Bad memory? O2 Clean required for less than 40% nitrox

[Divin'Papaw]

Many shops follow the rule, some do not. As such, your emphasis on no one is misplaced. Especially as you even note an exception. And no boom does not mean no problem.

There are some cases I have heard about where there have been issues when filling directly with nitrox sans O2 cleaning. However, finding documentation has been hard.

The ‘rules’ as you quote them are antiquated and convoluted. It’s not even crystal clear to whom all they apply. It’s not all that surprising. It happens over time with industry regulations.

The scuba ‘industry norm’ that has developed is to require O2 cleaning for PPB and for Nitrox over 40%. That is clearly working well for the industry as that is what the vast majority of shops follow with few (if any) incidents. Someday the ‘rules’ just may catch up.

 

[shurite7]

Wrong. Cylinders being filled with more than 23.5% O2 are required to be O2 clean. That is what the CGA rules state which are referenced by the US CFRs.

The above myth gets debunked as nauseum.

To help your claim would you provide the exact CFRs from CGA that state anything above 23.5% requires O2 cleaning.

 

[boulderjohn]

Once you have figured out that strictly following CGA rules makes it darn tough to put nitrox in a scuba tank, check out the rules on valves to see how standard scuba valves fare in the rules.

 

[tursiops]

To help your claim would you provide the exact CFRs from CGA that state anything above 23.5% requires O2 cleaning.

https://chem-space.com/public/regulatory/49 CFR (US DOT).pdf
Electronic Code of Federal Regulations (eCFR)

Oxidizing gas means a gas that may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does. Specifically, this means a pure gas or gas mixture with an oxidizing power greater than 23.5% as determined by a method specified in ISO 10156: or 10156-2: (IBR, see §171.7 of this subchapter) (see also §173.115(k)).​

And most especially:
Revised Edition: CGA G-4.1, Cleaning of Equipment for Oxygen Service - Compressed Gas Association

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%, including stationary storage tanks, road tankers, and rail cars; pressure vessels such as heat exchangers and distillation columns; compressors and pumps; and associated piping, valves, and instrumentation.​

 

[WetLens]

Got caught up in the same debate several years ago when a shop in FL refused to fill my tanks. They banked Nitrox, so I really didn't understand the issue. Did some research and found the industry rules cited in previous posts. Long story short - had all of my tanks O2 cleaned, valves serviced, and haven't had an issue since. There was an initial expense, but have not had any upcharges since as my tanks have passed visual inspection without issue. I agree with others that have said there should be one set of standards that the dive industry follows. From a liability standpoint, don't see how it could be other than what the CGA standards states.

 

[shurite7]

https://chem-space.com/public/regulatory/49 CFR (US DOT).pdf
Electronic Code of Federal Regulations (eCFR)

Oxidizing gas means a gas that may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does. Specifically, this means a pure gas or gas mixture with an oxidizing power greater than 23.5% as determined by a method specified in ISO 10156: or 10156-2: (IBR, see §171.7 of this subchapter) (see also §173.115(k)).​

And most especially:
Revised Edition: CGA G-4.1, Cleaning of Equipment for Oxygen Service - Compressed Gas Association

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%, including stationary storage tanks, road tankers, and rail cars; pressure vessels such as heat exchangers and distillation columns; compressors and pumps; and associated piping, valves, and instrumentation.​

It is posts like this that make a claim credible and reliable.

It is interesting that scuba tanks or valves are not mentioned.

Another interesting thing I come across with gas companies is, when I asked what they did to O2 clean their large (k type bottles) and medical cylinders they stated nothing in particular other than looking inside to make sure there was no moisture and the cylinder was clean.

 

[tursiops]

It is interesting that scuba tanks or valves are not mentioned.

If you look at the material, you'll see that scuba is irrelevant. It is not a special category that gets more scrutiny or less.

 

[Scared Silly]

The ‘rules’ as you quote them are antiquated and convoluted. It’s not even crystal clear to whom all they apply. It’s not all that surprising. It happens over time with industry regulations.

It is crystal clear to whom all the rules apply. People just choose to willing ignore it.

The scuba ‘industry norm’ that has developed is to require O2 cleaning for PPB and for Nitrox over 40%. That is clearly working well for the industry as that is what the vast majority of shops follow with few (if any) incidents. Someday the ‘rules’ just may catch up.

If that were they case do you not think that the scuba industry would have already done some work? Because at the end of the day it comes down to liability and fines. It may not take a direct incident for OSHA to investigate, nor would it take much for an insurance company to deny a claim.

 

[Divin'Papaw]

It is crystal clear to whom all the rules apply. People just choose to willing ignore it.



If that were they case do you not think that the scuba industry would have already done some work? Because at the end of the day it comes down to liability and fines. It may not take a direct incident for OSHA to investigate, nor would it take much for an insurance company to deny a claim.

If it is so clear and if the vast majority are out of compliance, where’s the enforcement? Where are the fines? Where are the incidents of O2 fires caused by filling banked 36% into non-cleaned tanks? I’m not aware of any, are you?

 

[Divin'Papaw]

Got caught up in the same debate several years ago when a shop in FL refused to fill my tanks. They banked Nitrox, so I really didn't understand the issue. Did some research and found the industry rules cited in previous posts. Long story short - had all of my tanks O2 cleaned, valves serviced, and haven't had an issue since. There was an initial expense, but have not had any upcharges since as my tanks have passed visual inspection without issue. I agree with others that have said there should be one set of standards that the dive industry follows. From a liability standpoint, don't see how it could be other than what the CGA standards states.

You can’t clean them just once. You need to have them cleaned at every VIP. It gets time consuming and expensive.