxic gas mixtures. If the compressor air filter(s) fail, ordinary dust will be introduced to the cylinder, which contains organic matter (since it usually contains humus). A more severe danger is that air particulates on boats and industrial areas, where cylinders are filled, often contain carbon-particulate combustion products (these are what makes a dirt rag black), and these represent a more severe CO danger when introduced into a cylinder.

The internal combustion engine is an engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ... Exhaust gas is gas which occurs as a result of combustion of fuel such as gasoline/petrol, diesel or coal. ... A Diving Air Compressor is a gas compressor, which can fill diving cylinders with high pressure air that is pure enough to be used as a breathing gas. ... It has been suggested that this article or section be merged into Lubrication. ... After just three years of use dust has blocked this laptop heat sink, making the computer unusable Dust is a general name for minute solid particles with diameters less than 500 micrometers (otherwise, see sand or granulates) and, more generally, for finely divided matter. ... Humus is a word actually used for two different things, which are both related to soil and thus get used interchangeably. ...

Hydrocarbons

Hydrocarbons (C_xH_y) are present in compressor lubricants and fuels. They can enter diving cylinders as a result of contamination, leaks, or due to incomplete combustion near the air intake. Hydrocarbons are refined at oil refineries and processed at chemical plants A hydrocarbon is a chemical compound that consists only of the elements carbon (C) and hydrogen (H). ... Fuel is any material that is capable of releasing energy when its chemical or physical structure is changed or converted. ...

• They can act as a fuel in combustion increasing the risk of explosion, especially in high-oxygen gas mixtures.
• Inhaling oil mist can damage the lungs and ultimately cause the lungs to degenerate with severe emphysema.

Fuel is any material that is capable of releasing energy when its chemical or physical structure is changed or converted. ... The lungs flank the heart and great vessels in the chest cavity. ...

Moisture content

The process of compressing gas into a diving cylinder removes moisture from the gas. This is good for corrosion prevention in the cylinder but means that the diver inhales very dry gas. The dry gas extracts moisture from the divers lungs while underwater contributing to dehydration, which is also thought to be a predisposing risk factor of decompression sickness. It is also uncomfortable, causing a dry mouth and throat and making the diver thirsty. This problem is reduced in rebreathers because the soda lime reaction to remove carbon dioxide puts moisture back into the breathing gas. In hot, tropical climates, open circuit diving can accelerate heat exhaustion because of dehydration. A Diving Air Compressor is a gas compressor, which can fill diving cylinders with high pressure air that is pure enough to be used as a breathing gas. ... Corrosion is deterioration of intrinsic properties in a material due to reactions with its environment. ... Dehydration (hypohydration) is the removal of water (hydro in ancient Greek) from an object. ... Decompression sickness (DCS), the diver’s disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. ... A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycles exhaled gas. ... Soda lime is a mixture of chemicals, used in granular form in closed breathing environments, such as general anaesthesia, submarines, rebreathers and recompression chambers, to remove carbon dioxide from breathing gases to prevent CO2 retention and carbon dioxide poisoning. ... Hyperthermia is an acute condition resulting from excessive exposure to heat, it is also known as heat stroke or sunstroke. ...

Gas detection and measurement

Divers find it difficult to detect most gases that are likely to be present in diving cylinders because they are colourless, odourless and tasteless. Electronic sensors exist for some gases, such as oxygen analysers, helium analyser, carbon monoxide detectors and carbon dioxide detectors. Oxygen analysers are commonly found underwater in rebreathers. Oxygen and helium analysers are often used on the surface during gas blending to determine the percentage of oxygen or helium in a breathing gas mix. Chemical and other types of gas detection methods are not often used in recreational diving. An electro-galvanic fuel cell is an electrical device used to measure the concentration of oxygen gas in SCUBA diving and medical equipment. ... A carbon monoxide detector is a device that detects the presence of the toxic gas. ... A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycles exhaled gas. ... Air, oxygen and helium gas blending system Gas blending or gas mixing is the filling of diving cylinders with non-air breathing gases. ...

External links

• Dutch language fact sheet on Divox
• An online model of the partial pressure of oxygen