Gettiing to 32%

[Dr. Lecter]

Not sure what point you think you're making, but if you think it's fine to leave the shop ignorant of the blend in the tank, and only important to analyze before diving that's fine by me. Personally, I want to know what I'm leaving with is--not hopefully, not probably, but actually is--and then double check everything at the site and/or as I'm loading regs onto tanks.


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[Superlyte27]

As moronic as this sounds, turn the tank over, then turn it right side up. Analyze. It might just read what you expected it to if it was recently blended.

Sounds ridiculous, and I used to clown on people who talked about this before I saw it myself.

Haha, I used to really knock on people who would roll tanks. Then I had a bunch of tanks all filled the same. I analyzed all of them, rolled half, then analyzed all of them again. It was amazing the results I got. Rolling really does work.

 

[kwinter]

There are plenty of posts on other forums stating that the need for mixes to settle is BS, that rolling the tanks around does absolutely nothing because of the high pressure inside and the mixing that goes on under pressure, and that filling the tanks while standing up is the reason for the differences and filling them while lying down on their sides eliminates the need to wait and roll them around.

Personally, I have tried every combination of things and the best mixer in the world is time. Entropy will have its way. Just don't rush it. If your shop does partial pressure fills, get them the tanks a couple of days before you need them. Or find a shop that does stick blending.

 

[Superlyte27]

Not sure what point you think you're making, but if you think it's fine to leave the shop ignorant of the blend in the tank, and only important to analyze before diving that's fine by me. Personally, I want to know what I'm leaving with is--not hopefully, not probably, but actually is--and then double check everything at the site and/or as I'm loading regs onto tanks.


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I think my point was pretty clear. This is English I'm typing right? My point, the whole point in everything I said in this thread.... Own an analyzer, check your gas before you dive. PERIOD>

 

[RJP]

How does the gas in the tank know which end is up? Is there something in the tank that moves the molecules around when the tank is rolled? Done a few VIP's but never seen any paddles or anything inside one. Is the friction between the walls of the tank and the immediately adjacent molecules sufficient to tumble all the molecules in the tank? If so, is it possible - if only theoretically - to roll the tank fast enough that centrifugal force can separate the heavier O2 from the infinitesimally lighter N2 molecules?

 

[Dr. Lecter]

It may be that it's the vibration of tumbling, rather than the rotation, that mixes the gas.

 

[LowDrag]

Completely normal minutes after filling. 4 hours later, if it was filled right, it'll settle out to 32%.

With that said, I won't dive anything without first analyzing it's final mix. This is the reason why everyone should own their own analyzers.

I believe the shop I go to has a bank system. Maybe that is the difference. It is probably already settled in by the time I have seen them fill a Nitrox tank and analyze it.

 

[dumpsterDiver]

How does the gas in the tank know which end is up? Is there something in the tank that moves the molecules around when the tank is rolled? Done a few VIP's but never seen any paddles or anything inside one. Is the friction between the walls of the tank and the immediately adjacent molecules sufficient to tumble all the molecules in the tank? If so, is it possible - if only theoretically - to roll the tank fast enough that centrifugal force can separate the heavier O2 from the infinitesimally lighter N2 molecules?

There is NOBODY who could make me believe rolling tanks makes a difference. I would have bet a significant amount of money that it is BS.. However, I've seen it with my own eyes... more than once..

 

[OrangeHead]

I used to find the idea ridiculous. But we forget how much gas is crammed into that cylinder. Go do a dry dive in a chamber, and see for yourself how thick the air is at just 6bar (say 84psi). At 200bar (2800psi) adding air to O2 won't be like farting in a lift (elevator), it'll be more like pouring the grenadine onto a tequila sunrise

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[TSandM]

Bill, the reason you were told not to put air in a Nitrox tank is that shops that don't pump Nitrox may not have the same standards of purity for their air as a shop does when it partial pressure blends. If the shop does partial pressure blending (putting O2 in and topping with air) they will have O2 clean air, so it doesn't matter what mix the tank has in it.