A Quick Question about tank capacity

[sheck33]

when comparing tanks keep the units in mind.
Pressure is measured in PSI (or Bars, atmospheres) and a volume of air is measured in CF (or liters).
PSI's are not a measure of volume.
If i know a tank has a pressure of 1500 PSI it tells me nothing UNLESS i also know what volume of gas the tank holds at it's rated pressure.

for example:

(ideally);
a HP steel 102 @ 1400 psi, an AL80 @ 1500 psi and a LP 104 @ 923 psi all hold roughly 40 CF of gas.

where HP is 3500 psi, LP here is 2400 psi and the AL is rated at 3000 psi.


make sense?

 

[Norda]

Here, check this out, its kind of fun to play with...

http://www.spearfishing.org/bruces_tips/tankv.html

You will need to know the rating of the various tanks, which has been posted on this board before, just do a search.

Bill.

 

[Arnaud]

You may also want to look at the fact that different sizes of tanks have different rated pressure.

As Sheck33 has explained it well , it's all about pressure and volume of gas at a given (rated) pressure. The pressure impacts the volume of gas since it is compressed...

If you want to know how much air you have in a tank, you need to know the volume of air it contains at its rated pressure. For instance, my tank will hold 119 CBFT of air at 3442 psi (rated pressure). If I only get a 3000 psi fill, my tank only contains...103 CBFT of air. And I need a calculator to find this one out.

In the rest of the world, things are a little easier. Tanks are measured by the volume of water (incompressible) they can hold. That's the same as the volume of air at 1 bar (or 1 ATM) at the surface of the sea.

So, a 15 liter tank at 200 bars will hold 3000 litters of air. That's much easier but that's another thread