Trimix vs Helitrox

[Patoux01]

Mate, just quit. Honestly just quit.

---------- Post added May 5th, 2015 at 09:43 PM ----------

Oh, and you should consider looking up "narcosis" in that book of yours.

 

[Rich Keller]

Mate, just quit. Honestly just quit.

---------- Post added May 5th, 2015 at 09:43 PM ----------

Oh, and you should consider looking up "narcosis" in that book of yours.

So I should ignore what the people who invented trimix have to say about it? The reason for the nitrogen in the trimix is that the effects of narcosis reduces or elimates the effects of HPNS. Maybe you should be the one to do a little more reading.

 

[Patoux01]

So you're advocating heliox for every diver starting at 150feet...

 

[oldschoolto]

Large popcorn ... Please....

 

[Basking Ridge Diver]

I have no dog in this fight - but Deco for Divers suggests - Trimix - Normoxic mixes 18-21% O2 to 60 m, Hypoxic with less than 18% O2 - travel gas - but gives no range (but I am assuming deeper than 60 m based on the mix) and Hyperoxic more than 21% O2 to 30 up to 55 meters.

Chatterton teaches advanced Trimix - "I like to go a little beyond the minimums and provide students with some additional training, experience, and insight that I feel is important for divers who are planning and executing deep open circuit Trimix dives. Students who successfully complete this training should be able to competently plan and conduct decompression dives on Trimix, up to the TDI depth limit of 330 fsw, under similar conditions, using similar equipment."

So I would expect you can go lower - no? Or is 330 fsw the floor?

 

[ajduplessis]

Definitely on crack and a lot of it.

 

[kr2y5]

I realize this is probably a little bit off topic w.r.t. the Trimix vs Helitrox discussion, and perhaps the mod can move that whole subthread elsewhere, but purely out of curiosity, I'm interested in the basis of the earlier claim that Trimix is not needed until 430ft. Regardless of whether this is true or not, it was probably prompted by some interesting experiences that might be worth learning about.

 

[ajduplessis]

You should smoke crack and read the US Navy Diving Manual. Its all there.

 

[Redshift]

I think there is being some misunderstanding here. Trimix is not needed above 430ft because then what should be used is heliox. The nitrogen is later introduced to reduce HPNS.
I guess there is nothing preventing a trimix certified diver to get a heliox mix... but it would be really expensive and have a great impact on body temperature.
What is being discussed here is not the mix itself. It's the having helium in the mix, the certification depths, needed skills and equipment and risk. That's why courses are broken down into several. In this case there is an introductory decompression course that may or not involve helium in a limited manner. Followed by a normoxic course that increases depth, task load and planning, and finally hypoxic where there in addition to the implications coming from the greater depths, there is also the clear change of having a bottom gas not breathable at the surface.

 

[tomfcrist]

Trimix only real use is to reduce or eliminate the effects of HPNS in saturation divers. Read it for yourself genius. Military: US Navy Diving Manual (6th Edition) You use a higher percent of nitrogen then is needed only to reduce the cost of a fill vs heliox and you think it sounds impressive when you tell people you dive trimix.

Well Rich, I guess if you consider heliox a better suited gas, that's fine. In my humble opinion, there is no need for heliox for 99.9999% of tech divers. Why? Lets look at a dive to 300ft for 20 minutes using just 50% and 100% for deco.

If you dive AIR.. you are at a 2.12PPO2 which I don't think anyone believes is a wise decision....thus we add helium. Now we can either go straight Heliox at say 12/88 or we could use a trimix that keeps our PPO2 down and our Narcotic depth around 100fsw....for ****s and giggles, lets say 12/55. Lets also assume we are running Buhlmann at GF 40/75.

Heliox=292 runtime
Trimix=168 runtime

So before you go spouting off about how smart you are, or posting a link to the Navy Dive Manual(which I am very familiar with), maybe you should sanity check yourself.