Triox, Trimix and Heliox question.

[LiteHedded]

Yes. Same reason for trimix at deeper depths ... to control narcosis. GUE standard gas for 110-150' is 21/35.

it's also handy for making heavy payloads lighter

 

[ScoobaChef]

I wouldn't get too caught up in the specifics. I never call anything triox or helitrox (and I don't really know anyone who does, either), regardless of o2 content. Its all just simply trimix to me

I know what you mean, pretty much everyone around here refers to all of it as trimix, but since GUE's required reading uses the references, i figure it's good to at least have a basic understanding of what they're referring to.

 

[Teller]

I wouldn't get too caught up in the specifics. I never call anything triox or helitrox (and I don't really know anyone who does, either), regardless of o2 content. Its all just simply trimix to me

I agree. TMx is TMx. I have never used a gas with only O2 and He though.

 

[ScoobaChef]

Yes. Same reason for trimix at deeper depths ... to control narcosis. GUE standard gas for 110-150' is 21/35.

DH,

I was thinking more extreme like a 21/79 mix. Sure, you would pretty much eliminate narcosis at shallower depths but at an enormous cost.

I haven't sat down and worked it out, but wouldn't using such a mix push your NDL far beyond what you could reasonably hope to carry.

-for the purpose of discussion, I'm referring to OC not CCR

 

[waterpirate]

Ok so to sum it all up in "descending" order

-triox and helitrox refer to a hyperoxic trimix blend which gives you a shallower END than nitrox with an identical O2 content. (Though the MOD stays the same)

-trimix, while somewhat a catchall term, typically refers to normoxic or hypoxic blends of O2, helium and nitrogen used for deeper diving.

-heliox is O2 and helium only, mainly reserved for very deep dives to eliminate nitrogen narcosis.

Have I got it right?

Just out of curiosity, because I know it would be a huge waste of money and helium, but is there anybody out there who uses hyperoxic heliox for dives above 150 fsw? If so, why?

Since I started mixing my own gas I dive tmx all the time. 32/20, 28/20, 25/20, 18/45. I love He.
Eric

 

[ScoobaChef]

Since I started mixing my own gas I dive tmx all the time. 32/20, 28/20, 25/20, 18/45. I love He.
Eric

Eric,

How are the He prices up there? I'm originally a jersey boy, so I hope to get back and do some diving up there. My lds is charging roughly $300 to fill ld100 twins with 32/20.

 

[gsk3]

I was thinking more extreme like a 21/79 mix. Sure, you would pretty much eliminate narcosis at shallower depths but at an enormous cost.

How are the He prices up there? I'm originally a jersey boy, so I hope to get back and do some diving up there. My lds is charging roughly $300 to fill ld100 twins with 32/20.

Around $1/cuft of He.

Heliox (no N2) is pretty much a medical gas. Even for extremely deep dives I believe they add in a little N2 to avoid the risk of HPNS.

 

[PfcAJ]

DH,

I was thinking more extreme like a 21/79 mix. Sure, you would pretty much eliminate narcosis at shallower depths but at an enormous cost.

I haven't sat down and worked it out, but wouldn't using such a mix push your NDL far beyond what you could reasonably hope to carry.

-for the purpose of discussion, I'm referring to OC not CCR

You still have to deco from helium gases, but the total deco times really aren't that much different between helium and nitrogen based gases (maybe a few minutes here and there, depending on the algorithm).

 

[Bombay High]

Around $1/cuft of He.

Heliox (no N2) is pretty much a medical gas. Even for extremely deep dives I believe they add in a little N2 to avoid the risk of HPNS.

Commercial divers use Heliox exclusively for saturation diving. The risk of HPNS is offset by very gradual compression. I have done dives on HELIOX 2/98 deep mix and not experienced HPNS. it can still affect you, and some are more susceptible than others. If you do experience it, you are off the dive. The mix will not change.

 

[waterpirate]

Eric,

How are the He prices up there? I'm originally a jersey boy, so I hope to get back and do some diving up there. My lds is charging roughly $300 to fill ld100 twins with 32/20.

I pay .42 a cubic foot, and was warned about the price increase last spring and pre-bought T's to last me this season, lol. I am paying 18.00 a T for ultra pure 02. So a fill is really cheap for me.
Eric