O2 Clean Steel Tanks

[uncfnp]

I have a question along these same lines.... Why is it that after you have a tank O2 cleaned during your hydro that every year after you have to have it re O2 cleaned during your annual VIP? I mean we are talking a $20.00 difference at my shop for the same inspection as an air VIP. Or is there more to the story?

The difference, at least in theory is that a viz is just that, a visual inspection, no cleaning. O2 cleaning should include at least some cleansing of the interior of the tank.

Yearly O2 cleanings? Mine is with each hydro. Unless I know they have been contaminated and I am very careful about that.

 

[boulderjohn]

Recently spoke with a seller about purchasing an LP 50 as a deco bottle and he told me that they come O2 clean.

A scuba tank is made by a company. A valve is made by another company. The two are put together by someone else.

None can guarantee the performance of the other two. A beautifully O2 cleaned tank can have a filthy valve attached. A beautifully O2 clean valve can be put on a beautifully O2 cleaned tank by a greasy-handed employee slathering on thick gobs of silicone grease.

As for the O2 cleaned tank valve combination you had last year, all it takes is one contaminated fill to ruin it.

 

[Shotmaster]

O2 clean is a starting status, once put into service it is subject to contamination. Unless contamination is suspected or it is time to repair, replace or maintenace the device, the working service status remains in place. My LDS only O2 cleans tanks, valves, and regulators before they are put into service for the first time, when things have to come apart like regulator service or if contamination is highly suspected. This saves everyone time and money. You have to start with known good, which is where things start. As far as getting a bad fill, I don't see how filling a cylinder with air would be considered contamination unless the compressor was passing oil and it got past the filters, as all scuba air has to meet the minimum standards for grade E air. If this happened you would have to have your tank and valve cleaned for either service. There are some LDS that like to fleece you, but the antidote to this is a better understanding of what is required and when.

 

[WetLens]

[QUOTE="There are some LDS that like to fleece you, but the antidote to this is a better understanding of what is required and when.[/QUOTE]

I believe the point of this discussion is that we'd like to know what is required and when and not have a moving target at each dive shop we visit. I am trying to understand the difference between a tank tagged for premix only and an O2 clean tank for Oxygen. In my mind, the nitrox tank must be O2 clean. Does an oxygen tank have another level of cleanliness? Even PSI's Nitrox sticker has a box for O2 clean, yet they maintain that anything over 23.5% O2 must be O2 clean. Makes no sense.

 

[boulderjohn]

Even PSI's Nitrox sticker has a box for O2 clean, yet they maintain that anything over 23.5% O2 must be O2 clean. Makes no sense.

I don't think you are going to avoid that moving target, and this is an example.

That 23.5% rule is relatively new, and it comes from the regulations of the Compressed Gs Association (CGA). It is not law. It has not only not been uniformly adopted by the scuba industry, it is rarely adopted by the scuba industry.

 

[uncfnp]

I believe the point of this discussion is that we'd like to know what is required and when and not have a moving target at each dive shop we visit. I am trying to understand the difference between a tank tagged for premix only and an O2 clean tank for Oxygen. In my mind, the nitrox tank must be O2 clean. Does an oxygen tank have another level of cleanliness? Even PSI's Nitrox sticker has a box for O2 clean, yet they maintain that anything over 23.5% O2 must be O2 clean. Makes no sense.

Yes an O2 clean bottle is at least theoritically more clean then a Nitrox bottle since it has gone through an additional cleaning process. The difficulty with some fills and tanks not labeled for O2 is with partial pressure blending when pure 100 % oxygen is first introduced to the tank then air added to give the corrent mix. Be it 24 percent or 99. A tank labeled for nitrox and not O2 does not qualify for PPB at any level.

 

[KevinNM]

That 23.5% rule is relatively new, and it comes from the regulations of the Compressed Gs Association (CGA). It is not law. It has not only not been uniformly adopted by the scuba industry, it is rarely adopted by the scuba industry.

Sadly, not true. At least some of the CGA is incorporated by reference by the DOT as enforceable parts of the CFR.

See this little note about how you can access them for free for a few weeks before you have to pay to know whether or not you are not violating the law. After that, well I hope you have a CGA membership.
DOT / CGA Federal Register Review

And for the 23.5% rule for SCUBA, see this DOT letter

PHMSA - Interpretations by Date - Interpretation #11-0175

 

[boulderjohn]

Sadly, not true. At least some of the CGA is incorporated by reference by the DOT as enforceable parts of the CFR.

See this little note about how you can access them for free for a few weeks before you have to pay to know whether or not you are not violating the law. After that, well I hope you have a CGA membership.
DOT / CGA Federal Register Review

And for the 23.5% rule for SCUBA, see this DOT letter

PHMSA - Interpretations by Date - Interpretation #11-0175

Thank you, Kevin. This certainly updates my understanding.

 

[Shotmaster]

You can't be a little bit pregnant, and you can't be a little bit O2 clean. The removal of all hydrocarbons is what O2 clean means (combustibles have been scoured through mechanical and fluid flushing methods). I think the confusion comes with people not understanding the difference between O2 clean and O2 compatible. There are some materials used for seals, diaphragms, and o-rings used in valves and regulators that are not compatible with O2 service, this is due to containing combustible compounds or will deteriorate too quickly in the presence of O2 as an oxidizer.

This bulletin gives a great explanation and hopefully will clear this up. http://www.documentation.emersonprocess.com/groups/public/documents/bulletins/d100071x012.pdf

 

[WetLens]

You can't be a little bit pregnant, and you can't be a little bit O2 clean.

This is exactly my point. Either it is O2 clean or it is not. Combine all the noted reading in the past few posts and it seems clear to me that all Nitrox tanks need to be O2 clean. Can't be half pregnant.

Now to the bigger issue (in my mind anyway). The same FL shops that will not fill my tanks do nothing other than visual inspection before reapplying an O2 clean label. The NC shop that I used previously would not apply an O2 clean label unless they cleaned on inspection. They did not require O2 clean for Nitrox 40% and below. The NC shop I currently use just punched out O2 clean on my Nitrox tanks after VIP - with inspection only (no cleaning).

It would really be nice if everyone would get on the same page.