converting air tanks to EAN

[adutto]

I want to do this but I've been hearing a lot of nonsense around it. I have a couple of fairly new tanks I want to use with EAN now, so is there any special recommendation on how to "clean" the tanks?

Any comments are welcome!

Thanks!

 

[gcarter]

I want to do this but I've been hearing a lot of nonsense around it. I have a couple of fairly new tanks I want to use with EAN now, so is there any special recommendation on how to "clean" the tanks?

Any comments are welcome!

Thanks!

A shop than banks a given gas such as EAN32 can fill your air tank without requiring an O2 cleaning - O2 cleaning is required over 40%. If partial pressure blending, O2 clean will be required for safety reasons, and the shop may require it for banked mix as well even though that is a business decision rather than a safety requirement.

 

[Peter_C]

^ That is correct information. It really only needs to be cleaned if partial pressure blending. The majority of the places do bank 32-36%.

There are a lot of shops that "require" an ugly NITROX band be applied to the tanks. The minority understand your gas mixture is up to you, and let you keep your tanks free of ugly labels.

 

[boulderjohn]

. The majority of the places do bank 32-36%.

In some places in the world this is true. In many places, it is not. If I want to use nitrox around here, it will be partial pressure blended.

If your tanks are fairly new, a visual inspection will probably reveal that the tank itself is pretty darn clean already, but it will not hurt to clean it. That is easily done. The more important task is cleaning the valve. You can find directions for doing that in a lot of places if you want to do it yourself. If you don't feel confident doing this yourself, you should be able to get the work done by a local shop, and it should not be really expensive.

When it is done, you will want to get a visual inspection sticker on it indicating that it was O2 clean at the time of the inspection.

 

[Scared Silly]

A shop than banks a given gas such as EAN32 can fill your air tank without requiring an O2 cleaning - O2 cleaning is required over 40%. If partial pressure blending, O2 clean will be required for safety reasons, and the shop may require it for banked mix as well even though that is a business decision rather than a safety requirement.

Perhaps true for Canada but not in the USA. In the USA any cylinder filled with greater than 23.5% O2 must be O2 clean per CGA G4.1 as incorporated in CFR 49 171.7.

Additional info: http://www.luxfercylinders.com/frequently-asked-questions

Why does Luxfer require cleaning for oxygen concentrations above 23.5%

Few concepts have caused more confusion and controversy in the recreational diving industry than the so-called “40% rule.” While there seems to be general agreement that special cleaning is required when a pressurized oxygen concentration reaches a particular “threshold” percentage, there is disagreement about exactly what that threshold should be and at what pressure it becomes important. Some say 40%; others say 23.5%; still others say anything more than 21% when a gas mixture is pressurized more than 100 psig. It would be helpful to explore the background of this confusion briefly before discussing Luxfer’s position on this vital subject.
The 40% threshold is cited in a single Federal CFR published by the Occupational Safety and Health Administration (OSHA) of the U.S. Department of Labor: 29CFR910.430, which applies to “Commercial Diving Operations” and states in the section titled “Oxygen safety” on page 854: “(1) Equipment used with oxygen or mixtures containing over forty percent (40%) by volume oxygen shall be designed for oxygen service. (2) Components (except umbilicals) exposed to oxygen or mixtures containing over forty percent (40%) by volume oxygen shall be cleaned of flammable materials before use.”
Please note that OSHA also provides a very specific definition about who should—and should not—be considered a “commercial diver” to whom the 40% threshold applies: “Commercial diver means a diver engaged in underwater work for hire excluding sport and recreational diving and the instruction thereof” (46CFR197, page 409; italics added for emphasis).
Even though OSHA clearly excludes sport and recreational divers from the CFR that specifies a 40% threshold, some professionals in the recreational diving industry have nonetheless been citing the OSHA “rule” for many years and maintaining that special cleaning of recreational diving equipment is not necessary with oxygen concentrations of 40% or less. These advocates of the “40% rule” have often stated that the U.S. Navy supports their position, which at one time was true—but no more. In the current applicable military specification (Mil-Std-1330D), the Navy specifies a 25% threshold for oxygen cleaning. Compounding the confusion is the fact that two other OSHA documents, 29CFR1910.146 and 29CFR1910.134, specify an oxygen threshold of 23.5%.
For the sake of clarity, here’s a summary of the oxygen threshold percentages at which various key U.S. agencies and organizations require special cleaning of oxygen-handling equipment and systems:

Organization	Oxygen threshold	Reference
U.S. Navy	>25%	Mil-Std-1330D
U.S. Compressed Gas Association (CGA)	>23.5%	CGA Pamphlet 4.4
National Fire Prevention Association (NFPA)	>21 – 25%	NFPA standards
American Society for Testing & Materials (ASTM)	>25%	G126, G128, G63, G94
National Aeronautical & Space Administration (NASA)	>21%/>100 psig	Various KSC & JSC
Occupational Safety & Health Administration (OSHA)	>23.5%	29CFR1910.146
OSHA	>23.5%	29CFR1910.134
OSHA	>40%	29CFR1910.430

