Racking on top of overcarbonated beer

I have .75 gallons of way way way overcarbonated Saison in a 2 1/2 gallon keg.  I was thinking of racking 1 1/2 gallons of beer from the same batch that just finished fermenting in a different carboy directly on top of it.  Do you think this will cause any unwanted reaction in the keg like turning everything to foam?  Any thoughts are greatly appreciated.

Where is the over carbonated beer? If it’s in a keg I would just vent it down. If it’s in bottles… I’d just chill the heck out of them before opening.

Yeah, I’d vent it down if it’s in the keg.  Release the pressure through the PRV , then close the PRV.  Agitate the keg a little to break gas out of the beer.  Let it sit for the foam to settle and the beer in the keg to equilibrate at its new level for a couple of hours, and repeat, until you get the carbonation down where you want it.  If you rack onto carbonated beer, you will be agitating it, and you’ll provide nucleation sites on yeast and hop particles, and it will be instant foam all over the place.

Thanks for the advice. Would you keep the regulator at 3 or 4 psi. Just to make sure you keep a little positive pressure after agitating and venting?

If clear beer that is just over carbonated is coming out now, I wouldn’t agitate. Just pull the PRV a few times over the course of a few hours, then try a pour again.

Good point.  I hadn’t thought that there might be sediment in the keg to kick up.  Thinking only of my own procedure where I only have clear beer in the serving keg.  (Having vent down a few times, I say from experience, will inspire you to find a more precise carbonation method.)

With that much dead space in the keg, it should be easy to vent it down. The question is - how did it get so overcarbed?

I was bottling from the keg with a beer gun for a competition. The style guideline says very high carbonation level with effervescent quality.  It was already carbed to a respectable level but I figured I’d lose a little in the bottling process so I cranked it up to 40 psi for 3 hours. I guess I should have checked it every hour or so.  If it was 5 gallons it might have been ok but .75 gallons at 34 degrees f with 40 lbs of pressure appears to carbonate rather quickly.

Did you pull the PRV prior to using your beer gun on it?  I can’t imagine that only 3 hrs at 40 psi would drastically add that THAT much carbonation to your beer…