Air fills in O2 cleaned tanks...

[willydiver]

Got a question for the air/NO2 filling experts.

My LDS does not offer Nitrox fills. They refuse to give me plain air fills in tanks with an "O2 cleaned" VIP sticker. They will only fill them with plain air after replacing the O2 cleaned VIP sticker with a regular air fill VIP sticker. This results in my tanks losing their Nitrox approved standing. Their claim is that by filling a Nitrox approved tank with plain air, you are somehow invalidating that tank's Nitrox "cleanliness".

To me, this doesn't make sense. The purpose of O2 cleaning a tank is to remove contaminents that may cause an ignition when partial pressure filling a tank with pure O2. This done once with new tanks and/or once a year with the annual VIP.

When filling Nitrox using the partial pressure method, plain air is filled on top of the pure O2. When filling a tank with partial pressure Nitrox or just a plain air fill, you're still using the same air. How in the world does the tank somehow become "non-Nitrox compatible" just by leaving out the pure O2 during the fill process??? Any shop filling tanks should be filtering their air to the best practically achievable purity anyway. Shouldn't they.... I hope??!!

I use plain air fills in the rivers and only use Nitrox offshore. Nitrox fills here are steep at $15+. So I like to have the ability to cheap-out and get plain air when I can. The LDS started talking about insurance, NOAA recommendations, etc. I appreciate their existence and the service they provide, so I had to bite my tongue and not pursue the argument.

Anybody know the facts on whether or not you can fill a Nitrox approved tank with plain air without invalidating it's Nitrox standing?? The other shop I use has no problem with it but they are 50 miles away.

Thanks,
Will

 

[The Kraken]

Not exactly.

To do partial pressure blending the "air" has to be O2 compatible. It's a more highly filtered air.

Tanks that have been O2 cleaned can be filled with "E" grade, or O2 compatible air, but not air from a standard filtered compressor.

the K

 

[willydiver]

Thanks for the reply Kraken.

So my "air fills only" LDS compressor must not filter their air to "E/O2 compatible" grade. Not being a Nitrox shop, I guess they don't need to. That would explain why the Nitrox shop 50 miles down the road can put plain air fills in my Nitrox approved tanks, but my LDS can't.

Guess I can quit being upset and just be happy I can get my pups filled in town!

Thanks,
Will

 

[wreckchick]

Well, shop's should be providing the cleanest air possible and many of them are. The difference is not actually in the air quality but the tests that are performed to validate this. If a shop isn't doing PP blending then they probably aren't having the air tested to Mod Grade E standards. It isn't that it isn't, but they don't know that. I would do the same thing given their situation.

Rachel

 

[pescador775]

This is a no win area. I have a friend who partial pressure fills with an old Bauer Utilus portable. The compressor uses the standard Bauer PO filter with Bauer triplex cartridge. He has never had a problem and I doubt he ever will. The various rules set down by the Nitrox "agencies" are quite stringent with some being more "holy" than others. Dive shops have "policies", some based on myth, some related to pieces of paper, another kind of policy. Their insurance may have provisions which require that the shop abide by "existing standards" and that would rule out filling an O2 tank with Grade E air. To meet these standards they would probably have to fill to modified Grade E or "hyper air" and that means additional (expensive) filtration.

 

[oly5050user]

Thanks for the reply Kraken.

So my "air fills only" LDS compressor must not filter their air to "E/O2 compatible" grade. Not being a Nitrox shop, I guess they don't need to. That would explain why the Nitrox shop 50 miles down the road can put plain air fills in my Nitrox approved tanks, but my LDS can't.

Guess I can quit being upset and just be happy I can get my pups filled in town!

Thanks,
Will

you want hydro carbon free air...to keep tanks o2 clean..and still use with nitrox using partial pressure filling.additional filters so additional cost..this is what we do here..

 

[SparticleBrane]

For shops that fill air over top of nitrox then there shouldn't be any problem, as the air they are using to do that SHOULD be hyper-filtrated. Then again, that doesn't mean it is....

For the shop I worked at we used entrailment to add pure O2 to air to create 40% premix. Then we could make whatever we wanted from there by topping it off with air to bring the O2 % down a bit. Our air was run through (IIRC) 3-4 filters before it ever touched a tank.

 

[waterbearer]

I'm glad somebody posted this. I was wondering about the same thing. The shop I usually get my nitrox fills from uses continuous flow. They have no problem filling my tanks with either nitrox or just air. I have gotten nitrox fills from another shop, they have no problem (I did notice the drain the tanks before filling). The third shop that only does air fills has no problem. Should I be concerned that no one has questioned when I only wanted air in the tanks?

 

[Hoosier]

I'm glad somebody posted this. I was wondering about the same thing. The shop I usually get my nitrox fills from uses continuous flow. They have no problem filling my tanks with either nitrox or just air. I have gotten nitrox fills from another shop, they have no problem (I did notice the drain the tanks before filling). The third shop that only does air fills has no problem. Should I be concerned that no one has questioned when I only wanted air in the tanks?

As I understand, the continuous flow is a different animal. You can fill any kinds of tanks with the continuous flow without having O2 clean because the air has been pre-mixed. But, it doesn’t mean that the air from the continuous flow is hyper-filtered. So, you may or may not contaminate the tanks. O2 clean is only required for PP mixing.

 

[waterbearer]

As I understand, the continuous flow is a different animal. You can fill any kinds of tanks with the continuous flow without having O2 clean because the air has been pre-mixed. But, it doesn’t mean that the air from the continuous flow is hyper-filtered. So, you may or may not contaminate the tanks. O2 clean is only required for PP mixing.

The tanks have been O2 cleaned. Does anyone have a problem putting just AIR into nitrox tanks or it it okay to do so?