One Tank for Air and Nitrox

[NAM001]

My answer is YES as long as the air fill is with grade E hyperfiltered air or better and not just E. Like others havementioned. good luck finding a shop that will do it. I just had a nitrox tank filled with air but the shop required a 15 usd charge in stead of an 8 usd charge for air. Another shop i went to required the vis be scraped and then inspected for air use.

Can I use one tank to fill with air on some dives, and Nitrox for other (deeper) dives? Thanks.

 

[packrat12]

You should change your filling provider, it's not that hard. 5% variance? That's ridiculous for recreational nitrox fills, should be <1% or make them redo it.

How do you define O2 cleaning?

Unfortunately, I have seen a number of fills off by a large amount. When I am renting at the boat, I will just accept if it is within a usable range, no I am not happy about it. I have turned down several tanks because the mix was not usable for the planned dive. I can say there have been no dives where I have needed to worry about exceeding 1.4 even with the off mix that I used. My buddy has a higher SAC so NDL is rarely a limiting factor in my Rec dives so the NDL gain is not a big advantage to me. As for the 5% off, yea I made a comment to the shop worker that they were doing a poor job of mixing which they shrugged off. It is not a shop I would recommend or use because of it. But it was still in range to use (70' dive or so) so we dove with it. I also have been on dives where they would name the person who mixed it if it was off by more than .5%. It was a fun competition so see who blended the best.. A difference in quality of the dive shops I guess and another reason to test the mixture repeatedly both at the shop and on the boat.


'quote' O2 cleaned, cleaned to remove hydrocarbons and residue and filled from only 'clean' hyperpure air sources. A normal compressor is my way of saying not hyperpure. It is also incorrect for someone to assume that if a shop has banked nitrox that the Air is hyperpure, it may not be. I personally try to maintain my O2 gear O2 clean (e.g. try not to introduce hydrocarbons/contaminates etc). I do agree with LowVisWiz document that states that no gear is truly O2 clean after some use. As for my doubles which are also O2 cleaned, I do not consider them to be O2 cleaned as they have been filled from multiple sources and because of this, in my opinion, they are contaminated.

 

[DiamondD]

According to your profile, you're not nitrox certified






---------- Post added June 22nd, 2014 at 06:05 AM ----------





---------- Post added June 22nd, 2014 at 06:09 AM ----------



That's the range where EAN is effective so good idea, but as a newer diver you'll probably run low on air before you hit NDL so better to do more dives first before worrying about nitrox

A guy could have taken the Enriched Air course without updating his profile, I did. And I find that diving on Nitrox, especially when doing several dives a day, I feel better at the end of the day. It's not always about extending NDL.

 

[boulderjohn]

I also got the impression the OP thought nitrox was for deepER dives rather than shallowER dives. It is a common misconception that should be cleared up in a nitrox course, but often is not.

The question is actually a little scary...have you had any training with gas mixes richer than 21%. If you think Nitrox is for deeper dives you either have not taken any training or misunderstood what you were taught.

For the average recreational diver, nitrox really is for deepER dives--no misunderstanding involved.

If you are a single tank diver diving shallower than 60 feet, I think it is generally unwise to use nitrox unless you are getting it free or very cheap. The NDLs on air at those depths are so long that there is no point in going with nitrox. Nitrox for such a diver is much more valuable when you go to the deepER recreational depths, which is what the OP clearly meant. As he said in post #14, "My deeper dives are between 60' and 100'." I am not sure what is so complicated about that, and I am not sure why people feel so eager to beat him up about it.

 

[eweingarden]

DiamondD:
You are correct that my profile is not up to date; I am Nitrox Certified. I'm also not sure why my question seems to have created concern by some of a lack of knowledge about Nitrox. Is it not correct that there is less in-gasing with Nitrox as depth increases ? Is it not correct that there is a shorter surface interval when there is less in-gasing? My bottom times are not limited by NDLs, but by my air consumption. I have a fairly reasonable aerobic capacity which means that the metabolically active tissue in my body (muscle) extracts more oxygen in comparison to someone who's level of physical fitness is less than it could be. Thus, I'm heading up due to air consumption and not NDLs. If I'm ascending due to air consumption and not because I'm approaching NDLs, haven't I reduced my risk of DCS with Nitrox? For the time that I'm down, my choice is to decrease my on-gasing with Nitrox, if I have the option.

