Sorry, I may not have been quite as clear as I'd hoped.
What I'm attempting to get is a means of accurately understanding the quantity of gas (SCF) in a cylinder at any given Pressure (PSIG). I used the data I have, and tried to create a formula. It is a nasty cubic function, but it works...
I must preface this by saying that I am an automotive engineer who finds himself in unfamiliar territory. I am currently working on designing a mobile compressed natural gas (CNG) refueling system. As part of this project I'm being asked to estimate the behavior of our cylinders over the...