To Nitrox or not to nitrox ,Why and how ?

[Searcaigh]

LOL yes I did. Teach me to sit in a parking lot and type on a computer. Should have been working anyway

Yes it lengthens the NDL and shortens the SI. Thank you for pointing that out

Thought you would be eating donuts

 

[Searcaigh]

NITROX is a great gas for a photographer, love the stuff for any dive from 15-30M

 

[doctormike]

Nitrox reduces the percentage of nitrogen in a given mix at a given depth.

The percentage does not change with depth.

I'm gonna stick with "wrong".

Yup. The percentage does not change with depth. That seems to be consistent with what waterpirate is saying.

I would rephrase it as "Nitrox gives you a reduced percentage of nitrogen when compared to air. This is true at any given depth, since the percentages do not change with ambient pressure."

Wow, I must be really bored to care about this... gotta get back to work!

 

[Tortuga68]

Perhaps what WP meant was "at any given depth"

Actually, I think that you may be misinterpreting waterpirate's statement. Although the term "nitrox" is inexact (it could technically refer to any mix - hypoxic, normoxic or hyperoxic), I assume that he is using it to refer to mixes with more than 21% O2 (i.e EAN, or enriched air nitrox)

Yes that's why using the term EAN is more appropriate in most (recreational) Nitrox discussions

 

[BTravlin]

OK --Im liking the sound of longer bottom time especially at some of our local dives. I suspect its a waste of time for vacation diving given the first diver in the group that signals they are low on air thumbs the dive for the group anyway

You need to find a better vacation dive op then. I dive Cozumel regularly and our dive time, at least with my favorite op, is dictated only by our remaining gas and NDL's. We do multiple dives per day for a week and the Nitrox is great for extending our bottom time.

 

[tufb98]

I would add two comments about the use of EANx that I did not see mentioned (if I missed something someone said I apologize).

1. Does using it REALLY make a difference where you are diving? For example, if you are on a reef wall where can you see the same things (with better light) above 60ft as below, you might forgo and just dive shallower.

2. If you are diving with a group (and you want to stay with the group) is the group using EANx? If they are not then, there really is not a need for it.

 

[doctormike]

Perhaps what WP meant was "at any given depth"

Exactly...!

To rewrite it, I would just leave off the reference to depth altogether, since as professor Dalton noted in 1801, the relative proportions don't change with pressure - assuming ideal gasses that don't react with each other, and aren't being subject to extremely high pressures at which molecular diameter enters into the calculations.

Thank you all for giving me this opportunity to procrastinate. Back to work.

 

[BoltSnap]

It seems that most posts here (if not all) are emphasizing the "Decompression Advantage" of using EAN (longer Dive Time and/or shorter SI) but not the "Physiological Advantage." I don't use EAN to push the NDL or make shorter SI, instead, I use it with air 21% O2 NDL limits as added measure of conservatism. Provided my gas supply is sufficient, I may push the "Air" NDL limit but I am still well within the respective NDL for the EAN.

 

[Tortuga68]

That's probably because there isn't any scientific evidence for the physiological advantage

If it works for you, more power

 

[DazedAndConfuzed]

Yup. The percentage does not change with depth. That seems to be consistent with what waterpirate is saying.

I would rephrase it as "Nitrox gives you a reduced percentage of nitrogen when compared to air. This is true at any given depth, since the percentages do not change with ambient pressure."

Wow, I must be really bored to care about this... gotta get back to work!

You can technically say the percentage does change, since the partial pressure changes, and partial is equivalent to percentage. It just comes down to partial or percentage compared to what. If it is compared to the mixture in the tank, it does not change regardless of depth, but if compared to breathing at the surface, it does in fact change with depth.