Advantages of Trimix?

[Rainer]

That's not the case at all. Kim's point that you quoted was discussing nitrox, not trimix.

You'll have less NDLs on 21/35 than 32-36% nitrox. Now, you could have *similar* NDL times on 30/30 (say compared to 32%) and a clearer head at those depths. I personally make the switch to trimix past about 110' to mitigate narcosis.

So please let me ask this... Since I have a dive that keeps me at 100' (98'-103') I am quite curious about this as I have not given it any though until now (thanks ScubaBB)... I am usually around 34% but even at 36% I can only stay a max of 35 minutes according to PADI or Navy tables. (thats off the top of my head)

If I am reading what yall are saying correctly then I should be able to increase my bottom time going with a 21/35... If this is true, how significant of an increase in time could I see diving at 100'...?

Thanks, lee

 

[lsorenson]

That's not the case at all. Kim's point that you quoted was discussing nitrox, not trimix.

You'll have less NDLs on 21/35 than 32-36% nitrox. Now, you could have *similar* NDL times on 30/30 (say compared to 32%) and a clearer head at those depths. I personally make the switch to trimix past about 110' to mitigate narcosis.

Thanks Rainer... After reading a couple of pages I started skimming... Thanks for pointing that out!

lee

 

[wedivebc]

Try this simple experiment sometime ... go on a dive to 30-35 meters with someone who is trimix certified. You take air or up to EAN32 ... your buddy takes a trimix with 20% to 25% helium. At maximum depth, breathe off your buddy's spare regulator for about a minute.

All will become clear ...

... Bob (Grateful Diver)

Would that then be trymix?

 

[DiveNav]

........ I am usually around 34% but even at 36% I can only stay a max of 35 minutes ......
If I am reading what yall are saying correctly then I should be able to increase my bottom time going with a 21/35... ...

I don't have the simulator open right now .... but, depending on the mix - and your dive profile, Trimix could get you into deco even sooner ..... but it will also get you out from deco faster

 

[DuboisP]

i don't dive trimix, but my understanding is you have the three gasses, Nitrogen, Helium, Oxygen in a tank. Those three gasses can be put into the tank in whatever proportion you feel like.
Normally the setup is normoxic (21% O2, which allows a depth of 56M at 1.4PP02, XX% N2, and the remainder Helium), but if you are going deeper than 60 M you may look at taking multiple mixes, including hypoxic (< 21% O2, a small amount of N2 and the remainder He) as a bottom gas, and a separate mix for deco, which may have more than 21% O2 (hyperoxic) . Someone feel free to correct me, if my understanding is incorrect.

speaking physiological, 16% is also normoxic
depending diving agencies, it will be 17% or 18%

 

[DA Aquamaster]

I don't have the simulator open right now .... but, depending on the mix - and your dive profile, Trimix could get you into deco even sooner ..... but it will also get you out from deco faster

Right, but specific depths and times matter.

To greatly oversimplify, helium is a "faster" gas than nitrogen so you on gas it quicker but you also off gas it quicker as well. So faster tissues will saturate quicker, shortening the NDL at some depths while on longer deco dives where the faster tissues are saturated anyway, the slower tissues will off gas faster reducing the deco compared to air.

Consequently some shorter profiles tend to penalize you for trimix while longer profiles tend to get you out of the water sooner with trimix.

The percentages of He and O2 obviously have an effect on the deco obligation with trimix, but not as much as you'd think - what drives those numbers in gas selection are the maximum END desired and the max PO2 desired in the deepest working portion of the dive.

 

[Rhone Man]

Point being that the prupose of nitrox isn't to reduce narcosis, as the person I was quoting said. But, you already knew that

Yeah; I was just thinking though: we all have the deep air debate pretty regularly on SB (I schedule it as a quarterly event on my calendar), but we seem to have the "how narcotic is O2" debate far less frequently.

Just sayin'.

 

[VooDooGasMan]

Well said DA, sometimes I,m ask why air, and it takes a bit, that is Darn well said.

 

[cool_hardware52]

Heart a lot about Trimix lately. I'm always interested in learning new things about diving. Can somebody explain me what are the advantages of diving with Trimix?

A few other points to consider.

While there may be some limited applications for Trimix and single cylinders in most cases TriMix means doubles and some accelerated decompression gas or gases.

The depths where Trimix becomes useful or necessary are deep enough that the redundancy of doubles is worth considering, and the volume of gas that doubles can provide is necessary to carry adequate reserves.

Using doubles of course carries creates new risks along with the benefits, managing failures and enough gas to incur large deco obligations.

In short my advise would be to educate yourself about gas planning and decompression requirements for diving beyond ~100 ft before you grab a single 15L tank and go see what Trimix is all about.

Tobin

 

[Ste Wart]

Yeah; I was just thinking though: we all have the deep air debate pretty regularly on SB (I schedule it as a quarterly event on my calendar), but we seem to have the "how narcotic is O2" debate far less frequently.

Just sayin'.

It's a moot point. No one can prove it's more narcotic, in theory (overton -meyer?) it looks twice as narcotic as Nitrogen. But it's apples & oranges, one is an inert gas the other metabolised. Can the 2 really be compared?

I mean there's a fair few of us that have deco'd on pure O2 at 6m (pp 1.6) anyone significantly off their chops during their deco?