If you pull the PRV on a carbed keg until you don’t hear anymore pressure, is the beer still carbonated once you hook serving pressure up again?
Yes the beer is still carbonated. That just empties the head space.
If you want to decrease the co2 in the beer, empty the head space and then leave disconnected from the gas. co2 will come out of the beer slowly. It will take several days of relieving pressure and letting settle to make a big change in co2 level in the beer.
I wasn’t trying to relieve pressure, long story…