44 replies to this topic

[6Gill]

Grey,
You type faster than me

The AAUS defines Nitrox this way: Nitrox is defined for these guidelines as breathing mixtures composed predominately of nitrogen and oxygen, most commonly produced by the addition of oxygen or the removal of nitrogen from air.

RXScuba.com states: Looking at the above definitions we see that nitrox is a combination of Oxygen and Nitrogen -- to be specific, any combination of Oxygen and Nitrogen results in Nitrox.

Most definitions I've seen simply state Nitrox is a gas mixture predominantly composed of nitrogen and oxygen. Those definitions do not state the mix must be higher than 21% (air). Some of the professional divers here state they dive EAN21.


So these do not preclude Nitrox mixes being 21% or less. Your mileage may vary.

To my knowledge there are no Nitrox mixes less than 21% since that would require the removal of oxygen from air. At that point one would use Heliox or Trimix.

There are divers that do mixes < 21% for deep diving. Perhaps not commonly, but it is done by some.

Well there are 3 types of NITROX
1) Hyper >21%
2)Hyoxic <21%
3)Normoxic=21%

The scuba industry accepts the use of the word nitox to usually mean >21%.Mostly because there is no reason(that I can think of) why one would a hypoxic nitox mix for diving.This is not to say that the use of hypoxic doen't exist but it is no longer considered nitox as a 3rd(inert) gas has been added or your using heliox(which in no way resembles nitrox).
THe word nitrox is a poor choice but sounded better oxtrox. I belive that 'enriched air' and EANx are copyrighted but don't know for sure but do better describe the gas from a diver's perspective.

Edited by 6Gill, 18 August 2006 - 11:49 PM.

[jextract]

Not to mention the PITA factor. My nitrox tank is O2 clean, because the primary place I get it filled does partial pressure (SSA in Woodland Hills, the other PP-fill is Malibu Divers courtesy of our own Grant Graves). Other places that fill it are banked, like Hollywoodivers. Now if I take it out on a boat that has it banked, I'm screwed at my primary LDS. If it's easy and not that much of a premium and is appropriate for my diving, I'll do it; if it's a lot more or a PITA I won't.

What are you talking about? Why can't you put banked EAN in your tank and then take it back to your local shop? This makes no sense to me.

Because neither place that fills banked will guarantee that my tank is still O2-clean, post-fill.

[PerroneFord]

What are you talking about? Why can't you put banked EAN in your tank and then take it back to your local shop? This makes no sense to me.

Because neither place that fills banked will guarantee that my tank is still O2-clean, post-fill.

Doesn't this seem odd to you?

There are only 1 of three scenarios available.

1. They are mixing their own Nitrox in which case they are PP blending into their own banks.

2. They are buying premixed EAN in which case someone else is PP blending into tanks and delivering them.

3. They are using DNAX filtering and making Nitrox from air. In which case the air might not be clean enough.


I keep my single 80 as an "air" tank. It might be PP clean, but it might not. I'll check it next month. However, if you have interest, you could take the PSI course and get the gear to oxygen clean and inspect your own gear. This is what I did.

[Mermaid Lady]

Beats diving WITHOUT air!

As a freediver I beg to differ.

[drbill]

Beats diving WITHOUT air!

As a freediver I beg to differ.

Ah, my dear Mermaid... you dive with air, it is just packaged in a different way!

[PerroneFord]

DrBill, it's always about the packaging with you!

[jextract]

What are you talking about? Why can't you put banked EAN in your tank and then take it back to your local shop? This makes no sense to me.

Because neither place that fills banked will guarantee that my tank is still O2-clean, post-fill.

Doesn't this seem odd to you?

There are only 1 of three scenarios available.

1. They are mixing their own Nitrox in which case they are PP blending into their own banks.

2. They are buying premixed EAN in which case someone else is PP blending into tanks and delivering them.

3. They are using DNAX filtering and making Nitrox from air. In which case the air might not be clean enough.


I keep my single 80 as an "air" tank. It might be PP clean, but it might not. I'll check it next month. However, if you have interest, you could take the PSI course and get the gear to oxygen clean and inspect your own gear. This is what I did.

