O2 Cleaning for Nitrox

[loosenit2]

I am moving this summer and researching some of the local dive sites and operations. Came across this on a local scuba park website:

NOTE: ALL EANx cylinders must be labeled O2 cleaned CGA G 4.1
NOTE: Revised Edition: CGA G-4.1, Cleaning of Equipment for Oxygen Service
January 4, 2019 Cleaning of Equipment for Oxygen Service, an
internationally harmonized publication. This publication
describes the cleaning methods and requirements for
equipment used in the production, storage, distribution,
and use of liquid and gaseous oxygen to reduce the
risk of fire, explosion, or promotion of combustion.
Cleaning in accordance with this publication is required
for all surfaces in contact with a gas or liquid that has
an oxygen concentration greater than 23.5%


So i researched CGA G 4.1. It is recommendations from the Compressed Gas Association. I can't get the actual regulation without paying a couple of hundred $$, but a summary says: Cleaning in accordance with this publication is required for all surfaces in contact with a gas or liquid that has an oxygen concentration greater than 23.5%

This is different than what I thought was an industry standard, anything under 40% did not require O2 cleaning. I understand that O2 cleaning would be necessary if a fill station used partial pressure blending but this site says they bank 32%.

Anyone run into this before?

 

[ScubaBunga]

Yep. Lots of rules, lots of different specs. I personally agree if it’s banked it should not make a difference... then you get into what if’s and I can see why places want anything over 23% needs O2 clean. I took the O2 cleaning class so like my VIP class I can ensure my tanks are up to spec. So just in general most places want O2 clean for everything, so I’m just going to clean everything. Industry standard depends on which industry you look at. Fun times.

 

[boulderjohn]

CGA rules conflict with normal scuba shop practices.

When you get down to it, if you follow the best standard practices to O2 clean your tank, it will not be O2 clean, because a standard scuba valve cannot meet O2 clean standards, no matter what you do to it. Different shops deal with this conflict in different ways.

 

[Scared Silly]

CGA rules conflict with normal scuba shop practices.

Here let me fix that for you:

Many scuba shop practices do not follow the scuba industry standard which is to follow CGA guidelines. Which incidentally are incorporated into the CFRs by reference thus are considered legally binding.

When you get down to it, if you follow the best standard practices to O2 clean your tank, it will not be O2 clean, because a standard scuba valve cannot meet O2 clean standards, no matter what you do to it. Different shops deal with this conflict in different ways.

A scuba valve can meet O2 clean standards what scuba valves can not meet is the design criteria for delivering O2, slow opening (needle valve), not plated (brass), no sharp bends (severe impact angles). There are exceptions.


For the OP here is an older version of the CGA 4.1: https://law.resource.org/pub/us/cfr/ibr/003/cga.g-4.1.1985.pdf

As for the issue, scuba equipment from the regulator downstream can be used with NITROX mixtures of up to 40% O2 with no additional cleaning measures. Upstream, is the cylinder and valve which fall under a different set of standards which state above 23.5% O2 the cylinder and valve must be compatible and cleaned for oxygen use.

 

[tursiops]

CGA guidelines. Which incidentally are incorporated into the CFRs by reference thus are considered legally binding.

It has always seemed odd that you have to pay a private organization to be able to read rules that are legally binding on you.

 

[CuriousRambler]

It has always seemed odd that you have to pay a private organization to be able to read rules that are legally binding on you.

Understatement of the century. I can't believe it's legal to have to pay to read these things. My girlfriend and I rant about this issue constantly; she spent most of her life in public safety, left as a response crew manager (intentionally vague/inaccurate terminology for privacy) to move into the private sector where she's in charge of emergency response and safety for a large chemical plant. She can't even get access to half the binding "policies" she has to answer to, because it sums up to thousand of dollars nobody even realized they should've spent years ago, and "it's just not in the budget right now." Coincidentally, they just got hammered in a government audit for missing a number of points covered in these documents they don't have access to.

I frequently hit the same wall at work, but have a little better luck getting them to buy copies once I justify it.

It just seems criminal to me, to develop regulations that aren't publicly available. Sort of feels like extortion: "Follow these rules, but you have to pay me to see these rules, or we'll fine you if you break them."

 

[bletso]

Yah, we have about a half dozen CGA pamphlets "incorporated by reference" . If you don't have them the DOT can and will fine you big dollars. We have been audited a couple times and depending on the agent it can be a real hassle. It can be a catch 22 as you have to have the edition cited in the CFR and they are updated every so often but the CFR reference doesn't keep up. In other words, you can have a more recent copy than cited and be in violation. Oh, BTW, the one referenced is out of print!!! Again, it depends on if the agent wants to be a horse's backside.

 

[NAM001]

I am moving this summer and researching some of the local dive sites and operations. Came across this on a local scuba park website:

NOTE: ALL EANx cylinders must be labeled O2 cleaned CGA G 4.1
NOTE: Revised Edition: CGA G-4.1, Cleaning of Equipment for Oxygen Service
January 4, 2019 Cleaning of Equipment for Oxygen Service, an
internationally harmonized publication. This publication
describes the cleaning methods and requirements for
equipment used in the production, storage, distribution,
and use of liquid and gaseous oxygen to reduce the
risk of fire, explosion, or promotion of combustion.
Cleaning in accordance with this publication is required
for all surfaces in contact with a gas or liquid that has
an oxygen concentration greater than 23.5%


So i researched CGA G 4.1. It is recommendations from the Compressed Gas Association. I can't get the actual regulation without paying a couple of hundred $$, but a summary says: Cleaning in accordance with this publication is required for all surfaces in contact with a gas or liquid that has an oxygen concentration greater than 23.5%

This is different than what I thought was an industry standard, anything under 40% did not require O2 cleaning. I understand that O2 cleaning would be necessary if a fill station used partial pressure blending but this site says they bank 32%.

Anyone run into this before?

the 40% thing officially died long ago. the death happened when the feds no longer wrote legislation regarding such things because teh policies change faster than new laws can be updated. So they said anything in the federal regulations is considered law . nofw no one wanted the finger pointed at them and thus 23.5 was borbe. It used to be 21 untill they finally realized gas station tire machines had higher contents. adn then thre were a couple of places the had really high O2 levels in the country of perhaps 22%. You may have to look for I think the standard was 23.5 above 50psi or something like that . I see no PSI reflected in this example posted. Now untill this verbage is officially entered in the CFR's it is meaningless and only a recommendation. I would have to look at the working for the CFR but I suspect that teh CFR says do in accordance with CGA G-4.1. which can be changed daily.

 

[yle]

Interesting. The shop I get nitrox from uses a membrane system. They'll fill any tank with up to 36%. I usually have my normal (i.e. not O2 cleaned) aluminum 80's filled with 32%.

Apparently this shop (and they're pretty busy...) is under the impression that a cylinder and valve need only be O2 cleaned if they are to come in contact with gas > 40% O2.

 

[Couv]

I am moving this summer and researching some of the local dive sites and operations. Came across this on a local scuba park website:

My question for the OP. Is that note meant for diving in the park or at the fill station should one want a nitrox fill?