how fast to empty a tank ?

[Kelly Jessop]

I had two LP120s burst disks blow within 2 minutes of each other at a fill station, with a fill pressure of 3300psig. We were lucky enough to be alert when the second disk blew,and we timed the complete evacuation of the cylinder to occur in 1 minute 12 seconds.

[Attchoum]

1.20 for a 120 ft cube and even more because it was overfill... seem logic

[Sam2000001]

A cheesy video, that I remember seeing a long time ago, but somewhat on topic: http://www.youtube.com/watch?v=2-dhP_jSO6I

[Bob Cree]

The key thing to realise is that the flow rate is related to the pressure in the cylinder. let's say it's directly proportional to pressure (this probably isn't quite true but it'll help make the point). Then the flow out would be exponential.

Hey Andrew - you have the right idea, but actually it is proportional to the square root of the pressure differential - so essentially the pressure, unless you are really really deep...which you actually might be...there are several fluid dynamic issues though, such as what happens when the velocity of the gas becomes super-sonic. The best method is to pop it off (a high powered rifle works great) and measure tank pressure versus time. Real time emperical.

It's okay to try this at home.