Buoyancy of full AL80 vs one with only 500 psi?

[nimoh]

Thanks Herman. Yeah, I misspoke about "weight". So from your experience the change is closer to 4 lbs? 5 lbs was something I'd heard from SOMEWHERE, just couldn't recall where.


Ok Bob, so with THOSE numbers how much air do we have in our tanks at 1000 psi, 2000 psi, etc? I'm assuming that the figures aren't linear (i.e. since 3k psi is 80 cu ft then 1500 = 40 cu ft, 750 psi = 20 cu ft, etc. I'm assuming that's not the case.)

or, more accurately

3000psi = 77.4 cu ft
1500psi = 38.7 cu ft
750psi = 19.35 cu ft
500psi = 12.9 cu ft (19.35 * 2/3)

 

[dfx]

For those used to metrics
1 m³ of air weighs 1.20 kg at 20°C

or 1.20 grams per liter, as 1 m³ = 1000 liters.

 

[ganu76]

... and this is why I like this place so much. Just so much knowledge out there.

---------- Post added September 24th, 2013 at 06:39 PM ----------

So it looks like the bottle's actually buoyancy with 500 psi is a positive 3 lbs above neutral, with a total swing in buoyancy being 5 lbs (-2 lbs at full to +3 lbs at 500 psi).

Rough and approx numbers but that's where we are right now, righr?

---------- Post added September 25th, 2013 at 07:23 AM ----------

This has raised another question. Are these numbers good for both fresh water and salt? Obviously the starting and ending values will be different but wouldn't the 5 lbs change in buoyancy remain constant?