how to? o2 cleaning tank valves

[rjack321]

The tank cleaning is the same for both 40 and pure . When you get a new tank you do not get a valve with the tank. Unless you get a O2 cleaned valve you do not have a tank valve combination that is O2 comatable. Most all vip stickers are out of date in regards to current federal regulations of 23.5%.

No one will sell you an O2 clean valve. They all cover their butts by saying <40% on a brand new valve using O2 compatible lubricants and hermetically sealed.

And as previously stated, scuba valves are inherently non-compliant when it comes to oxygen. They open way too fast and push HP O2 through a whole bunch of convoluted passages and over a big chunk of nylon which is marginally O2 compatible. So if you really wanted to parse this down you'd find that:
There is no way to make a scuba valve O2 safe per CGA standards as referenced by the CFRs.
ergo we should not and cannot put O2 into cylinders with scuba valves on them.

 

[NAM001]

Hopefully so, but given the crappy "homemade" VIP stickers out there the chance for ambiguity is certainly possible given that there are currently two standards air service and O2 service.

I recently saw a sticker that had the following three choices:

Breathing Air
Up to 40% O2 service
Up to 100% O2 Service

It says nothing about banked vs partial pressure filling. So it is ambiguous.

Though few and far between, there still can be and have been issues even with banked fills when the O2<40%. As such, many say the anecdotal evidence supports filling of bank O2<40% sans specialized cleaning. Which if that is the case why has there not been a standard introduced? And that is really my point.

If a shop wants to come up with their own standards so be it - not my problem. And not their problem until there is a problem. When they might find their standard has no backing and their insurance lets them deal with the problem themselves. And you can be sure any plaintiff's lawyer will be waving the CGA, OHSA, and other standards and asking why they were not followed.

And you have brought up the main point in O2 handling. Insurance coverage and liability is a law suit. You go to PSI and they will say their course is for the purpose of protecting you legally in the event of a suit. Not that the proceedures are effective or necessary to be safe. If 90% of the community says no O2 clean till above 50% and one says 22% they will say 22% is the line.

At the same time you have regs that say you cant fill a tank out of hydro date or transport a tank that has been filled out of hydro date, BUT you can transport a rust pitted tank that is filled and the hydro expired 50 years ago so long as the tank was filled when the hydro was good.

Nasa did the reaearch decades ago after they toasted the astronauts on the pad, They determined that 60% was the line of when O2 acts pure or like air. NOAAs gasses were 32 and 36 and allowed up to 40 for goofing the mix. Soi the 40% rulke was because of nitrox If Noaa was looking at a 50% mix 50% would have been the scuba rule cause it was below the 60% level determined by nasa. I personally do not believe in teh 23.5 standard but i legally have to. Reality and CYA are at war on this topic.

 

[NAM001]

It wont be that far down the road when only a very few vip stickers will be accepted. The home brewed stickers will be no good. When the day comes that an insurance co says to a shop you are on your own because the sticker on the tank was given subsequent to an inspection backed by a no standard. ie INDUSTRY STANDARD IS NOT A STANDARD. SCUBA STANDARD IS NOT A LEGAL STANDARD. ect. Untill like a PSI sticker says it is inspected and meets the requiremets set by cga ect the vip will not be excepted. I know of no one the has a legal Nitrox system, as per the O2 cleaning standards. I know of few that has certified fillers, fillng tanks, perhaps 25% are legit in training, then there is the hazmat training ect. When yo are done you probably find out that the owners 15YO is the inspector and it takes him less than 5 min to do a tank vip. I have watched this happen over and over agian. Said 15YO removes valve with a hammer tips tank upside down and looks for debris to fall out, smell teh tank and put on the valve again aadn apply sticker. In my view the 23.5 is the attempt to counter the poor inspections being done. If the line was still at 40+ then no nitrox tanks would get the level of attention that a n O2 clean provides IF DONE CORRECTLY. So its an integrity issue and not a physics issue, and yo cant legislate integrity.

 

[rjack321]

The reality is that unless the OP is going to fill the tanks himself, he should take his valve to the shop that will be filling them. They are the ones handling the O2 (if any). Let them clean them to their satisfaction.

Home cleaning and rebuilding valves based on what you learned on the internet and then giving them to a shop to fill (with O2) is just plain unethical.

 

[DEdiveguy1]

No one will sell you an O2 clean valve. They all cover their butts by saying <40% on a brand new valve using O2 compatible lubricants and hermetically sealed.

