Originally Posted by DonkeyShoes
your 2nd gauge (reading tank pressure) will drop significantly. after 1 day in the fridge my gauge was in the "time to refill" range. has not dropped since.
Exactly! CO2 is in a liquid/vapor state that has a direct temperature/pressure relationship. The pressure will remain exactly the same, at a given temperature, until all of the liquid has been vaporized. Once only vapor exists, the pressure will drop rapidly. The pressure/temperature relationship can be seen in this PT chart for CO2.
The only downside, other than taking up space, of keeping the CO2 tank in the fridge is that the elastomer that the regulator diaphragms are made of will be slower to react to a change in output pressure when they are cold. For example, if you change the regulator output pressure from 10 psi to 12 psi when the regulator is cold, the pressure may slowly creep past 12 psi after some time has past. Over time, I learned to recognize the amount of overshoot and compensate for it.