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 Home Brew Forums > Foaming Issues...
07-15-2012, 04:54 PM   #1
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 Foaming Issues...

After a fair amount of research here and running through the balancing method from the Draft Beer Quality Manual I am still having foaming issues.
I usually get 2/3rds to a half glass of foam on the first pint and then it will run fine. When I come back for the next round though, I have the same foaming problem.

A couple thoughts:
When I ran the math from the DBQM I calculated I should have 3' 10" length beer lines. My beer lines are 10 inches too long. That didn't seem like enough difference to matter. I'll submit the math in a separate post.

I also have a tower cooling fan, but I have not been using it as I currently have three kegs in my fridge and I am quite short on space. When I was running it, it didn't seem to make much difference.

I used the burst carb method from the sticky to carb originally and I have cleared off the keg a couple of times but it did not make a difference.

What else should I be trying?

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07-15-2012, 05:00 PM   #2
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DBQM Math:
Target Volumes of CO2 - 2.5
Fridge Temp. - 40 degrees = 12.4 PSI
12.8 PSI

Static Resistance: 1.3 pounds
Middle of keg to tap = 31.5" at 0.5 pounds of resistance/foot

12.8 PSI - 1.3 static PSI = 11.5 PSI

Dynamic Resistance:11.5 PSI / 3 PSI per foot = 3' 10"

My beer lines are 4' 8" or 10" too long.

I think the extra length, if anything, should slow down the dispensing speed, not add foam - correct?

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07-15-2012, 05:03 PM   #3
stratslinger
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Anything that's suggesting you need 3'10" lines is suspect. What serving pressure and temperature are you using? Generally speaking, most folks around here use 10-12psi, around 40F, and right around 10 ft lines. I use 8 ft lines myself, and never have foaming problems. A buddy of mine uses 5 ft lines, and his first pint always pours with a bit too much head.

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07-15-2012, 05:59 PM   #4
bwarbiany
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I've been dealing with a similar issue, although mine is 10' line, in a keezer, with 3 fans for circulation. 40 degrees, 16 psi.

Interestingly, I've always used the burst carb methods. And all of those kegs are foamy. Some of them have been tapped for quite some time (months), so I would have expected overcarbonation to have dissipated if it ever existed.

But I just did my first "set & forget" carb, setting a keg to 16 psi about 8 days ago, and it's pouring absolutely spot-on perfectly. I don't know if perhaps I'll find that it'll start going foamy over time if it's not yet fully carbonated for 16 psi, but it sure seems to be dead on right now.

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07-15-2012, 07:01 PM   #5
JuanMoore
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Do not trust the line length calculators. They are designed for commercial systems which have very low serving temps, and they aren't accurate once the temp gets above ~36°F. The actual resistance of various lines also varies greatly between manufacturers, and even different production runs from the same manufacturer, so even at low temps those calculators really just provide a rough estimate, unless you happen to know the exact resistance of your particular piece of beer line. As you suspected, longer lines will only help. The only side effect of longer lines is a slower pour, so as long as you can fill a glass in a reasonable time, there's no such thing as lines that are too long. The calculators are also designed to give the fastest possible pour without excessive foam. I'm not running a bar where the number of pints I can pour in an hour impacts my paycheck. If I have time to drink a beer, then I also have a couple extra seconds to wait for it to pour

Your lines are definitely way too short for the temp and pressure you're using. As suggested above, 10' of 3/16" ID vinyl beer line is a pretty good starting point. You might even go longer if you plan on serving any beers with higher carb levels, and you'll also need longer if you're using other types of beer line, since they have less resistance than vinyl. After you get lines that are long enough, you may still have foaming issues since you're burst carbing. It's hard to dial in the carbonation perfectly when burst carbing, and if the carbonation ends up even a tiny bit higher than the carb level associated with your serving pressure and temp, you'll get foam for the first pour or two of every drinking session. If the lines, shank, or faucet are considerably warmer than the beer in the keg, you'll also get foam for at least the first pour or two of each drinking session.

