Should I set spunding valve pressure for the colder fermentation vessel or the warmer serving keg?

[jtwilliams31]

Bit of a complicated question here as I'm new to spunding valve use. I want to carbonate via spunding valve, so I plan to set the pressure of my valve to the proper setting on a force carbonation chart for about 2.5 vols at my fermentation temperature. My problem is that I'm purging my serving keg with co2 during fermentation, but my serving keg is sitting at a different, higher temperature than my fermentation vessel. My fermentation vessel will be at around 65-67F while spunding, but my serving keg will be closer to 78-82F as it's warm in my fermentation room. I was curious if this difference in temperature would affect the carbonation of the beer itself or the pressure in the overall system?

As it currently stands, I have my fermentation keg in a mini-fridge with a line from the gas QD to the liquid QD on my serving keg (for purging) with the spunding valve set to 28 psi to carb to 2.5 vols. Is that 28 psi equal across both kegs? Does the warmer serving keg cause the pressure in the system to seem higher while it is actually lower for the fermentation keg causing lower carbonated beer? I'm a bit confused as I'm unable to keep both kegs at the same temp and I know that higher and lower temps affect pressure within the system.

 

[day_trippr]

 

[SanPancho]

Put the spunding valve in the ferm chamber, run the blowoff out to the serving keg.

Not an actual answer, but problem solved.

 

[day_trippr]

I may have missed a different type, but the "spunding valves" I've seen on HBT don't lend themselves to conveying the released gas to some kind of tubing or collector. They usually have 4 free air relief vents around the circumference, like this one:

Cheers!

 

[Vale71]

28 PSI is 28 PSI at any temperature. As long as the beer is really at the expected temperature it will reach the correct carbonation level.

 

[doug293cz]

I may have missed a different type, but the "spunding valves" I've seen on HBT don't lend themselves to conveying the released gas to some kind of tubing or collector. They usually have 4 free air relief vents around the circumference, like this one:

View attachment 689750

Cheers!

The Spundit spunding valve has a gas outlet barb that can be used to route the excess CO2 to a keg for purging. You will get better keg purging using atmospheric pressure CO2 rather than higher pressure CO2, so if possible put the spunding valve between the fermenter and keg being purged (and put an airlock on the outlet of the keg.)

The spunding pressure should be set based on the fermenter temperature, as it's the CO2 partial pressure in the fermenter headspace that will determine the level of carbonation, and it's the temperature of the liquid being carbonated that determines how much CO2 is absorbed at a given pressure.

Brew on