Converting from Nitrox to Std Air

[Jonathan]

reminds me of my instructors favourite trivia quiz question on club nights:

What is the most common nitrox mix available?

Amazing how many people that catches out......

Jonathan

 

[Warhammer]

Aardal, when getting/asking for the fill you or whoever that's obtaining the fill needs to make certain that the shop you are getting it from is actually giving you 02 compatible air (aka EAN21/whatever). While all shops that provide nitrox have this capability, I doubt seriously if they all do it that way. The air needs to be filtered through the same filteration system as they do with their nitrox fills, or else it won't be 02 compatable. And those filters aren't cheap, so some may not use them unless necessary. Ask and see. If you fill those tanks with anything other than 02 compatable air, then they are no longer nitrox cleaned. In theory, shops should refuse to fill them with anything else, since they have the nitrox stickers on them. But in the real world, some probably would fill them otherwise. So just ask.

I don't think him getting 02 compatable air will be that big of a deal to any competent shop personnel. But if it is, then the $30 or so per tank, to have them recleaned if he ever needs them for nitrox, isn't hardly worth the trouble.

 

[sharpenu]

The minimum air quality for Nitrox fills is "Modified E" Class. In Florida, all fill stations are required to test their air quarterly using an independant testing lab. They are required to post the results of this test in view of the test station. Ask to see this form at your LDS. I have only found 1 shop (at least here in Florida) that does not have air that is at least "Modified E". Just make sure that the air is "Nitrox Compatible" by being at least "Modified E" or higher and you will keep the Nitrox rating of your cylinders. I routinely dive air for any dive of 50 feet or less and use my nitrox ready cylinders to do it. The only shops who offer nitrox and may not have nitrox compatible air are shops which fill using denitrogenated air instead of the mixing (or blending) method.

 

[daisho]

It's nice that my LDS has what they call "Hyper Clean Air" basicaly 2 or 3 filters so I can fill my Nitrox tanks with AIR.

The reason you don't want to fill a Nitrox tank with air off of a standard compressor in most DS is that if they are not filtered properly you may get small particles or hydrocarbons (so I'm told) that make no difference to us but could combust when you PPB and nitrox fill since the elevated O2 content is more combustive.

As for cleaning. No need until 40%. I know a few people that run 90%+ on there deco stuff and never cleaned. Not sure if I'm that brave though

 

[Tavi]

One of the local shops will do 21% Nitrox fills in Nitrox labeled tanks. But, you have to test it, label it, and log it.

I have been told of another shop that will not put air in Nitrox labeled tanks, Unless you pull the stickers off.

Tavi

 

[sharpenu]

Daisho,
Yes, non clean is usually good for less than 40%, but in the blending method of filling nitrox tanks, 100% O2 is placed in the tank and air is added to bring the mix to the desired percentage. That is why you should O2 clean. That debate has already been done here. My position is known, and if you want to not clean and your shop is OK with that, fine. As for me, I will take the safer route. It is worth the extra $25. It never ceases to amaze me that people here can be so paranoid that they won't trust a dive computer, yet blow off O2 cleaning. Off my soapbox...
Tavi- calling it 21% Nitrox is a scam to charge you for a nitrox fill when you are only getting air. The reason they charge extra for Nitrox is that the O2 that is added costs money. If they won't put air in nitrox tanks, maybe you should be sure of the air quality they are giving you. Non- O2 compatible air is "Grade E", O2 compatible air is "Modified E", the difference being mostly the amount of oil in the gas. You need to ask yourself if you want to breathe the lower quality stuff. Or, is your LDS simply milking you for extra $ by calling it EANx21?

 

[The Chairman]

Their compressor is pretty skank, and I wouldn't want to put their air in a non-oxy cleaned tank either. I had a friend who had his fill done there (they are open to 9:00 and it was an "emergency") and they told him they would have to pull off his NitrOx stickers and he agreed. The only stickers they pulled off were the round decorative stickers... they left the green & yellow bands and the Oxy Clean POI stickers. Too funny, but he was pretty pissed as he had extras of all the others.

 

[Tavi]

Originally posted by sharpenu

Tavi- calling it 21% Nitrox is a scam to charge you for a nitrox fill when you are only getting air. The reason they charge extra for Nitrox is that the O2 that is added costs money. If they won't put air in nitrox tanks, maybe you should be sure of the air quality they are giving you. Non- O2 compatible air is "Grade E", O2 compatible air is "Modified E", the difference being mostly the amount of oil in the gas. You need to ask yourself if you want to breathe the lower quality stuff. Or, is your LDS simply milking you for extra $ by calling it EANx21?

My favorite LDS will do 21% Nitrox fills in Nitrox labeled tanks. They have to be tested and logged because they are Nitrox Tanks (shop policy). I didn't say they charged for a nitrox fill. At 21% I would pay for an air fill. I guess they use what you are calling Modified E.
I just had this disscusion with the owner last week because I want to dedicate my new tanks nitrox (when I get them). But there will be times when I only need air fills.

The other shop that I mentioned, I don't use.

 

[Lost Yooper]

The shop up here doesn't charge for using the filters either. Sometimes you run into really clueless or greedy people at dive shops.

As for the other stuff -- there's nuttin' to worry about.

Mike