Blending EANx40 in AL40's

[maxguru]

Has anyone besides me noticed that mixing EANx50 in an AL40 works better if the tank is laid down, rather than standing up?

If so, could you posit a reason why?

Max
DSAT 198186

 

[Dive-aholic]

I've had no problems and I stand my tanks upright.

 

[ucfdiver]

Excuse my stupidity, but why would it matter? Furthermore, how would you even know if it were off, since you can only measure off the valve?

 

[Tortuga68]

I've only blended upright tanks, so no I haven't noticed any difference (nor issues)

What do you mean by 'works better' and what blending method are you using?

 

[DA Aquamaster]

I have noticed that if I partial pressure blend EAN 50 in a tank (in this case 40 cu ft deco bottles) and use very slow fill rates, I usually have to roll the tank on the floor for a couple minutes to get an accurate analysis.

I doubt mixing in a skinnier bottle makes a diffrence, but the slow fill rate does and if you think about it, "slow" is a lot slower in terms of gas flow in a small tank where 50 psi per minute in a 40 is about half the volume of gas as 50 psi per minute in an 80. I suspect less volume/gas flow results in less turbulence and mixing in the tank and as a result more stratification of what you put in first and last.

I have found that if I put the last 100 psi in fairly rapidly I get an accurate analysis off the bat with no need to roll.

Laying flat versus vertical would just change how "deep" the stratification is and places the valve in the middle of the stratification, not on an extreme end.

 

[Superlyte27]

I have noticed that if I partial pressure blend EAN 50 in a tank (in this case 40 cu ft deco bottles) and use very slow fill rates, I usually have to roll the tank on the floor for a couple minutes to get an accurate analysis.

I doubt mixing in a skinnier bottle makes a diffrence, but the slow fill rate does and if you think about it, "slow" is a lot slower in terms of gas flow in a small tank where 50 psi per minute in a 40 is about half the volume of gas as 50 psi per minute in an 80. I suspect less volume/gas flow results in less turbulence and mixing in the tank and as a result more stratification of what you put in first and last.

I have found that if I put the last 100 psi in fairly rapidly I get an accurate analysis off the bat with no need to roll.

Laying flat versus vertical would just change how "deep" the stratification is and places the valve in the middle of the stratification, not on an extreme end.

LOL, that's funny.

 

[sea2summit]

I've noticed problems filling trimix like this. Never tried setting the bottles on their side but I did start shaking them before analyzing and it seemed to fix it. I'm sure if you didn't analyze right away it would self correct.

 

[rjack321]

I have noticed that if I partial pressure blend EAN 50 in a tank (in this case 40 cu ft deco bottles) and use very slow fill rates, I usually have to roll the tank on the floor for a couple minutes to get an accurate analysis.

I doubt mixing in a skinnier bottle makes a diffrence, but the slow fill rate does and if you think about it, "slow" is a lot slower in terms of gas flow in a small tank where 50 psi per minute in a 40 is about half the volume of gas as 50 psi per minute in an 80. I suspect less volume/gas flow results in less turbulence and mixing in the tank and as a result more stratification of what you put in first and last.

I have found that if I put the last 100 psi in fairly rapidly I get an accurate analysis off the bat with no need to roll.

Laying flat versus vertical would just change how "deep" the stratification is and places the valve in the middle of the stratification, not on an extreme end.

Same issue here, 3cfm for the air top is "too slow" to generate much turbulence and the warmer air straight out of the compressor will sit on top of the cooler O2 (which almost always sat overnight) for quite awhile. Laying them down works or leaving them for a day. If I had a bigger compressor or topped them off from air banks I doubt I'd notice the stratification.

 

[dannobee]

So have any of you guys PP blended two tanks side by side, with one standing up then leaving it alone, and the other laying on its side then rolled it afterward? Then analyze them both over similar periods of time to collect data points.

I'd be curious to know if it's just the time element that is the variable and not the rolling or attitude of the tank.

We bank 32% which is partial pressure blended. It takes a while for the gases to homogenize, and we certainly don't roll or lay 12 bank bottles on their sides.

 

[rjack321]

I bought some new bank bottles (>500cf worth) once and hooked them up with the right amount of O2 remaining. Air topped them from my little 3cfm compressor and it took the better part of a week for them to analyze out at 32%.