nitrox to 23.5%?

[rjgiddings]

I had the same exact question when I saw an AL40 on LeisurePro's web site.

As I type this today - it says says Nitrox Ready uo to 40% and when you click on the details - it then says 23.5%.
" Note: All Luxfer cylinders are nitrox ready up to 23.5%and meet certificated specifications of the US Department of Transportation (DOT) " Sound confusing? Yeah. Me too.

I did a quick chat w/ one of their sales folks - who immediately said - the tank is manufactured to up to 23.5% and if I choose to go w/ any other Nitrox fill percentage- it is all on me to get this tank O2 cleaned first.

I would say - if anybody from LeisurePro is reading this - go fix the website. IF your consumer has to go get the tank cleaned for Nitrox, then DONT sell them as being ready for a 40% blend. I mean, really folks. One or the other.

 

[Lorenzoid]

More accurate would be "SLIGHTROX-ready up to 23.5%."

 

[boulderjohn]

As has been noted, it is all to be compliant with the CGA standard--they have to say that for that reason. The problem is that scuba cylinder use will always be at odds with those standards, which are made with other kinds of cylinders in mind. Nobody else uses nitrox. For them, cylinders will have either air in them or oxygen, so the designation makes sense.

I discovered a similar issue when I bought some valves intended to go on decompression bottles. The literature that came with the valves said that they could never be used for anything above 40%. Never. There is nothing you could do to make them O2 clean. I called the maker (Thermo), and you could almost hear the representative winking when he said that 40% was indeed the limit.

When I renewed my PSI-PCI inspection certification, it was all made clear in language I had never seen in my previous cylinder inspection instruction. It is not possible to make a scuba valve O2 compliant according to current standards because the gas makes too many turns on its way in and out of the valve. This puts an inspector, like me, in a real bind. If we OK a scuba cylinder for oxygen service, we do so knowing that it really can't be done. You can never put anything more than 40% in a scuba cylinder and be within standards.

 

[Chris H]

As others have mentioned, the specification for breathing air is 19.5%-23.5% Oxygen. This has nothing to do with the dive industry.

 

[halocline]

It sounds like luxfer is covering its ass with the 23.5% statement because that's what the CGA currently qualifies as the upper limit for non-O2 cleaned cylinders.

Don't forget that the CGA is a trade organization, not a governmental regulatory organization, and as such has no explicit legal power. If a company were to be sued for negligence, certainly a lawyer would make a case that the "industry standards" are assumed to be in compliance with the trade organization, but that's it.

Scuba training organizations like PADI have been teaching for years that sub-40% O2 is recreational nitrox and requires no special equipment, including scuba tanks. So there is apparently a conflict in "industry standards". Maybe someday there will be a big court case and this will come up.

I personally would not hesitate to fill a new luxfer scuba tank (or any other tank) with nitrox under 40% without O2 cleaning. As long as the tank is not exposed to 100% O2, I just don't see any sort of risk. To my knowledge there has never been an O2 related fire on equipment only exposed to 40% or less O2.

But that's my personal opinion, take it for whatever you want.

 

[TrimixToo]

Don't forget that the CGA is a trade organization, not a governmental regulatory organization, and as such has no explicit legal power. If a company were to be sued for negligence, certainly a lawyer would make a case that the "industry standards" are assumed to be in compliance with the trade organization, but that's it.

49CFR incorporates a number of CGA publications by reference. I'd love to have copies of them all. I find it especially irksome that they are incorporated by reference in federal regulations but not publicly available. Grrrrrr.....

 

[fmerkel]

Unfortunately a large percentage of shops still partial pressure blend. My LDS still does, which is why I ended up creating the thread on 24%. Hassle for me AND them.

 

[Jim Lapenta]

The thing is that O2 cleaning a tank, especially an al40 or smaller is just crazy simple and can be done in about a 1/2 hour. The valve is more critical. There are nooks and crannies and twists and turns that have to be dealt with. Fortunately, since I O2 clean every reg I service (except the Edge EXP's since the kits are not viton) for myself or customers, I have all the items to clean the valves. The valve seats, however, are as John said, technically not O2 compatible.

 

[Chris H]

49CFR incorporates a number of CGA publications by reference. I'd love to have copies of them all. I find it especially irksome that they are incorporated by reference in federal regulations but not publicly available. Grrrrrr.....

You can purchase any of the CGA documents. They are around $30 each. And CGA loves to lock the PDF if you do find a copy.

 

[Scubagaskets]

Hi there All,
I saw that you are talking about Nitrox and Oxygen .
Just wanted to inform all of you, that scubagaskets has a special category for Viton Nitrox o-rings VITON Black FKM O-rings for Nitrox Sh 75-90 Archives - Premium O-rings Provider for Scuba Diving

and Viton O-rings Green FOR 100% Oxygen VITON Green FKM O-rings For 100% Oxygen gas Archives - Premium O-rings Provider for Scuba Diving

kind regards
Nicolas