Breathing gas

As a breathing gas is called a gas mixture which is used for breathing with compressed air breathing apparatus ( breathing apparatus of the fire department, regulator and scuba diving). The use of breathing apparatus breathing gas is transported in compressed form in a compressed air bottle.

While in normal air breathing equipment solely for use will be used when diving mixtures both in the commercial sector as well as increasingly sophisticated scuba diving, in addition to the constituents of ordinary air also contain other components or that are composed entirely differently.

2.1 air
2.2 oxygen
2.3 Nitrox
2.4 Trimix
2.5 TRIOX
2.6 Heliair
2.7 Heliox
2.8 Neox
2.9 hydreliox
2:10 Hydrox

Continuous respiratory gas components and their meaning

The use of air differing mixtures are essentially two reasons that are related to the rising in increasing diving depth pressure:

Almost every gas can act from a certain gas pressure toxic to the human organism. This risk can be reduced by either the percentage (in the case of gas mixtures is generally calculated herein by partial pressure) reduces the component becoming dangerous or is entirely exchanged for a less dangerous in this compressed gas.
The higher the gas pressure, the greater the density of the breathing gas, which causes a " tougher " flow of the gas and thus an increase in the airway resistance. This can lead to fatigue of the respiratory muscles and thus to breathing problems.

Oxygen

Each breathe certain gas mixture must contain oxygen. When diving, it is assumed that - depending on the ambient and working conditions - oxygen from a partial pressure of about 1.4 bar (cold, heavy work ) to 1.6 bar (warm, no effort ) increasingly toxic to the central nervous system acts ( oxygen toxicity ), the risk increases disproportionately at even higher pressures and can enter the poisoning without warning suddenly.

Comparable with the inert gases is also breathing of oxygen under high pressure accumulation in the body instead, but this is limited to the nervous system (but obtained only when breathing mixtures with compared to air significantly increased oxygen content really meaning). This has the consequence that for oxygen desaturation times and residual saturations must be considered.

Inert gases

Regardless of the physical / chemical meaning of the word is understood in respiratory gases here under a gas which is not involved in the metabolic processes and serves only the dilution of the vital oxygen.

On the basis of the law of Henry dissolve in the course of the stay under increased pressure, the inert gases with increasing pressure intensified in the body tissue and enrich themselves. The speed and degree of saturation is strongly related to the type of tissue and its blood supply, where: The more blood supply, the faster and more go the gases in solution.

If the pressure is now reduced, the dissolved gases come back out from the tissues. Serves the pressure reduction ( for example, the emergence of ) too fast, the inert gases can not be removed with the blood and exhaled through the lungs, but pearls still in the tissue or blood from ( soda bottle effect), leading to life-threatening vascular blockages. To avoid decompression sickness, reducing stress, therefore, may be slow in a controlled decompression while maintaining the required decompression.

Nitrogen

Among the previously treated effects of nitrogen as inert gas occurs with increasing pressure on an increasingly intoxicating effect which may have from one person to completely different effects. These can range from anxiety or euphoria to unconsciousness and are generally grouped under the term rapture of the deep. For scuba divers, it is assumed that a partial pressure from 3.2 to 4 bar, which corresponds with air at a depth of approximately 30 to 40 m, can be expected with the onset of symptoms. However, the susceptibility depends on so many factors such as mood, form on the day, environmental conditions, et cetera from that must never be assumed that a diver who showed symptoms until now or never, for example, only from 50 m, this is not suddenly at 30 m already can do.

This effect of nitrogen is the main reason that for scuba divers with ordinary compressed air 40 m is recommended as a reasonable maximum depth of diving. In addition, information can also be found under decompression sickness.

Helium

Helium is by nitrogen, the most common - dilution gas used in breathing mixtures and has in his role as an inert gas also, the above discussed effects - mainly in the technical and commercial diving. Due to its small atomic size, however, both the solution in the tissue as well as the desaturation takes place faster than in nitrogen. This higher mobility (diffusion) has paradoxically actually an extension of the decompression result, since the pressure must be reduced much more carefully than in nitrogen, to prevent a bubble out of the fast from the tissues into the blood passing helium.

