Oxygen Clean Tank Valves

[boulderjohn]

The last time I certified as an inspector with PCI, they said that no matter what you do to a K-valve, it cannot truly be approved for oxygen service because of the number of turns the gas must take. They didn't offer a solution other than to realize that limitation when you approve a cylinder as oxygen clean anyway.

When the dive shop where I was working bought some Thermo isolation manifolds and prepared to set up doubles, we noted that the information that came with them said that they can never be used for mixes greater than 40%, no matter what you do to them. Since we would be making trimix through partial pressure blending, that was a problem for us. We called, and the Thermo guy confirmed that they could not be used for greater than 40% and, in fact, no such valves could be used for greater than 40%. As he talked, you could almost hear the CYA winking.

 

[LanceRiley]

Doing all that to any valve will make it O2 clean-ish. You can verify contamination status in a few different ways, but that is pretty much the process for O2 cleaning something.

Thanks this is what i meant…


any nitrox ready valves can be oxygen cleaned without replacing the existing bnew viton orings by just degreasing everything then using oxygen compliant grease

 

[LanceRiley]

The last time I certified as an inspector with PCI, they said that no matter what you do to a K-valve, it cannot truly be approved for oxygen service because of the number of turns the gas must take. They didn't offer a solution other than to realize that limitation when you approve a cylinder as oxygen clean anyway.

When the dive shop where I was working bought some Thermo isolation manifolds and prepared to set up doubles, we noted that the information that came with them said that they can never be used for mixes greater than 40%, no matter what you do to them. Since we would be making trimix through partial pressure blending, that was a problem for us. We called, and the Thermo guy confirmed that they could not be used for greater than 40% and, in fact, no such valves could be used for greater than 40%. As he talked, you could almost hear the CYA winking.

So what are we doing oxygen cleaning our valves for pp blending?

 

[rjack321]

So what are we doing oxygen cleaning our valves for pp blending?

We're doing the best we can with the (fast opening) valves we're forced to accept.

 

[LanceRiley]

We're doing the best we can with the (fast opening) valves we're forced to accept.

heheheh

i had 2 not oxygen cleaned deco regs. 1 was for 50% nitrox and the other 100%.

i oxygen cleaned it after a few dives… but take note did a few dives with it while being not oxygen cleaned. Just opened it really slow with purge pressed.

 

[boulderjohn]

So what are we doing oxygen cleaning our valves for pp blending?

We're doing the best we can with the (fast opening) valves we're forced to accept.

If you really look at all the supposed rules pertaining to oxygen cleaning, it would be close to impossible to follow them all. In fact, according to my training, it is the path the oxygen must take, not just the speed at which it takes it, that is the concern.

So we do the best we can.

I have talked to people about this in my instructional past, and I learned I have to make it as clear as possible that knowing that it is impossible to be 100% compliant does not mean you don't have to do anything at all. You do the best you can.

 

[Micko1974]

Dive gear express covers this pretty well through a few articles. This is a good place to start:

Understanding Nitrox Ready and Oxygen Service | Dive Gear Express®

Understanding Nitrox Ready and Oxygen Service Can I use it with Oxygen? Yes and no; this simple question has a complex answer because there is no widely recognized scuba diving standard for ...

www.divegearexpress.com

Thanks for sharing these articles. They are really informative.

 

[Jersey1971]

Hypothetical question, if one were to fill an O2 clean tank with a regular Transfill whip, should that tank be immediately condemned and taken to the nearest landfill?” Or can it’s O2 clean status be redeemed? And if it’s recklessly used with, say 50% nitrox, what is the risk of a conflagration?

 

[LanceRiley]

Hypothetical question, if one were to fill an O2 clean tank with a regular Transfill whip, should that tank be immediately condemned and taken to the nearest landfill?” Or can it’s O2 clean status be redeemed? And if it’s recklessly used with, say 50% nitrox, what is the risk of a conflagration?

that's just it.. an oxygen clean tank ang valve....

when you do partial pressure blending, oxygen is transferred first....

but then you need to top up using your regular compressor.... unless your so sure .... that your compressure is not spewing anykind of oil at any minute qty... then its theoretically still clean... until its not...


hence all my question about how oxygen clean do you wana go? 40% bnew valves. are.. what they are 40% but they are technically cleaned.... for oxygen...

 

[Tom_Ivan]

That's a good point. We often hear people says things like "if you put a non O2 cleaned regulator onto your tank, your tank is no longer O2 cleaned". But what about when you hook up your compressor while PP blending?
Or do people have fancy compressors when nitrox filling?

Side question, is it big explosions that we're primarily concerned with when dealing with O2 or are we worried that there will be small scale combustion in the cylinder/valve that puts high CO in our breathing gas?