Nitrox vs. Regular Air?

[RickPeck]

Not true.

When you use EAD to dive air tables when using nitrox you aren't given credit for the faster offgassing during ascent and/or stops but you do, in fact, offgas faster...which is why we can use EAN mixes and even pure O2 to accelerate decompression on dives that require staged decompression. For a detailed illustration take a look at any accelerated decompression table or play with some decompression software.

At the risk of being overly blunt, I sure wish the people teaching this stuff would teach the truth about it.

Not sure you are Correct on that Mike. The tissue off gases at a set rate, depending on the type of tissue. Using 100% oxygen does not accelerate the decompression, it prevents re-loading of nitrogen while still at 15 feet (or whatever depth you are at) and that is what reduces decompression time. How would oxygen cause the tissue to release it's stored gas any faster?

Best Regards

 

[espenskogen]

Not sure you are Correct on that Mike. The tissue off gases at a set rate, depending on the type of tissue. Using 100% oxygen does not accelerate the decompression, it prevents re-loading of nitrogen while still at 15 feet (or whatever depth you are at) and that is what reduces decompression time. How would oxygen cause the tissue to release it's stored gas any faster?

Best Regards

Oxygen would increase the gradient which would make you offgass faster. It's referred to as the Oxygen Window

Oxygen window in technical diving - Wikipedia, the free encyclopedia

You learn more details about these aspects of gasslaws in the advanced nitrox and the trimix courses.

 

[espenskogen]

The cost of a dive should never be a factor! Either Do It Right or dont do it at all !! If you go deeper than 100 feet on air you're gonna die !!!

(Heck,who am I kidding ! I was just pointing out that He mixes do not neccesarily have shorter NDL's than air )

And whats with all the names for Trimix? If it contains He,O2 and N2 then its trimix as far as I am concerned. (I only have a trimix card,am I allowed to dive triox or do I have to pay for another course first?? )

Sorry mate, you will need another course and another card - You need the Padi advanced hyperoxic triox card. Don't you know you will need a card for every voodoo gas you want to dive with

E

 

[texdiveguy]

Sorry mate, you will need another course and another card - You need the Padi advanced hyperoxic triox card. Don't you know you will need a card for every voodoo gas you want to dive with

E

Thank God for TDI.

 

[mempilot]

The point is that whilst diving nitrox gives you a longer NDL at a give depth, trimix does quite the opposite, but it eliminates narcosis.

Recreationally speaking, you are wrong. Run a 120 fsw dive for with 15 minutes of bottom time utilizing ean30 and then trimix 30/10. The END for ean30 is 103, and the END for 30/10 is 83. The NDL is the same, but the narcosis level is 20 feet less. What you speak of comes from He ongassing quickly and offgassing quickly. On decompression dives this is important with much longer and deeper dives, but for recreational dives, it isn't. The only big thing to remember when diving recreational trimix vs nitrox is to utilize a very slow ascent rate, which you should be anyways.

So in other words Trimix is a solution to a different problem. To mix it into the NDL discussion and benefits of Nitrox is the absurd bit. Divers who are unfamiliar with mixed gas diving might actually believe that Trimix is the rage for recreational no-stop diving.

Trimix is an extension of nitrox and solves the remaining problem, narcosis. I didn't mix it into the NDL discussion, but merely made an insignificant comment. But thank you for allowing me to show your ignorance on the subject since you would like to expand on the conversation. BTW, Recreational Trimix is a course and is aimed at NDL diving. I'm starting to wonder what level of diving you actual do? You sound like the antagonists of nitrox back in the day.

So in response to your question - Nobody in their right mind would attempt to deco on 18/40 - That'd be crazy. But so would using trimix for recreational depths to extend your no-decompression limit.

I never said anything about extending NDL by using trimix. Where did you get that from? I said trimix has all the benefits of nitrox without the narcosis. You obviously have a hard time understanding a simple sentence like that. Go get some education on the matter.

 

[mempilot]

Yes, that is correct, but why would anyone want to dive 30/30? Just to burn some extra money on gas?

30/30 is usually a nonsense gas. There are some reasons to use it in decompression that go beyond what needs to be discussed in this thread.

I guess if you REALLY hated narcosis, then you could potentially get some benefit out of it..

There are those in the know and there are those that are not.

It's true that the NDL of 30/30 is more than air, but if you compare it to EAN30, it's pretty close. Strictly speaking 30/30 is considered Triox not trimix, but it's close enough I guess.

Any trimix with a FO2>.21 is considered triox. Triox is hyperoxic trimix. What is your point, or should I say, lack of one? What level of certification do you have, and where do you get your misguided information?

 

[mempilot]

Oxygen window in technical diving - Wikipedia, the free encyclopedia

It's all so obvious now where you get your information from.

You learn more details about these aspects of gasslaws in the advanced nitrox and the trimix courses.

Take your own advice there, champ.

 

[abuckfity]

a little bit off-topic here, but: could someone please explain to me why nitrox is not optimal past 100 feet (or another number close, like 110 feet). i see people always mentioning that you shouldn't use it once you go past a certain depth. why not? and what would you want to use instead? trimix?

 

[mempilot]

a little bit off-topic here, but: could someone please explain to me why nitrox is not optimal past 100 feet (or another number close, like 110 feet). i see people always mentioning that you shouldn't use it once you go past a certain depth. why not? and what would you want to use instead? trimix?

The deeper you go, while adhearing to a 'safe' PO2, the FO2 you can use gets close to .21, or air. Therefore, the benefits start to deteriate below this envelope. On the very shallow side, you will have very little N2 loading on a typical recreational dive, and therefore, the benefits of a high FO2 deteriate there as well.

To see what envelope works best for you in reguards to you, you need to take a look at what maximum PO2 you like to dive and what the conditions are. The higher the PO2 you are willing to dive, the deeper the dives you can do and reap the benefits of nitrox. Most training agencies preach 1.2 to 1.4PPO2.

The other factor is the cost of nitrox vs. air fills. If the perceived benefit is low for a deep dive, and the cost of the fill is double, then you do the math. However, nitrox is getting cheaper and closer to the cost of an air fill, at least here in S FL. So even small benefits from nitrox can be worth the little extra cost.

 

[texdiveguy]

I have never liked this silly 'coined' term Triox.