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capacity at xxxx pressure

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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sl33py

New Member
Jul 29, 2004
3
0
0
46
not sure if this is the correct area, but seem to have some pretty smart fellas (and ladies).

how do you figure out the volume in cubic feet of a cylinder at a specific pressure? I can roughly figure it out, but specific to a cylinder...

so if a e8-130 is at 3442psi and has 130cf, at 3800psi i get ~148.2cf. am i even close?

is there an easy formula that might help? It's been a long time since my physics class...talk slowly. hehehe.

i am looking for an easy way to figure the cf of say an aluminum 80 @ 3000psi, or a HP 80 @ 3800. I imagine knowing the volume is going to be the real ticket, but can't seem to figure it out.

thanks! sorry for the random post...

sl33py
 

efattah

Well-Known Member
Mar 2, 2001
3,294
487
173
Air doesn't compress linearly at such high pressures, because the ideal gas law doesn't hold anymore. You'll either have to use the Van der Waals equation or use a chart.


Eric Fattah
BC, Canada
 

tom yerian

New Member
Sep 26, 2004
43
0
0
75
to do the math:
cft/working pressureXnew working pressure

80/3000x3500+93.33cft: The new working pressure is now, 93cft. You would round down. This is part of a gas planning procedure you would in use in planning dives. To do this, you would have to know how to calculate your RMV(respiratory minute volume) to plan your gas usage.
If you need any further help, please write me back and I will help you grasp the principles of the math involved.

YID: Capt. Tom Yerian
 

FreeFloat

Underwater Tourist
Jun 5, 2003
114
29
0
Keep in mind also that a 'typical' AL80 contains only 77.4 cuft of gas at 'working' pressure (3000 psi)......
 

tom yerian

New Member
Sep 26, 2004
43
0
0
75
These formulas are for technical oriented divers that have some knowledge of planning and use of dive -planning tools such as these math tools.I say one step at a time, learn function first!!! Then apply precision.To this diver I might add, multiply their answer by 1.5The diff. was only 3cft and i said to round down to 90cft.!If they are interested in planning gas use they will write me back.That was an example not a total empiricle answer!!

YID: Capt. Tom Yerian
 

mic couzens

New Member
Dec 8, 2004
14
0
0
59
tom yerian said:
to do the math:
cft/working pressureXnew working pressure

80/3000x3500+93.33cft: The new working pressure is now, 93cft. You would round down. This is part of a gas planning procedure you would in use in planning dives. To do this, you would have to know how to calculate your RMV(respiratory minute volume) to plan your gas usage.
If you need any further help, please write me back and I will help you grasp the principles of the math involved.

YID: Capt. Tom Yerian
did you get my last mail mic
 

tom yerian

New Member
Sep 26, 2004
43
0
0
75
mic couzens said:
did you get my mail on my certs ext mic

No, I did not find them listed. This forum is a little bit of a task to understand. I write in respo to one thing and get diff.replies to other things. Write to me at my email address and maybe I will get the thing right!

YID: Capt. Tom
 
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