Poll on the use of Nitrox

[tbrown]

I only use Nitrox on vacation. Around here, I really don't feel the extra bottom time is needed. Regular air gives me all the bottom time I need to see our wonders. That and I don't have a relief valve on my drysuit, and my "will to hold" is having enough problems without extending my stay.

[igotoofar]

Now you have me really confused.

This is my understanding. The divers tanks doesn't need to be Oxygen clean if using EAN 40 or below. What I think you are saying is, as long as the divers tank is being filled from a premix this is true, but if the blender is actually mixing the nitrox the divers tank, it would have to be oxygen clean?

Is this what you are saying?

[igotoofar]

GP you posted while I was typeing up my last post.

Why couldn't they put air in first and then top off with O2, which would then get you to the desired mix.

[LKunze]

Yeah, you can get plenty of bottom time on air for local dives but I will say that using nitrox makes me feel less fatiqued at the end of a day of diving. In a perfect world I'd use Nitrox all the time but it's not convenient for me to make a longer commute for nitrox fills and it's also less convenient on the wallet.

[jasondbaker]

Bottom time isn't the only factor when choosing nitrox for local diving. I think depth, water temp, and physical exertion are bigger factors. I like to use nitrox on the first shore dive of the day if the dive is between 70-130ft.

[LKunze]

Because not only does the tank need to be O2 cleaned but the valve does as well. It makes no difference whether you put 100% O2 in first or last the tank and valve still have to be O2 cleaned if PP blending from O2 higher than 40%. I'd recommend taking the Nitrox class for more details.

[tbrown]

Igotoofar, you would still have to have the tanks O2 cleaned. The problem is O2 is very flameable, and some lubricants and even orings can really light up when exposed to 100% O2. Thats why the tanks must be cleaned. Probably why most gear is rated to 40%. Any higher and voila, a flame thrower/bunker buster. I beleive they put the O2 in first to make it easier to make the desired mix. After all it's the amount of O2 that determines the mix, and you can adjust easier by adding air than taking out the O2. But then again I don't PP my own mix. I have enough problems with flameables in my garage.

[igotoofar]

I have already signed up for the nitrox class. (not the advanced class) I have read and re-read the book cover to cover. It doesn't mention details about filling divers tanks with regards to needing an oxygen clean tank if using pure oxygen to fill, Hence my questions.

[tcjtn0]

Quote from gp:
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For me I'd say no because otherwise I wouldn't be able to use regular air in them
anymore, (well I could but they wouldn't be O2 clean anymore ) and unfortunately I
just don't have the cash to shell out on extra tanks to dedicate to nitrox fills only. If
premix were not available then I'd unfortunately probably not use nitrox at all.
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That says it all for me too. Cash for nitrox dedicated cyls is not in my budget at this time.
It would be nice though...
(Sigh...)

Jean

[JoelW]

You don't have to have dedicated O2 cleaned tanks for nitrox that can never be used for air ever again. Find a place that banks pre-mixed. All of my tanks are set up for pre-mixed Nitrox to 40%. Most of the time they have air in them.

The interesting thing that I find with the whole O2 cleaned arguement is what gets topped onto the O2, compressed air from the compressor. So, if you have O2 cleaned tanks can you only get them filled at places that have hyperfiltered air. For that matter, do people ask the condition of the air that is getting topped onto the O2. The final question is if the air that gets topped onto the O2 is clean enough not to foul the tank and valve does that mean that the tank can be filled with just air. So you are now back to an O2 cleaned tank with air in it. A lot comes down to where you get your fills at.

JoelW