trimix diving

[ianr33]

if the gas didn't escape through the valve, the cylinder would have the same pressure in it a thousand years from now as it does today. It will have a few less molecules, however.

This is why its important to store trimix tanks upside down. The helium goes to the top of the tank rather than escaping out of the valve.

 

[Wookie]

This is why its important to store trimix tanks upside down. The helium goes to the top of the tank rather than escaping out of the valve.

D'oh! If you roll them, I hear they mix better.

 

[peterbj7]

You're funny too. Although helium atoms will migrate through the lattice of carbon steel cylinder walls, it happens on a molecular level, not on any practical level. In other words, it theoretically happens, but is not measurable. All things being equal, if the gas didn't escape through the valve, the cylinder would have the same pressure in it a thousand years from now as it does today. It will have a few less molecules, however.

Actually that seems not to be true. I discovered a part-used bottle of trimix that had been left over from a dive, and the tank not re-used for many months/a year. When I analysed the mix I found it down about 3 %age points from what it had been recorded and used at. Not a vast amount, granted, but certainly measurable.

 

[ianr33]

What's the accuracy on a helium analyzer?

 

[Superlyte27]

Only about a dozen things that could have come into play here...
lol...
I wonder why I keep logging in. Helium escaping through the sides of the tank. Geesh.
Rolling tanks to mix the nitrox. Wow.

 

[deepwater]

D'oh! If you roll them, I hear they mix better.

Roll them...crap I've doing it wrong all this time. I thought shaking them like a paint can was best.

 

[Wookie]

Roll them...crap I've doing it wrong all this time. I thought shaking them like a paint can was best.

Shaking like a paint can IS best. Next best is to get underway in 6-8's and keep the throttles firewalled. I hear crewboat driving is the best training...

I hear if yoiu roll the cylinders, the nitrox is better for deep diving, too.

 

[nerdkid]

do you guys actaullly shake or roll the bottle to mix the gases? omy..be serious! aahaha!

 

[Wookie]

do you guys actaullly shake or roll the bottle to mix the gases? omy..be serious! aahaha!

No. Those who understand gas laws do not shake or roll the bottle. It is just a joke. It is a trimix myth, like helium escaping from the cylinder (and oxygen and nitrogen not escaping) that seems to get a hold in some settings and never lets go. Wet filling cylinders to keep them cool is another such myth. (oooh, I opened a can of worms with that one)

 

[nerdkid]

hahahah! i see i see..yep i think you did..