I believe it to be scenario #3.

[PerroneFord]

That's actually quite unusual, because the filtration systems are VERY expensive. It's usually less expensive to go to a blending stik. But hey, if that's what you've got, then that's what you've got.

Sounds like it's time for you to start buying some bottles and get a booster!

[Capn Jack]

To slide back on topic -

The only non-agency specific reference I have handy is the U.S. Navy Diving Manual. (and you can debate the politics of it, too)

It has two interesting chapters in volume two - a chapter on "SCUBA Air Diving Operations" (chapter 7), and one on "Nitrogen-Oxygen Diving Operations" (chapter 10) - where, by the way, NITROX diving is defined as

Nitrogen-oxygen (NITROX) diving is a unique type of diving using nitrogen-oxygen breathing gas mixtures ranging from 75 percent nitrogen/25 percent oxygen to 60 percent nitrogen/40 percent oxygen.

It has an ENTIRE volume (three) dedicated to "Mixed Gas"" where it goes into detail about all of that stuff.

So, when I talk about Air, I'm talking 21% stuff like we normally find in the atmosphere at the surface of our planet. When I say NITROX, I mean the nitrogen-oxygen mix as defined by my alma mater. And when I say Mixed Gas, I'm talking the stuff with helium or some other inert thingy squeezed in to get the oxygen down < 21%.

Feel free to choose your own labels, but this is what I'm going to continue to use.

Edited by Capn Jack, 21 August 2006 - 04:48 PM.

[Walter]

Chapter 15 of the NOAA Diving Manual is Nitrox Diving. In paragraph 2 of the chapter, I find, "'Nitrox' is a generic term that can be used for any gaseous mixture of nitrogen and oxygen, but in the contex of this chaper, the implication is that nitrox is a mixture with more oxygen than that in air."

The glossary defines it: "nitrox [nytrahks] A breathing mixture containing nitrogen and oxygen in various proportions."

[Dive_Girl]

So, would it be fair to say that the term Nitrox when used in general in the industry refers to a Nitrogen/Oxygen mix where the O2 % is greater than 21%?

This is not meaning how do YOU personally use the term, it is what is common-use in the scuba industry.

[Walter]

So, would it be fair to say that the term Nitrox when used in general in the industry refers to a Nitrogen/Oxygen mix where the O2 % is greater than 21%?

This is not meaning how do YOU personally use the term, it is what is common-use in the scuba industry.

Yes, and if you'll look at post 24 of this thread, you'll see I said that 3 days ago.

[Dive_Girl]

So, would it be fair to say that the term Nitrox when used in general in the industry refers to a Nitrogen/Oxygen mix where the O2 % is greater than 21%?

This is not meaning how do YOU personally use the term, it is what is common-use in the scuba industry.

Yes, and if you'll look at post 24 of this thread, you'll see I said that 3 days ago.

so I wasted everyone's time with my post?

Post #24 on this thread on my copmuter is from drbill, however if you meant this post:

You're both right. Nitrox is any mixture of oxygen and nitrogen, although it is only EAN if the oxygen per centage is higher than 21. Typically when referring to nitrox, divers mean EAN.

my post was in reference to the use in the diving industry, but regardless I didn't realize we couldn't make similar posts.

[Walter]

so I wasted everyone's time with my post?

Post #24 on this thread on my copmuter is from drbill, however if you meant this post:

You're both right. Nitrox is any mixture of oxygen and nitrogen, although it is only EAN if the oxygen per centage is higher than 21. Typically when referring to nitrox, divers mean EAN.

I was referring to the diving industry.

I wouldn't say you wasted anyone's time. I was merely pointing out that we are in agreement and have been in agreement.

Mine still shows it as post 24, sorry ours aren't matching up. That is odd, I wonder why the numbers don't jive.

Aug 18 2006, 11:21 PM Post #24

[Dive_Girl]

I wouldn't say you wasted anyone's time. I was merely pointing out that we are in agreement and have been in agreement.

gotcha!