NITROX marked tanks MUST be filled to 24% or greater?

[Rred]

The shop had a very good reason for not wanting to fill that tank. They could put your buddy in the position of "Well, you've either got to rent a tank from us, or you can pay $50 to have your tank O2 cleaned and nitrox labelled before we'll fill it." Either way the shop makes more money.

Safety is never a concern, when there's a potential profit to be made. Especially when you might have a fresh touristy rube to take it from.

Check out the times and profiles that most KL shops use when diving the Vandenburg, typically using an upper deck depth (not bottom depth) and a brief hour's surface interval, so they can run the boat out a second time every day. Now run the same dive and surface interval by any of the printed tables, or any computer with a "safety factor" added in. Funny thing...that surface interval doesn't spell "safety".

 

[fmerkel]

I did take the VIP course during our local H2O show a few weeks back. It was quite good and I now get a much better grasp of the issues at hand, plus I can now VIP my stable of tanks once I get the tools.

This article in the DGX files explains it at better length and detail than I can. The subject is Thermo-valves but the issue of 23.5% and higher is covered.

About "40% MAX OXYGEN" Disclaimers

 

[boulderjohn]

This article in the DGX files explains it at better length and detail than I can. The subject is Thermo-valves but the issue of 23.5% and higher is covered.

About "40% MAX OXYGEN" Disclaimers

That is a good article and well worth reading. I am sure the information in it will be new to many and perhaps most readers, for it is very different from what has been thought in the past. I recently had to recertify as a tank inspector, and the course information had a section with the same information, and it was new to me. What this essentially says is that no scuba valve made by anyone can ever be considered oxygen safe, no matter what you do to it.

The problem is in the design of the valve itself. The flow of the gas through the valve takes too many sharp turns, and there is nothing you can do about it.

The lesson for me is that when I fill the tank and when I use the tank during the dive, everything will be done s l o w l y.

 

[fmerkel]

Now I wish I had a real O2 tank valve to take apart and see what the difference is. Can't imagine it's a whole lot different. It's just some kind of 'stopper' blocking the valve outlet, with some kind of screw mechanism, with some seals to prevent leakage.

The only problem I can see with sharp turns is flow dynamics and the increased possibility of collecting combustible debris when using unclean fill systems.

 

[The Chairman]

Arguing with this LDS will probably be as productive as debating politics...

Ain't it the truth. Ain't it the truth.

However, I require all of my students to measure any tank that is marked NitrOx. Doesn't matter if the shop says it's only filled with air. They have to measure it if so marked.

 

[Wookie]

Now I wish I had a real O2 tank valve to take apart and see what the difference is. Can't imagine it's a whole lot different. It's just some kind of 'stopper' blocking the valve outlet, with some kind of screw mechanism, with some seals to prevent leakage.

The only problem I can see with sharp turns is flow dynamics and the increased possibility of collecting combustible debris when using unclean fill systems.

The difference is in the materials used. An O2 bottle valve is brass on brass, globe valve design. A scuba valve is teflon on brass stop valve design. Hang on, I'll post a picture of a O2 valve.

Edit - Cramer Decker's website must be down, I can't get to the drawing no matter what I do. If you are still interested, go to Cramer Decker and look at the .pdf of a O2 cylinder valve. All brass except a teflon washer behind the stem, where there is no flow.

 

[Rred]

OK, please tell me that anyone else here remembers that on Thanksgiving the radio stations always played "The Alice's Restaurant Massacree" and that we all still remember Alice?

Please remember to prominently label your tanks "ENNEAGAS MIX ONLY" "SEE OWNER'S INSTRUCTIONS"

ENNEA is the greek for "nine", and plain air containers nominally NINE GASSES including nearly 1% of ARGON.

So if the shop really wants to get a knot in their knickers, tell them you want 0.9% ARGON in the mix, and you're damn well going to test for it. You want ALL NINE GASSES in that tank, in the exact percents that you've called for.

Nitrox. Cheap kludge, there's seven gasses missing from that!

 

[boulderjohn]

OK, please tell me that anyone else here remembers that on Thanksgiving the radio stations always played "The Alice's Restaurant Massacree" and that we all still remember Alice?

Our local radio station still plays it.

Nitrox. Cheap kludge, there's seven gasses missing from that!

I'm lost here. What's missing?

 

[Rred]

Well in theory..."Nitrox" would be just nitrogen and oxygen. As opposed to "EAN" which is enhanced AIR and nitrogen. (There were major trademark fights over the two names when that all started.)
So, nine gasses in air. That's right, I want to dive with a NINE GAS MIXTURE and there are acceptable limits and dangers to all of them. From the Wiki folks:

Gas Volume(A)
Name - Symbol - Formula in ppmv(B) - Formula in %
Nitrogen N2 780,840 78.084
Oxygen O2 209,460 20.946
Argon Ar 9,340 0.9340
Carbon dioxide CO2 400 0.04[7]
Neon Ne 18.18 0.001818
Helium He 5.24 0.000524
Methane CH4 1.79 0.000179

What, you never realized a "basic" diver was trained to dive with helium, neon, and argon, all in the standard mix?! Hey, I want those gasses in every bottle I get filled!

 

[Peter69_56]

I use PCTFE or PEEK seats over nylon