Regs for Deco/Stage Bottle

[nereas]

I'm not certain about the 140' thing, but I'm pretty darn sure that 30/30 is GUE's standard trimix mix, for better or worse...

140/33 + 1 = 5.24 ATAs

5.24 ATAs x 30% = 1.57 ATAs ppO2. This is safe and conventional as a deco mix since it is below 1.60 ATAs.

TMX 30/30 is a great mix for deco in the range of 140 fsw to 70 fsw.

The next leaner deco mix that I like is TMX 20/40 for deco in the range of 200 fsw to 150 fsw. However this is a personal preference. I also use this gas a lot as a backgas for diving in the range of 100 fsw to 200 fsw as well.

TMX 20/40 also serves as a great travel mix when you need one, since for that it works well from the surface down to 200 fsw.

Those then are my own 4 favorite deco mixes:

TMX 20/40
TMX 30/30
EAN 50
100% O2.

CompuDude, normally you will train first with EAN 50. The next deco gas that is added is usually O2. Then others progressively.

 

[limeyx]

It's "A" GUE standard mix, certainly not the only one! That said, the few GUE Tech 1 divers I know don't bother with it (most prefer either 21/35 or simply 32% for the relevant depths).

In any case, what deco classes are you training for that require you to sling a 40 at this point?

30/30 is good for long "shallow" deco dives (say a long dive @ 100 feet)
Official "MOD" is 100 feet "average" -- I use it very rarely if there is a reef or wreck between 100 and 120. It's a pain to mix and not especially cheap.

If I am going to go into mandatory deco, I would probably prefer 30/30 or even (shock horror) the non-GUE standard 25/25, as you need all the "help" you can get when you cant just ascend to the surface at 10fpm

The GUE standard mixes are published in a number of places
32%, 30/30 100 feet
21/35 150-160ish (150 average)
18/45 200
15/55 ...

 

[limeyx]

140/33 + 1 = 5.24 ATAs

5.24 ATAs x 30% = 1.57 ATAs ppO2. This is safe and conventional as a deco mix since it is below 1.60 ATAs.

TMX 30/30 is a great mix for deco in the range of 140 fsw to 70 fsw.

The next leaner deco mix that I like is TMX 20/40 for deco in the range of 200 fsw to 150 fsw. However this is a personal preference. I also use this gas a lot as a backgas for diving in the range of 100 fsw to 200 fsw as well.

TMX 20/40 also serves as a great travel mix when you need one, since for that it works well from the surface down to 200 fsw.

Those then are my own 4 favorite deco mixes:

TMX 20/40
TMX 30/30
EAN 50
100% O2.

CompuDude, normally you will train first with EAN 50. The next deco gas that is added is usually O2. Then others progressively.

For deco for GUE, standard gases would be.



190: 21/35
120: 35/25
70: 50% nitrox (possibly 50/25 trimix for long dives or where you are in a cave and want the bottle to float a little better full -- esp with an AL80)
20: 100%

(although for the mixes with He, usually these are just minimums for GUE, it's better to be a bit over than under). For the bottom mixes, again generally the O2 numbers are max, and the He min -- it's (to an extent) OK to have a bit less O2 and a bit more He.

 

[Rainer]

30/30 is good for long "shallow" deco dives (say a long dive @ 100 feet)
Official "MOD" is 100 feet "average" -- I use it very rarely if there is a reef or wreck between 100 and 120. It's a pain to mix and not especially cheap.

If I am going to go into mandatory deco, I would probably prefer 30/30 or even (shock horror) the non-GUE standard 25/25, as you need all the "help" you can get when you cant just ascend to the surface at 10fpm

The GUE standard mixes are published in a number of places
32%, 30/30 100 feet
21/35 150-160ish (150 average)
18/45 200
15/55 ...

