Editing Trimix (breathing gas) (section)

====Heliair====
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'''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. This term, first used by [[Sheck Exley]],<ref name="bowen" /> is mostly used by [[Technical Diving International]] (TDI).

It is easily [[gas blending|blended]] from helium and [[air]] and so has a fixed 21:79 ratio of oxygen to nitrogen with the balance consisting of a variable amount of helium. It is sometimes referred to as "poor man's trimix",<ref name="bowen" /><ref name="gentile" /> because it is much easier to blend than trimix blends with variable oxygen content, since all that is required is to insert the requisite [[partial pressure]] of helium, and then top up with air from a conventional compressor. The more complicated (and dangerous) step of adding pure oxygen at pressure required to blend trimix is absent when blending heliair.

Heliair blends are similar to the standard Trimix blends made with helium and Nitrox 32, but with a deeper END at MOD.
Heliair will always have less than 21% oxygen, and will be hypoxic (less than 17% oxygen) for mixes with more than 20% helium.