I'm a little late on this thread and might have missed it, but there's a sometimes confusing point about the ratings of LP steel tanks. A LP tank contains its rated volume of gas only when the pressure equals the rated pressure PLUS 10%!modivin:I guess I'm looking for the volume at, say, 3000 psi overfill for a standard 95 CF tank vs the 2640 overfill.
Using your example, assuming the 95 CF tank is a low pressure tank rated at 2400 psi, it will contain 95 CF only if it is filled to 2640 psi (that's 2400 plus 10%).
To find out how much gas it contains at other pressures, use the formula already provided and multiply the ratio 95/2640 by the pressure of interest. Here are some numbers for the example tank:
86 CF at 2400 psi (rated pressure); 95 CF at 2640 psi (rated volume, and rated pressure plus 10%); 101 CF at 2800 psi; 104 CF at 2904 psi (rated pressure plus 20%), 108 CF at 3000 psi. Try the calculations yourself and see if you can reproduce some of these numbers.
In my experience with LP overfills, I request 3000 psi, but what I get after the tank has cooled seems to be around 2800. For the example tank at 2800 psi, that's 6 CF (6%) more gas than the rated amount.