25/25 appears to fill a void in the GUE standard gasses (namely 100-120'). Seeing as it can (almost) be blended from 32%, offers deco advantages over 30/30, and given 30/30 now is only for dives to 100' (used to be 120', but that's nearly 1.4 PPO2), I'm surprised that GUE hasn't endorsed something like 25/25. Sure, I get the political issues associated with this being AG's gas, but come on... Also makes taking Rec TriOx much less appealing. As I read some of MHK's old posts, this used to be a class for recreational divers wanting to safely dive deeper (to 120'), not I just don't see the point. Think I'll just practice and wait for Tech 1.

 

[limeyx]

25/25 appears to fill a void in the GUE standard gasses (namely 100-120'). Seeing as it can (almost) be blended from 32%, offers deco advantages over 30/30, and given 30/30 now is only for dives to 100' (used to be 120', but that's nearly 1.4 PPO2), I'm surprised that GUE hasn't endorsed something like 25/25. Sure, I get the political issues associated with this being AG's gas, but come on... Also makes taking Rec TriOx much less appealing. As I read some of MHK's old posts, this used to be a class for recreational divers wanting to safely dive deeper (to 120'), not I just don't see the point. Think I'll just practice and wait for Tech 1.

Not an argument from me. The GUE standard gases are pretty good in general I think, but also the concept of a standard gas set is I think as (or more important) than the actual gases you choose (as long as they are chosen sensibly, with good reason and all fit together).

I have no issues diving 25/25 to 120, but I would rather not (say) dive something like 26/17 to 150 etc. 25/25 fits the GUE model pretty closely, but other choices do not, and I avoid those.

 

[nereas]

25/25 appears to fill a void in the GUE standard gasses (namely 100-120'). Seeing as it can (almost) be blended from 32%, offers deco advantages over 30/30, and given 30/30 now is only for dives to 100' (used to be 120', but that's nearly 1.4 PPO2), I'm surprised that GUE hasn't endorsed something like 25/25. Sure, I get the political issues associated with this being AG's gas, but come on... Also makes taking Rec TriOx much less appealing. As I read some of MHK's old posts, this used to be a class for recreational divers wanting to safely dive deeper (to 120'), not I just don't see the point. Think I'll just practice and wait for Tech 1.

If I were planning a dive to 150 fsw, with no chance of going deeper, I would choose TMX 25/35. This mix offgasses more efficiently with EAN 50 than does 25/25 because 25/25 contains more nitrogen.

The only thing I do not like about 25/xx is that it gives you little or no flexibility beyond 150 fsw. That is why most of my dives to 150 fsw end up with TMX 20/40 instead, which gives me additional flexibility all the way down to 200 fsw.

For most of the pinnacles that I dive, the range of depth can be anywhere from 150 to 200 fsw. I never really know exactly what my buddies are going to be up for on any given day. They are not that analytical. And most of them dive a 21/xx trimix blend anyway.

 

[Rainer]

GUE dives standard gases, not best mix.

 

[scubawally]

there are a few different schools of though on this subject... First in my opinion there is no need to use a reg that has not been made by scubapro so in my opinion if you are using SP for you back gas also use them for any stage or deco bottles that you have.

REG PERFORMANCE

there are two schools of thought when it comes to selecting the quality of reg that you are going to use on your deco bottle. The first states that when you are using a deco bottle you are in relatively shallow water and it is easier to breath from any reg in shallow water there for a introductory level reg (mk2+/r-190) will still work fine...I agree with this as I have dove with that reg config and it works fine I use it for my O2 deco bottle. The other school of thought is that you will possibly be breathing from this reg longer than you would from your back gas (this can easily be the case for very deep and long technical dives) and therefore you need to get a reg that will breath the easiest (MK25/S600) which one you decide on will partially be dependent on how long you use your deco bottle. If you want it as primarily a source of redundancy and dont plan on doing hours of deco the cheaper reg set might be your best option.

IN addition even thought the EPDM O-rings supplied in the annual service kits for all SP regs are O2 compatible not all of the reg sets have dedicated O2 servicing kits.

some divers (ones that service their own gear) like to have the smallest number of different regs possible to minimize the number of spare parts kits that they have to carry on long diving excursions. If you take your regs to the shop for service this is less of a problem.

hope that this helps you out`