My question has to do with tank fills. I appreciate all of the info which has come in thus far.

 

[Steve_C]

I get my tanks refilled as soon as I can after a dive. Given it is NC, dives are often canceled due to weather, my schedule shifts around. I often do not know if my next dive will be at 40 ft or 70ft or 100ft. Simple solution is that I always fill with Nitrox 30%. That is a mix that works on my deepest dives (like to be 1.3 or less).

 

[lv2dive]

I agree about the "deeper" and not understanding why people have an issue with it. 60-110 feet is really a sweet spot for nitrox re the ndl vs. depth compromise of nitrox.

Personally I do see value less than 60 feet but that is related to standard gasses as well as subjective "how I feel" experiences born from years of diving air before switching to nitrox (*enriched* air) the past few years.

For the average recreational diver, nitrox really is for deepER dives--no misunderstanding involved.

If you are a single tank diver diving shallower than 60 feet, I think it is generally unwise to use nitrox unless you are getting it free or very cheap. The NDLs on air at those depths are so long that there is no point in going with nitrox. Nitrox for such a diver is much more valuable when you go to the deepER recreational depths, which is what the OP clearly meant. As he said in post #14, "My deeper dives are between 60' and 100'." I am not sure what is so complicated about that, and I am not sure why people feel so eager to beat him up about it.

 

[beaverdivers]

My answer is YES as long as the air fill is with grade E hyperfiltered air or better and not just E. Like others havementioned. good luck finding a shop that will do it. I just had a nitrox tank filled with air but the shop required a 15 usd charge in stead of an 8 usd charge for air. Another shop i went to required the vis be scraped and then inspected for air use.

We only pump grade E hyper filtered air. We do partial pressure blending. Air is a 21% nitrox mix. All of our tanks have nitrox stickers. ( We do start with Colorado Rocky Mountain pure air )

I have never understood why dive resorts have hundreds of " air " tanks and hundreds of nitrox tanks.
I do believe every tank should be analyzed before it is used.

BTW, we do sell tanks!

 

[eelnoraa]

... Any shop that blends nitrox will be using clean air, so getting an air fill from the same place is no problem. ....

This may not be true. One of my LDS use a filter system to produce recreation nitrox. Their air is NOT O2-cleaned. In this case, any tank can be used for both EAN and air, but a O2-cleaned tank will have O2 clean status void.

---------- Post added June 22nd, 2014 at 10:16 AM ----------

...
I have never understood why dive resorts have hundreds of " air " tanks and hundreds of nitrox tanks.
I do believe every tank should be analyzed before it is used.

I guess same reason as why tech diver permanently mark their tank, less chance of grabbing a wrong tank. I agree every tank should be analye, but thinking back when I was just OW certified, I didn't analyze tanks back then

 

[NAM001]

Thanks,

To day there is no reason why shops do not pump only hyper E The extra pipng and hardware to provide most propably costs more. than the cost of the additional filtering.
There is an old busines saying that 10% of your reasources fix 905 of your problems and 90% to fix the other 10%. In the case of air thta just does not hold true. the final filter to hyperfilter the already e air can last forever compared to the filters to make air grade E.

We only pump grade E hyper filtered air. We do partial pressure blending. Air is a 21% nitrox mix. All of our tanks have nitrox stickers. ( We do start with Colorado Rocky Mountain pure air )

I have never understood why dive resorts have hundreds of " air " tanks and hundreds of nitrox tanks.
I do believe every tank should be analyzed before it is used.

BTW, we do sell tanks!

---------- Post added June 22nd, 2014 at 02:16 PM ----------

Please clarify for me. I know of no such thing as O2 cleaned air. Either the air is O2 compatable (hyperfiltered E) or not. If you blended a mix of 50% deco and used hyp E what is the difference when you provide air with the same hype E in it. If all you pump is hyper E why would you remove the O2 clean sticker from the tank. I understand those shops that do not have hyp E doing this but not the shop supply you reference.

This may not be true. One of my LDS use a filter system to produce recreation nitrox. Their air is NOT O2-cleaned. In this case, any tank can be used for both EAN and air, but a O2-cleaned tank will have O2 clean status void.