Bottle Sizes?

[David H]

OK.

So, an O2 bottle is labeled 337cf and the bottle is stamped 3AA2400 with a plus rating. So, is it a ~300cf bottle (per my internet research) at rated pressure of 2400 psi, and only a 337cf bottle at 2640?

On the same idea...why is the same physical bottle only a 291cf bottle for He? O2 comes in at ~2400 psi and He comes in at 2640.


And now the really fun part:

Those silly 3AA3500 and 3AA3600 bottles. How in the world do I figure out how many cu ft these hold at rated pressure?



Thanks! I haven't done physics in a long time

[rjack]

These pages should help:
L water capacity x service pressure in bar = capacity in L

Standard cylinders up to 3600psi
http://www.taylorwharton.com/Pages/H...20pressure.htm

"Lightweight cylinders" 4500 and 6000psi
http://www.taylorwharton.com/Pages/H...%20Weights.htm


Differences in gas compressibility will have the same cylinder holding slightly different amounts depending on contents. Unfortunately it's a non-linear relationship with pressure so there's no easy translation.

But generally O2 is about 10% more compressible (when expanded it fills 10% more volume) than air. Helium is about 10% less compressible than air (take same pressure in identical tanks and there will be 10% less volume of He when expanded to 1 ATA). These rules of thumb apply to the typical 1500-3500 pressure ranges. Errors increase above that.

So my recommendation is to take the water volume X service pressure in bar to calculate total volume in L. Convert to cubic feet if you want. Add 10% for O2, subtract 10% for He.

Richard

[seavonj]

I get all of my gases through Aeris here in Northern CA, every bottle I get has a sticker on them with the cft in the bottle, i figure it out just like you would for scuba bottle and that I find the tank factor for given cylinder. Makes things easy when PP blending. If that is what you are doing of course.