The weight, volume, and space occupied is a static function across all gases - it's the noble gas law.

They sell you 20 oz of CO2 by weight and the volume and pressure are dictated by the size of the container it's in, which doesn't matter to me.


What I'm actually asking here is if people actually sell you 20 oz when they fill a tank and if they do, does the CO2 tank function to release gas for the entire 20 oz or does it fizzle out before the 20 oz mark.