Tanks

[mtaylor]

You're looking at this from the wrong angle. How much air a tank holds is determined by both the volume and pressure.

At atmospheric pressure, a 68ci tank will hold 68 cubic inches while a 70ci tank will hold 70. When you start filling them, the same amount of air will end up being less pressure in the 70 cubic inch due to the higher volume, but when both are filled to 4500psi, the higher volume tank holds more air. To get an accurate volume of air, you need both the volume of the tank and pressure combined.