Nitrox cylinder bands

[kelemvor]

Now days the standards are any nitrox 23.5 and 50 psi or above requires the tank to be O2 cleaned. once cleaned it must have no less than OCA or the clean is void. the need for OCA requires the nitrox band on the tank. to insure grade e or less is not introduced into the tank.

Who sets those? Is it a government agency or a scuba certification agency or other? Just curious, it's the firs time I'd heard there was an actual standard.

I thought it was 02 clean for blending, not for banked fills.

Nitrox stickers so you know what's in the tank is total folly. The only sure way to know what is in your tank is to ANALYSE, ANALYSE, ANALYSE... so analyse and mark it with a bit of ducttape on which you write the expected mix, the analysed mix, date and signature. After a dive pull of the tape.

When it comes to fills it's even more impossible than that, since you'd have to know everything that went into the tank between the last cleaning and that moment. I think at some point, fill stations realize they have to live with the risk or give away a free o2 cleaning with every fill. Nobody would buy their nitrox if they required a clean with a fill at cost.

 

[uncfnp]

No stickers on our tanks except the VIP/O2 clean sticker. Never had a problem getting fills.

KWS. I am only familiar with O2 clean required for greater than 40 or any partial pressure fills.

 

[The Chairman]

NitrOx and all things concerning NitrOx have been central to a lot of controversy over the years. People have been kicked out of the DEMA show for promoting NitrOx and the sticker/cleaning controversy has been going on since. Many of these opinions are of the "do it my way, or you're gonna die" variety, "you should have learned this in your NitrOx class" or the ubiquitous "FIGJAM?" types of statements.

This is another of those areas where the locality and the shops in that locality actually play a huge role. They often don't care what they say on the interwebz... they have their protocol and that's how this is going to happen. You'll either comply with their requirements or you go elsewhere.

As for O2 clean tanks. I avoid Partial Pressure blending whenever possible. I've been poisoned twice with CO due to this. I want banked, membrane or mixed on the fly in my tanks. That's just my personal preference.

 

[fjpatrum]

Most of the shops I've talked to around here won't do Nitrox fills without the stupid stickers, no matter what your vis sticker says. (My tanks have all been O2 cleaned because a shop in FL that did PP blending wouldn't fill my non-O2 cleaned tanks.)

If I find a shop that doesn't require the stupid stickers, that will be my go-to shop now that my previous go-to LDS has closed.

 

[Colliam7]

Not sure where KWS' info came from on anything over 23.5 requiring things to be O2 clean, but since most of my diving and nitrox fills are in cave country, there are some "rules" that are blissfully ignored. I have yet to see anything official come out saying that, but I'm not current on PSI-PCI so it may be from them.

Who sets those? Is it a government agency or a scuba certification agency or other? Just curious, it's the firs time I'd heard there was an actual standard.

This topic periodically comes up on SB, with the ‘discussion' usually going down a somewhat predictable path.

KWS is absolutely correct, about the 23.5% standard. And, the ’standard’ is one set by CGA (Compressed Gas Association) and PSI - PCI, and it is not new. Note, it is NOT federal regulation. Although the CFR reflects CGA standards on many items, the OSHA threshold / standard is still 40%. And, this is one of those standards which poses no problem as long as something doesn’t go wrong. However, in the face of an oxygen fire, or similar event - with injuries / property damage / whatever - in a situation where a banked enriched air mixture of, say, 30% was put into a cylinder with appropriate enriched air markings, but which had not been cleaned for oxygen service, I suspect any smart plaintiff’s attorney would be quick to use the presence of CGA and PSI – PCI ‘standards’ to make a case for negligence. But, I suspect even PSI - PCI is not unrealistic about the actual implementation of the ‘standard’ in the SCUBA world (and I have discussed this with Mark on more than a few occasions). It is simply not practical to require that any cylinder which may be filled with a gas containing 23.5% - 40% oxygen to be cleaned for oxygen service. First of all, the workload for shops to attempt to provide oxygen cleaning (properly performed) for all the cylinders currently being used for Enriched Air would easily overwhelm the current availability of resources (staff, facilities, AND expertise) to do it. Secondarily, the added expense to the user / customer would be substantial. So, even though it is a CGA standard, and a PSI - PCI standard, and is mentioned in every PSI - PCI Visual Cylinder Inspection course, in every PSI – PCI Inspector Update course, and every PSI – PCI Oxygen Service Technician course (to mention just a few), it is simply not common practice.

 

[Peter69_56]

Correct me if I am wrong, If a cylinder is cleaned for Nitrox, or cleaned for Oxygen service, the method is the same. The cost is the same, thus if one is getting a cylinder cleaned, they should ask for oxygen service. That just means the sticker will reflect Oxygen service. We all know however that this is only true until the first unclean air fill. However my point being you either clean or not, there isnt anything in between?

 

[fjpatrum]

I know I get charged extra for O2 cleaning on my tanks. It may be a total scam, I don't know and I don't really care that much. I don't use my shop for much more than fills and Viz/hydro so it's not an exorbitant cost for my 5 tanks.

 

[Peter69_56]

I clean my own and valves. I did notice that the TDI sticker shows Nitrox service and oxygen service. That started me thinking, there is no difference. I am sure in the course there was no discussion on cleaning for one or the other. Just oxygen cleaning, although nitrox/oxygen is discussed and why 0-40% is different from 41-100%

 

[Peter69_56]

From a LDS (Scuba Doctor)
https://www.scubadoctor.com.au/nitrox-o2-clean-cylinders.htm

 

[Colliam7]

Correct me if I am wrong, If a cylinder is cleaned for Nitrox, or cleaned for Oxygen service, the method is the same. The cost is the same, thus if one is getting a cylinder cleaned, they should ask for oxygen service. That just means the sticker will reflect Oxygen service. We all know however that this is only true until the first unclean air fill. However my point being you either clean or not, there isnt anything in between?

A good question. The simple answer is, 'Not at all, for either cost or the method.' Usually, when a cylinder is set up simply for Enriched Air use up to 40%, the only thing that happens is an Enriched Air band/wrap is put on the cylinder, and the VIP sticker looks a bit different - no cleaning of the cylinder or valve is performed. But, that is because the majority of enriched air dispensed in the US is blended before being put into the cylinder, either in banks, or using a 'stick' (membrane) blending approach. For mixtures above 40%, or if partial pressure blending is to be used for the mixture (e.g. 100% O2 is introduced into the cylinder to begin with) then the cylinder (AND valve) should be cleaned for oxygen service (and your comment would be accurate). Cleaning for oxygen service is a laborious process, for which the customer is charged an extra fee (up to $60 depending on the shop that does it). The article you referenced is a good summary of the 23.5% vs 40% issue.

I am not aware of a process of 'cleaning for Nitrox'. A cylinder is either cleaned for oxygen service, or not.