Cascade System question/ Info

[tbone1004]

Fill and empty them a couple times so the percentage of N2 inside drops near enough to atmospheric as makes no difference.
Fill them again with suitable air, and then fill your tanks from them.
Then, go blow some bubbles.

I wouldn't bother with step 1.... It's N2, just drain it all the way down and don't worry about it.

 

[Kirk king]

This is a complete load of...well, "disinformation." Atmospheric air is 79% N2 fer cryin' out loud. I did not look up the CGA valve spec for inert gas vs. air, but the valves are not that expensive if you bother to change them. (I would change them if they weren't the same, but that's me.) If you want them to be "the right color for air," buy a can of spray paint. Blue, IIRC.

Tanks are tanks and N2 is harmless, and does not dissolve in steel to any significant degree. It will not somehow contaminate breathing gas afterward. Buy the N2 tanks. Inspect them. Fill and empty them a couple times so the percentage of N2 inside drops near enough to atmospheric as makes no difference. Fill them again with suitable air, and then fill your tanks from them. If you need O2-clean air, clean them first or have them cleaned *no matter what they were used for previously*. (Actually that's not a bad idea in general.)

If you will pump them and your dive tanks full of air only, you need not analyze, either, except possibly the first time to assure yourself O2 levels are normal after the purging is done. If you will mix, on the other hand, you need to analyze without fail.

Then, go blow some bubbles.

the valves in them are CGA 677 rated for 6,000 psi

 

[Billy Northrup]

I would change out the valves for consistency at minimum, paint them for the hell of it.

Now if they had something nasty in them before like hexamethyldeath no way.

 

[TrimixToo]

I wouldn't bother with step 1.... It's N2, just drain it all the way down and don't worry about it.

I'd purge them a few times anyway unless I knew the purity of the prior N2 fill, and I should have added that. But again, that's just me. Air is cheap...

 

[Kirk king]

I'd purge them a few times anyway unless I knew the purity of the prior N2 fill, and I should have added that. But again, that's just me. Air is cheap...

the cylinders are filled with 99.995% nitrogen so pure of the pure....

 

[TrimixToo]

the valves in them are CGA 677 rated for 6,000 psi

I'd change them, as I said. You can just buy the right nipples and nuts and use them as-is, which is cheaper and would work fine, but if they ever "make it back into the wild" with the wrong valves on them, it's possible--however unlikely--that someone could get hurt as a result. Also, new valves come with new seats and they are already clean...

 

[Jack Hammer]

At minimum I'd remove the valves and look inside before using them, just to be sure everything looks good.

 

[tbone1004]

changing valves in these bottles is a complete and utter PITA so if you can get the supplier to swap to CGA347 for air if they will, and if not see if they'll go to CGA580 which is helium and nitrogen

 

[Jack Hammer]

Oh yeah, and as long as you're analyzing... dont forget to check for Carbon Monoxide.

 

[Wookie]

Even better, send them for hydro, swap the CGA 677 for 347, rinse with blue-gold and use for air.

Oh, I said that already.