Serving question

[jessebaseball]

Hi I am enjoying my 2.5 gal corney keg with a barqs root beer bag in box set up. I carbonate the water to 55psi for 2 days and I leave it as is. I don't drop the pressure at all. I'm serving the water in a mug than add the syrup. I disconnect and reconnect the picnic tap to prevent leaking.

My questions are this. When the water is fully carbonated, will it go flat if I drop the psi to abut 15 and bleed of pressure from the keg?

 

[MrFoodScientist]

Yes, it will equilibrate to whatever volume of CO2 is soluble in water at whatever given temperature you have your keg stored at.

It would be the same as opening up a two liter and closing it back up again. Gas will come out of solution to re-pressurize the headspace until it reaches equilibrium. So maybe the first time you vent (depending on headspace), your keg may repressurize itself to 52psi after a while. Then you vent again and it repressurizes to maybe 48psi or whatever will fill the headspace.

It won't stay carbonated at the same level unless it's held at the same pressure/temperature.