Also, helium has been making in greater depth an effect on the central nervous system, which in the so called High Pressure Nervous Syndrome ( HPNS, colloquially " helium tremors " ) noticeable. The main reason for the process of compression of the nerves is connected with the influence of helium, the speed plays a crucial role: With the typical technical diving Abtauchgeschwindigkeiten can be expected from a range of 150 to 200 m with the onset of symptoms, while in the very slow increase in pressure in the commercial diving depths up to 600 m can be achieved without effect. Other properties of helium over nitrogen are:

A lower density, which is considerably lower at the same pressure of the breathing resistance.
A higher thermal conductivity. Therefore, helium mixtures may not be used as Tariergas for a dry suit. Usual filling gases for dry suits are air or argon better.

Neon

Neon is a component rarely used. It is considered expensive, it also has a higher compared with helium breathing resistance. It also acts as an inert in the sense described above.

Hydrogen

Hydrogen is also an exotic component that comes very rarely in extreme deep dives used. It also acts as an inert in the sense described above.

Names of common respiratory gas mixtures during the dive

Air

Air (compressed air) is the most common respiratory gas mixture, and is simplified viewed from 79% nitrogen and 21% oxygen as well as residues of carbon dioxide and noble gases. The limits for recreational divers for diving with air are by the narcotic effect of nitrogen at recommended 40 m. At the latest in the range of about 60 to 70 m makes the additional danger of oxygen toxicity risk not calculable.

The dive attempt by a former companions Cousteau with air to about 130 m was fatal.

Oxygen

Pure oxygen is used in technical diving as a decompression gas, to shorten the decompression. The operating depth is limited in theory to the last deco stops at 3 to 6 m.

A special application is the use in oxygen rebreathers ( rebreather ).

Nitrox

Nitrox is a mixture of nitrogen (English Nitrogen) and oxygen ( engl. Oxygen). The oxygen content of the Nitroxgemisches varied according to requirements and intended use. The most common use of Nitrox mixes have an oxygen content of 32 to 40%. Due to the reduced amount of nitrogen the risk of decompression illness is lowered. However, the increased risk of oxygen toxicity limits the maximum depth.

Trimix

Trimix is a mixture of oxygen, nitrogen and helium and is also deep, used for technical diving depths to 200 m, in commercial diving.

TRIOX

Triox is a normoxic mixture of oxygen, nitrogen and helium and is used for diving up to 60 m. Available mixtures are 30/30 = 30% oxygen, 30 % helium and 40% nitrogen ( for immersion up to 40 m ) and 21/35 = 21% oxygen, 35 % helium and 44 % nitrogen. TriOx is also called normoxisches Trimix.

Heliair

Heliair is a mixture of helium and air, and is the same use as Trimix.

Heliox

Heliox is a mixture of helium and oxygen ( Oxygen), which is used in commercial diving depths in large to very large (600 m).

Neox

Neox is a mixture of neon and rarely used oxygen ( Oxygen). The mixture is considered to be expensive.

Hydreliox

Hydreliox is a mixture of hydrogen (hydrogen), helium and oxygen ( Oxygen) and is similar to helium mixtures. The explosivity of the oxygen -hydrogen mixture can be maintained by suitable mixing ratio below the explosive limit and suppresses it.

Hydrox

Hydrox is a mixture of hydrogen (hydrogen) and oxygen ( Oxygen), which is used for extreme dives (1992 Fa COMEX 701 m in a pressure chamber, 534 m in the open water). Due to the explosive nature of oxygen - hydrogen mixture, this mixture can be used only from depths at which the oxygen partial pressure is below the explosion limit.

Special cases

Liquid breathing - only tested on a laboratory scale opportunity with benefits during withdrawal ( decompress ) to see.
Artificial gills - just as futuristic to be seen method discussed can be seen in the context of Homo aquaticus.

Diving regulator Underwater diving Recreational diving Inertgas Trimix (breathing gas) Flammability limit Hydrox (breathing gas)

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