Do Nitrox dedicated cylinders need to be O2 cleaned every year?

[RSdiver]

I bought 19 cu ft a pony tank 3 years ago and it has always been used for Nitrox, and always Visual plus+ VIP'ed for Nitrox.
I just had this year's annual performed at a different store (because I moved), Pacific Wilderness, in San Pedro, CA. When I dropped it off the store attendant asked me if I wanted it VIP'ed for 22-40% or VIP'edfor all blends (40%+). I never get fills above EAN36, so 22-40% seemed fine. When I returned to pick it up I chatted with him some more and he told me it had been filled with air because they fill by blending and he couldn't blend because it wasn't oxygen cleaned.
Thanks for telling me afterwards...

This has never been a problem before because I've always had the VIP done at Any Water Sports in San Jose where they have a bank of pre-mixed Nitrox.
Is it normal for Nitrox tanks to be required to be O2 cleaned every year?



Following is the post from "computers" section of this board

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I have only heard of one item (other than price) that concerns me about this computer. A LDS (Pacific Wilderness) dude, said that digital compasses suck because they react too slow, compared to a real compass. Anybody want to comment on that?
(PS- I am never going to buy anything out of that stinking store again, the guy that I talked to was a jackalope- mister attitude- I am so *****in' and you are a sand flea, type of guy.).

Yeah, I know I've had either great or bad out of the San Pedro Pac Wliderness store, so I wouldn't buy a computer like this from them. If there were upgrades, returns, or any difficulty, I just don't know what kind of service to expect.

For example, 2 weeks ago I took my Nitrox tank in for it's annual VIP and the guy said it would be done in half an hour. I came back and he said that because I didn't have it Oxygen cleaned this time that it was VIP'ed for only up to 40% O2. I commented that I never go above EAN36 anyways so that seemed fine.
After a few more questions I found out that I can never have it filled with Nitrox there because the fill by blending.
Thanks for telling me afterwards...

Do Nitrox tanks need to be O2 cleaned every year?
I'll post this in the tank section also...

 

[Warren_L]

This has never been a problem before because I've always had the VIP done at Any Water Sports in San Jose where they have a bank of pre-mixed Nitrox.
Is it normal for Nitrox tanks to be required to be O2 cleaned every year?

I'm certainly no expert in this area, but I seem to recall that oils and particulate matter can build up over time even though the grade of air used in the cylinder may be to O2 specifications. This might suggest that an O2 clean may be required eventually, but I don't know if every year is the magic number.....

 

[Padipro]

There is no such thing as cleaning a cylinder for 22% to 40% or cleaning a cylinder for mixes above 40%. It's either cleaned or it's not. What the store is talking about is that technically a cylinder doesn't need to be cleaned for pre mix/banked Nitrox mixes 40% or less because oxygen above 40% never touches the tank. If a shop does partial pressure blending then pure, 100%, O2 is added to the tank and then specially filtered air is added on top to get the desired mix. In this case the tank and valve must be cleaned to remove any contaminants. If the shop you previously used banked pre mix they most likely didn't clean the tank as it wasn't necessary and the new shop, using the partial pressure method of blending would need to clean the tank before they could fill it.

 

[jbd]

There is no such thing as cleaning a cylinder for 22% to 40% or cleaning a cylinder for mixes above 40%. It's either cleaned or it's not. What the store is talking about is that technically a cylinder doesn't need to be cleaned for pre mix/banked Nitrox mixes 40% or less because oxygen above 40% never touches the tank. If a shop does partial pressure blending then pure, 100%, O2 is added to the tank and then specially filtered air is added on top to get the desired mix. In this case the tank and valve must be cleaned to remove any contaminants. If the shop you previously used banked pre mix they most likely didn't clean the tank as it wasn't necessary and the new shop, using the partial pressure method of blending would need to clean the tank before they could fill it.

What Padipro has posted should have been explained to you up front by the shop personnel.

 

[padiscubapro]

There is no such thing as cleaning a cylinder for 22% to 40% or cleaning a cylinder for mixes above 40%. It's either cleaned or it's not. What the store is talking about is that technically a cylinder doesn't need to be cleaned for pre mix/banked Nitrox mixes 40% or less because oxygen above 40% never touches the tank. If a shop does partial pressure blending then pure, 100%, O2 is added to the tank and then specially filtered air is added on top to get the desired mix. In this case the tank and valve must be cleaned to remove any contaminants. If the shop you previously used banked pre mix they most likely didn't clean the tank as it wasn't necessary and the new shop, using the partial pressure method of blending would need to clean the tank before they could fill it.

If its an aluminum luxfer or catalina cylinder according to BOTH manufacturers ANY oxygen enriched mixture requires the cylinders be kept oxygen clean.
Any store that fills tanks with enriched air and doesn't maintain it to oxygen standards is risking serious liability issues if anything happens by going against the manufacturer.

see
http://www.luxfercylinders.com/support/faq/aluminumoxygen.shtml
(specifically look at #3 and #4)
http://www.catalinacylinders.com/oxycomp.html

Both manufacturers both Specifically recommend ANDI's oxygen cleaning/handling procedures.

 

[Padipro]

If anything is going to happen it's going to happen while being filled when the 100% O2 is added and that would most likely only affect the shop staff. Once the tank is completely filled and the mix is 40% or below there's little chance of anything happening to the diver using it.

 

[Wally1716]

There is no such thing as cleaning a cylinder for 22% to 40% or cleaning a cylinder for mixes above 40%. It's either cleaned or it's not.

..
This statement, as true and universal as it might be, is contended
by a small techie agency that requires its facilities to "safe-clean"
tanks that use any gas with over 23.5% O2. So their facilities are
bounded to follow that standard.
..
It's like a religion...each one follows what they believe the most.
..

 

[Padipro]

Hay Wally,

I've run into this very issue several times down here. One shop fills the tanks and never even looks at the VIP sticker to see if it's been cleaned and inspected another will question everything, and even call the shop that preformed the inspection and cleaning to verify exactly what was done, before they will touch the tank. I believe some folks still look at gas blending as a "Black Art" that's beyond understanding. I've asked the shop where I had this problem to explane to me the differance between the two cleaning methods and no one could. I was told that some shops that blend Nitrox don't use hydrocarbon free air for mixing because they use a membrain system and that tanks filled by this shop are no longer suitable for PP blending. I'm not going to mention the name of either shop but both are very reputable and the one supposedly using unclean air is a big techie shop offering everything from air to Hypoxic Trimix so I find it hard to immagine that they would do something like like that. I haven't had the chance to varify this with the shop but intend on doing so the first chance I get. Knowladge is power so if you know what you're talking about when confronted with a situation like this they can't BS you but you're right everyone seems to have they're own standards.

 

[domino22]

my shop does it that way too $$$. They also partial blend so that may be why but damm it is $$$.

 

[padiscubapro]

..
This statement, as true and universal as it might be, is contended
by a small techie agency that requires its facilities to "safe-clean"
tanks that use any gas with over 23.5% O2. So their facilities are
bounded to follow that standard.
..
It's like a religion...each one follows what they believe the most.
..

Read the luxfer FAQ, the list all the established standards.. Almost everyone but portions of the dive industry set the limitis slightly above "air".. no where near the mythical 40% rule