The reasons for Luxfer’s position: Luxfer supports an oxygen-cleaning threshold of 23.5% and does not support the alleged “40% rule.” This means that when a pressurized oxygen concentration used in a Luxfer cylinder exceeds 23.5%, the cylinder must have been cleaned to the same cleanliness standard mandated for a cylinder containing 100% oxygen. Luxfer’s reasons for this position are:
o All key U.S. regulatory and gas industry references except one advocate an oxygen threshold of 21% to 25%.
o Luxfer is a member of the Compressed Gas Association and therefore supports the CGA-specified threshold of 23.5%. Furthermore, Luxfer defers to CGA on all safety matters related to oxygen handling and containment, as do OSHA and DOT.
o As an international manufacturer, Luxfer works with regulatory authorities and industry associations around the world—the overwhelming majority of which support a threshold value from 21% to 25% (for example, this is true in the United Kingdom, Australia, France, Germany and Japan).
o United Nations compressed air packaging guidelines (see UN 1002) indicate that when compressed air contains oxygen as the only oxidizing gas and the oxygen concentration exceeds 23.5%, then the entire gas mixture must be listed as an oxidizing gas.
Some within the recreational diving community contend that the supposed “40% rule” is justified by an excellent scuba safety record and should therefore be maintained—despite the fact that so many agencies and organizations have specified much lower threshold values for oxygen cleaning. Luxfer finds this “history-of-use” argument unconvincing for the following reasons:
o Compared to other industries and organizations that use pressurized oxygen, oxygen usage in the recreational diving industry has not been sufficiently widespread, nor are available oxygen-use statistics sufficiently comprehensive, to declare a successful history of use for the 40% threshold.
o Oxygen-related fires and explosions are inherently low-probability, high-consequence events—which means that they occur very infrequently, but are usually catastrophic when they do. Forensic evidence has shown that undetected, non-propagating fires happen within scuba oxygen systems more frequently than is generally known. It is possible to operate “on the edge” of a fire for years without knowing it—and to be lulled into complacency by seemingly “safe” performance.
o As use of higher oxygen concentrations at higher pressures increases in the recreational diving industry, the risk of serious accidents will also increase.
Under these circumstances, Luxfer believes that requiring thorough oxygen cleanliness at a threshold of 23.5% makes very good sense not only for the sake of individual safety, but also from the business standpoint of prudent risk management.

 

[WheelsUSN]

Perhaps true for Canada but not in the USA. In the USA any cylinder filled with greater than 23.5% O2 must be O2 clean per CGA G4.1 as incorporated in CFR 49 171.7.

This is incorrect. If you read CFR 49 171.7 it incorporates CGA G4.1 only as it applies to CFR 49 178.338-15. 178.338-15 relates to the required cleaning for a cargo tank which is defined in the CFRs as:

Cargo tank means a bulk packaging that:
(1) Is a tank intended primarily for the carriage of liquids, gases, solids, or semi-solids and includes appurtenances, reinforcements, fittings, and closures (for tank, see §§ 178.337-1, 178.338-1, or 178.345-1, as applicable);
(2) Is permanently attached to or forms a part of a motor vehicle, or is not permanently attached to a motor vehicle but that, by reason of its size, construction, or attachment to a motor vehicle, is loaded or unloaded without being removed from the motor vehicle; and
(3) Is not fabricated under a specification for cylinders, intermediate bulk containers, multi-unit tank car tanks, portable tanks, or tank cars.

since a scuba tank is not permanently attached to a motor vehicle and is fabricated under a specification for cylinders it is not covered by the CFR.

 

[antattack]

That's a lot of interesting detail. It's probably important to understand if you are a tech working for the LDS.

Where I dive, very few shops bank Nitrox. That means that if I need a nitrox fill, it will be partial pressure blended.

And that means my tanks need a sticker issued by a tech affiliated with a shop, with the ANDI reg number on it.

And the ONLY way I have found is to get that sticker by having the bottle and valve cleaned at the LDS.

So I conclude, perhaps wrongly, that if you have a bottle that you want to use with Nitrox, it's practical to get the bottle and valve O2 cleaned at the LDS, get the sticker and you are done.

Did I get that wrong?

 

[gcarter]

That's a lot of interesting detail. It's probably important to understand if you are a tech working for the LDS.

Where I dive, very few shops bank Nitrox. That means that if I need a nitrox fill, it will be partial pressure blended.

And that means my tanks need a sticker issued by a tech affiliated with a shop, with the ANDI reg number on it.

And the ONLY way I have found is to get that sticker by having the bottle and valve cleaned at the LDS.

So I conclude, perhaps wrongly, that if you have a bottle that you want to use with Nitrox, it's practical to get the bottle and valve O2 cleaned at the LDS, get the sticker and you are done.

Did I get that wrong?

I modify it a bit - if you want to get your tank filled anywhere you take it, get the O2 clean.

If your LDS will fill with banked without an O2 clean and you are ok with the fact that another LDS may only give you air, don't bother.

Spend the money required to meet your expectations, but do it with your eyes open.

 

[MaxBottomtime]

Fortunately, my LDS uses a small strip of masking tape with the mix written on it. They do sell those silly giant green stickers, but probably feel bad about doing so.

 

[boulderjohn]

That's a lot of interesting detail. It's probably important to understand if you are a tech working for the LDS.

Where I dive, very few shops bank Nitrox. That means that if I need a nitrox fill, it will be partial pressure blended.

And that means my tanks need a sticker issued by a tech affiliated with a shop, with the ANDI reg number on it.

And the ONLY way I have found is to get that sticker by having the bottle and valve cleaned at the LDS.

So I conclude, perhaps wrongly, that if you have a bottle that you want to use with Nitrox, it's practical to get the bottle and valve O2 cleaned at the LDS, get the sticker and you are done.

Did I get that wrong?

Those area your shop regulations. They do not pertain to all other places in the world.

My tanks are O2 cleaned, and I myself, as a certified tank inspector, have slapped an O2 clean sticker with my inspector number on it each year. It does not have an ANDI reg number on it--it has my PSI number on it. It has never been turned down for filling anywhere I have taken it. It sounds like your shop is looking for a little extra cash.