Standard MOD

[iztok]

This is just out of curiosity as I see UTD and GUE use a lot of standard gases and label deco gases by MOD.

When you label MOD what ppO2 are you using for it in DIR? 1.6 or 1.4 or something else?

So for 50% would MOD be 70 (ft) or?

I am assuming it is 1.6 and

50% - 70
80% - 30 (not even sure this is a standard gas)
100% - 20

Just trying to understand things bit better. Slowly

 

[Captain12Pk]

Your understanding of this is correct. DECO gasses are planned with a 1.6 in mind... 50% @ 70fsw, 100% @ 20fsw.
No, 80% is not a standard gas for any agency I'm aware of.
The only difference would be your back gas. In most cases, yor back gas is planned with a 1.4, or even a 1.2.

 

[Rainer]

Only shallow deco gases are planned at 1.6.

Backgas is planned at 1.4 or lower.

 

[ucfdiver]

To add to what Rainer said, most people I dive with tend to plan 1.2ppo2 average or less, and 1.4 as a max. OxTox is perhaps the most dangerous situation any technical diver can find themselves in, so we don't take it lightly.

 

[rjack321]

To add to what Rainer said, most people I dive with tend to plan 1.2ppo2 average or less, and 1.4 as a max. OxTox is perhaps the most dangerous situation any technical diver can find themselves in, so we don't take it lightly.

Not only that but the benefits of maxing out the ppO2 on the bottom are not very substantial (generally 5-10mins less deco). Doing more deco is always easier than toxing.

MODs on deco gases are 1.6 except when you're using a really deep one like 21/35 @ 190ft where 1.6 is not helpful anyway and just jacks up your CNS% for the rest of the dive.

MODs on bottom gases are 1.4 although they typically only used at 1.0 to 1.2 - basically there's a buffer between the labeled max use depth and the practical/actual use depth.

 

[ianr33]

MODs on bottom gases are 1.4 although they typically only used at 1.0 to 1.2 - basically there's a buffer between the labeled max use depth and the practical/actual use depth.

But they would be LABELED with the MOD for 1.6 ,even though you would not choose to actually dive them that deep?

 

[amascuba]

But they would be LABELED with the MOD for 1.6 ,even though you would not choose to actually dive them that deep?

Bottom gases don't need to be labeled as the mix should be appropriate to the dive to begin with.

 

[ucfdiver]

But they would be LABELED with the MOD for 1.6 ,even though you would not choose to actually dive them that deep?

Labeled 1.4. Often I'll do quick dips to even 115ft on 32% (it's not DIR, but most DIR guys I know do this) in the back of the cave, since 95% of it is 70-80ft. Once that higher exposure grows, I'll quickly lean out the mix with other standard gases.

Bottom gases don't need to be labeled as the mix should be appropriate to the dive to begin with.

That's highly debatable, and can be deadly in a team environment. When setup divers breathing a shallower back gas are brought into the picture, the potential for getting on the wrong bottle grows, since these bottles are shared, so even names on them don't mean a whole lot. I would prefer sticking to a unified system that works in as many environments as possible, not just off boats and smaller cave dives, but for MOST divers, I can see that working.\

White tape and a thick sharpie to clearly label the gas can be bought for <$10. This even works on boats where you're topping off for shallower dives, so I'm not sure what reason you'd have for not labeling any gas in the water.

 

[LiteHedded]

Bottom gases don't need to be labeled as the mix should be appropriate to the dive to begin with.

silliness IMO

 

[iztok]

I didn't want this to be another labeling or not back gas debate. I was not too clear that I was looking for deco gasses info.

Sorry if I stirred up something. It was not my intention.