Breathing Gas

Breathing gas is a mixture of gaseous chemical elements and compounds used for respiration.

Air is the most common and only natural breathing gas. Other 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, medical life support and first aid equipment, high-altitude mountaineering and anaesthetic machines.

Most breathing gases are a mixture of oxygen and one or more inert gases. Other breathing gases 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.

A safe breathing gas for hyperbaric 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 in breathing gases. There are many other possibilities.
  • 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.

Read more about Breathing GasCommon Diving Breathing Gases, Unwelcome Components of Breathing Gases, Moisture Content, Gas Detection and Measurement

Other articles related to "breathing gas, gas, breathing":

Breathing Gas - Gas Detection and Measurement
... 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 ...
Argox - Possible Uses - Drysuit Inflation
... The helium in the breathing gas trimix, which is used to avoid nitrogen narcosis on deep dives, gives the gas a high thermal conductivity compared with air ... Divers breathing trimix with drysuits usually inflate their drysuits with their decompression gas (usually nitrox or oxygen) ... blend with oxygen content similar to that of air could be used as a suit inflation gas in place of pure argon, as such a blend would only have a slightly higher thermal conductivity than pure argon ...
Decompression Algorithms
... Breathing gas is supplied at the same pressure as the surrounding water, and some of this gas dissolves into the diver's blood and other fluids ... Inert gas continues to be taken up until the gas dissolved in the diver is in a state of equilibrium with the breathing gas in the diver's lungs, (see "Saturation diving"), or the diver ... of the diver if the partial pressure of the gas in the diver gets too high when compared to the ambient pressure ...
Pony Bottle - Breathing Gas
... A general rule of gas usage in this range is that the "bailout gas should match existing breathing gas" ... Often in boats gas refills to these higher limits are not possible, so it is important that pony be filled prior to the dive trip excursion ...
Fully Redundant Alternative Air Sources - Bailout Bottle - Bailout Cylinders For Use With Surface Supplied Equipment
... commercial diving using surface supplied breathing gas, the bailout cylinder is in many cases required by health and safety legislation and approved codes of practice as an obligatory component of the ... the intention is that the bailout cylinder should hold sufficient breathing gas for the diver to be able to reach a place of safety where more breathing gas is available, such as the ... To achieve this the cylinder must contain enough gas to allow decompression if that is included in the planned dive profile ...

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