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You need ~0.2 Bar of oxygen partial pressure. The purpose of Trimix/Heliox is to keep oxygen partial pressure under 1 Bar while also reducing nitrogen to preven
by lokopodium 8y ago
You need ~0.2 Bar of oxygen partial pressure. The purpose of Trimix/Heliox is to keep oxygen partial pressure under 1 Bar while also reducing nitrogen to prevent narcosis. You can't breathe the 200m mix at sea level pressure.
- jsjohnst 8y ago> You can't breathe the 200m mix at sea level pressure. What makes you think you can’t (other than it being hypoxic)? You most certainly can breath Heliox, in fact, it has been used medically[0] for almost 100 years, far longer than used for commercial diving. [0] https://en.m.wikipedia.org/wiki/Heliox https://en.m.wikipedia.org/wiki/Heliox
- johncolanduoni 8y agoHeliox doesn’t denote a specific concentration of helium and oxygen; even just within diving the mix varies depending on the depth it is to be used at.
- jsjohnst 8y agoCorrect! A common ratio for deep diving is 12/88, but 21/79, 30/70 and 40/60 are also used at less depth. In fact, Heliox would usually not be used for dives to 200m due to HPNS risk. Usually it would be Trimix for that. Either way, GP is mostly wrong on the points they made.
- jsjohnst 8y agoAlso, the oxygen partial pressure you need to stay under is 1.6 Bar for oxygen toxicity. Huge difference between 1.0 and 1.6, depending on oxygen percentage, the difference could be a >50% reduction in MOD.
- ConceptJunkie 8y agoThank you for spelling "breathe" correctly. It seems these days I see it spelled wrong more than I see it spelled correctly.