Quote:
 Originally Posted by bwarbiany I've been dealing with a similar issue, although mine is 10' line, in a keezer, with 3 fans for circulation. 40 degrees, 16 psi. Interestingly, I've always used the burst carb methods. And all of those kegs are foamy. Some of them have been tapped for quite some time (months), so I would have expected overcarbonation to have dissipated if it ever existed. But I just did my first "set & forget" carb, setting a keg to 16 psi about 8 days ago, and it's pouring absolutely spot-on perfectly. I don't know if perhaps I'll find that it'll start going foamy over time if it's not yet fully carbonated for 16 psi, but it sure seems to be dead on right now.
If a keg is slightly overcarbonated it will pour foamy until enough headspace has been created for the excess gas to come out of solution. The overcarbonation can't dissipate unless the excess gas has somewhere to go. It has nothing to do with the length of time it's tapped, and everything to do with how much beer has been poured from it. If a keg is more than slightly overcarbed, there may not be enough space in the entire keg to hold the excess gas and get the carb level down to where it should be. If your kegs are overcarbonated, you can release the excess carbonation by shutting the gas off and pulling the pressure relief valve every time you think of it for a couple days. It's also possible that your 10' lines aren't long enough, since you're using a pretty high carbonation level. If you like the carbonation level you're getting now, you might consider lowering the pressure/carb level, since 8 days isn't enough time to fully reach equilibrium with your serving pressure.
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07-15-2012, 08:15 PM   #6
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Hi

I agree with all the stuff said above about lines and CO2.

Since you pour better on the second pour in a series, I suspect that your lines / shanks / faucets are warming up. The first pour cools them down and then the rest work better because they are at a lower temperature. A simple digital thermometer will help diagnose that issue.

Around here, all my faucets drip water constantly from condensation. The room is air-conditioned, but it's dew point is above 42 F - thus condensation. In a 75 F room you would have to have an RH below 30% to keep from getting any condensation at all with 42 F faucets.

Bob

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07-15-2012, 09:33 PM   #7
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Quote:
 Originally Posted by carlisle_bob Since you pour better on the second pour in a series, I suspect that your lines / shanks / faucets are warming up.
A carbonation level higher than what corresponds to the serving pressure and temp will result in the exact same behavior.
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07-16-2012, 02:57 AM   #8
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I agree- even though the calculator says 3'10" is right, it's about 6' too short.

I went from 6' lines to 8' lines, and then finally to 10' lines. Even if you don't "need" 10' lines, there is absolutely no down side. The worst thing that would happen with lines that are "too long" is it takes a few extra seconds to pour a beer.

I suggest two things- make sure that the lines are cold (same temperature as the keg) because sometimes kegerators with towers don't have a cooling method for the tower so the first pour is always foaming due to the warmer temperature in the lines of the tower. Second, longer lines. 10' would be about right. You could even go longer, and cut if the pour takes too long. But you can't make them longer so it's better to start longer in the first place.

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07-16-2012, 05:14 AM   #9
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Quote:
 Originally Posted by JuanMoore If you like the carbonation level you're getting now, you might consider lowering the pressure/carb level, since 8 days isn't enough time to fully reach equilibrium with your serving pressure.
I'm going to see what the "set & forget" keg does over the next week or two. Based on the line length calculators (I realize you say they're inaccurate), 16 psi and 10' lines should be fine as long as the lines are a resistance of ~1.5 lb per foot or so.

It truthfully was an accident to have 16psi on the regulator... But I'd personally prefer to have a higher carbonation level on the beer, and the calculator appears to support it. I had once tried dropping the pressure to ~12 psi, but was getting a bunch of bubbles in the line because the kegs were pressurized well beyond the serving pressure. Even now, at 16 psi, one keg still gets bubbles in the line, which I suspect means that keg is overcarbed even for 16 psi.

It seems to be getting better over time (FYI I have all 6 kegs on a manifold, and had just added two uncarbonated kegs to the system to "set & forget"). I would expect that some of the overcarbonation on those kegs 'helped along' the carbonation of the two new kegs.

This keezer build is new (~2 months now), so I'm still working it out... I'm hoping to keep in the 15-16 psi range though, but if the "set & forget" kegs go foamy, I'll have to dial it back and bleed out the excess.
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07-16-2012, 07:34 AM   #10
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Quote:
 Originally Posted by bwarbiany Based on the line length calculators (I realize you say they're inaccurate), 16 psi and 10' lines should be fine as long as the lines are a resistance of ~1.5 lb per foot or so.
That's just it, the resistance isn't going to be 1.5 psi/ft for you. Line resistance is not a fixed figure like the calculators would have you believe, but are actually a function of fluid velocity. Those figures are based on the maximum pour flow at 34°F that doesn't cause foaming (1 gal/minute). The warmer the serving temp the slower the pour needs to be in order to prevent the CO2 from coming out of solution. The slower the pour the less resistance the lines will have.
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