Tank Mathematics

[GuardTrash]

Does anyone know the mathmatical formula to figure out how many cubic feet is in your tank at whatever pressure it is? Lets say you have a HP100 and at 3500psi it has 100 cubic feet of air in it, well how many cubic feet does it have when it is 2300psi? Maybe this has already been dicussed but I couldn't find it. Its just a gee-whiz sort of thing I wanted to figure out.

 

[captndale]

V = 100CF * P / 3500 psi

 

[Nitroxnut01]

I use:
CuFt = PSI x Rated Capacity/Rated Pressure
Cuft = 2300x100/3500= 230,000/3500=65.7 cuft

 

[Doc Harry]

Check out this thread on this very topic from this very forum from yesterday

http://www.scubaboard.com/forums/tanks-valves-bands/306088-tank-fill-question.html

 

[HowardE]

Simple answer - You have to calculate how many cubic feet you have in each 1 pound per square inch of gas. You need to know the full tank capacity aka service pressure (listed on tank).

a) Calculate how many cubic feet per psi you have when the tank is full.
100cubic feet/3500 psi = .029 cubic feet / psi

2) Multiply your cuft/psi by the number of psi you actually have
.029 (cubic feet per psi) X 2300 psi = 65.7 Cubic Feet.

 

[The Kraken]

100 cubic feet at 3500 psi

3500 divided by 100 will give you 35 psi per cubic foot.

So if you have 700 psi (35 psi X 200) then you have 20 cf (700 / 35).

Basic math.

the K

 

[Jim Baldwin]

Does anyone know the mathmatical formula to figure out how many cubic feet is in your tank at whatever pressure it is? Lets say you have a HP100 and at 3500psi it has 100 cubic feet of air in it, well how many cubic feet does it have when it is 2300psi? Maybe this has already been dicussed but I couldn't find it. Its just a gee-whiz sort of thing I wanted to figure out.

This is something that does get asked asked quite often.

Tank pressure divided by working pressure times cubic feet of the tank equal remaining cubic feet.


2600/3500 = .742 X 100 = 74.2 cu. ft.

If you had an overfill

4000/3500 = 1.14 X 100 = 114 cu. ft.

 

[GuardTrash]

Thanks for all for the replies. Seems kind of easy to figure out now that I see the formulas.

 

[The Kraken]

No problem. It can all be kinda smokey when you're relatively new.

Safe dives . . . . . . . .
. . . safer ascents ! ! !

the K

 

[Cave Diver]

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