Only one will. Genesis Convertible 200 Bar Yoke/Din KA-70 valve. Comes in sealed bag from factory with O2 cleaned tag inside the bag. You're correct about the limitations stated from other manufacturers - Thermo, Sherwood, etc.

Only negative with the Genesis valve is that when it needs a rebuild, the kit price is 2X what you'd pay for any other valve overhaul kit.

 

[rjack321]

Only one will. Genesis Convertible 200 Bar Yoke/Din KA-70 valve. Comes in sealed bag from factory with O2 cleaned tag inside the bag. You're correct about the limitations stated from other manufacturers - Thermo, Sherwood, etc.

Only negative with the Genesis valve is that when it needs a rebuild, the kit price is 2X what you'd pay for any other valve overhaul kit.

I honestly didn't know you could still buy those! I have long since phased out all my genesis valves. At $39 for the DGX valves which accept the commonest HP seats, burst disks and no crush washers its totally worth it.

 

[Peter69_56]

Should use O2 compatible seats and viton O rings, along with the Simple Crystal Green (or similar), and not just use the standard components in off the shelf valves.


For valve seats;

Nylon 66 seats are not recommended for oxygen use, recommended for air. Usually standard in off the shelf valves.

Teflon Coated PVDF Insert recommended for Nx

Teflon Coated PEEK Insert recommended for oxygen higher hardness

Teflon Coated PCTFE&Carbon Insert best for oxygen high hardness

 

[Peter69_56]

It is not my definition rather a pointer to the industry standards. That said I find it funny you note OSHA being conservative and yet their standards except for the one for commercial applications (and does not apply to recreational scuba) are similar to the reset.

As for Blue Steel they note:

• Cylinders Oxygen cleaned for Nitrox use

Blue Steel Scuba - Faber Cylinders

Nitrox by is definition contains N2, 02, and a few other trace gases. But 90% O2, 10% N2 is nitrox.

I have also seen the following statement which probably what you are referring to: Faber steel cylinders are cleaned at the factory for oxygen-enriched service up to 40% pre-blended nitrox.

Which IMHO is a CYA statement because the while the cylinders are cleaned for oxygen-enriched service there is a specific limit on the gas. Which is the opposite of what you are trying to imply.

Quoted from an email I received from Faber when I asked if their tanks are oxygen clean from the factory "Please be informed that when the diving cylinders we manufacture leave our factory are internally oil free". From this you can assume that they are oxygen clean, however it doesn't actually say that. Also what happens to the cylinder after it leaves the factory is outside the control of faber. The middle man could remove the plug and contaminate? and as often is the case, fit the valve, the state of which is unknown. Thus the tank may be oil free, and perhaps the valve, but the valve seat is most probably nylon 66 and the valve may have been contaminated during the fitting process. I PP fill my tanks and clean and service the valve for O2 spec before filling with oxygen. This means I clean, replace seat and O ring on brand new valves prior to use.

 

[Peter69_56]

And people filling actual O2 know that and won't be putting 100% in there.

So I'm not sure what the big problem is?

Now you must be talking about a LDS I know. I had a cylinder inspected, hydro'd and cleaned along with the valve. After some use the valve got tight, and by this time I had done O2 clean course and Dive technician course. Opened the tank and valve, tank was putrid, and I had been PP filling it, valve was putrid and full of salt and corrosion with a nylon 66 seat. Clearly nothing had been done with this tank except stamp and fill.

All the subsequent fills were done with my compressor which is double filtered, so no contamination from other fills, and all my other tanks are spotless inside. Looks like the stamp and pay is here for some LDS with no conscience.

 

[Peter69_56]

I dont work in the industry, I just fill for myself and others I know. My rules are simple, I will PP fill if the tank is in date and showing an oxygen clean sticker, if any doubt, I will clean and service the valve at cost and clean the tank first. If that's not acceptable then the owner is free to go pay full price for a fill anywhere else but my home (I charge friends 2 cents/litre, dive shops here charge 6-6.5 cents/litre). If I am doing someone a favour, its under my rules as I am taking the risk when filling.

That's why I O2 service new valves. Most probably the valve is ok for oxygen when new, with exception of the seat and O ring, and the risk probably low, but for the cost and time to service the valve, I consider my life is worth that to make the effort. Then I know its OK.

I consider how happy I would be if I saved $12.55 in not servicing a valve as I lay in hospital with my face and arms with 3rd degree burns and my home burnt to the ground due to an oxygen fire. Yep worth every cent I am sure.

I try and keep the effort vs risk in perspective.