Second Pour Foam

day_trippr said:

12 psi would be proper if the beer temperature is ~42°F.
At equilibrium that would result in ~2.4 volumes of CO2, which is about right for a wide range of styles. Otoh, 7-8 psi would result in just under 2 volumes, which would be on the low side for most styles.

In any case, the whole point of the 650 Perl is to obviate the need for resistance provided via line length - which ought to mean it can control for pressure differences.

As for the OP's issue: if there's no CO2-breakout in the lines, the problem doesn't vary with line length or beer style (or, presumably, kegs used), and it affects multiple faucets, plus a "quick" second pour is unafflicted, it does seem that you have a thermal issue with your dispensing setup.

That said, now I'm hoping you have an uncooled tower or coffin, or your faucets are through a wall or something exotic, because if your faucets are mounted in a keezer collar or through a fridge door/wall, that's going to complicate diagnosis even more...

Cheers!

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splyn said:

So i built my keezer with three Perlick 650ss taps. the keezer is kept at ~42F , kegs are pressurized to 12psi and the lines vary from 5' to 11'. when i grab my first pour, i usually get a few ounces of foam (i attribute this to a room temp tap), which i drink then fill my glass normally and get decent/great pours. however, when i return for my second glass, there is significantly more foam than the first pour. can anyone help to explain this? this happens regardless of line length, which tap is being used, style, etc. I have have no leaks inside the poppets, and no CO2 is coming out of solution in the lines. the time between the first and second pours does give the tap ample time to warm up to normal temp after being chilled by the first pour.

More curious than anything else, but i would like to eliminate this annoyance.

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kev211 said:

Thats one thing if he's carbing at 8 psi vs 12 psi but 8 seems to be fine to push with. Ive always done that and have had no issues with losing carbonation over time or otherwise. I agree, the thermal diagnosis makes sense, but at first observation 12 psi seemed really high as a dispensing pressure

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day_trippr said:

But, you do realize that you are losing carbonation over time, yes? The physics are undeniable.

And that's the long and short of it: the optimum solution is to design a dispensing system to allow the combination of beer temperature and CO2 pressure to both maintain the desired carbonation level - and provide a quality dispense.

I carb at 11 psi, and my keezer is tuned to allow an 11 psi dispense. It'll actually handle up to 13 psi before even the slightest degradation in pour quality is discernible...

Cheers!

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