Kegerator - More foam than beer

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Kegerator - More foam than beer

Post by james1988 » Sun Dec 08, 2019 9:43 pm

Evening all,

I'm struggling with excessive foaming from my kegerator. I tend to serve stouts, pale ales along with the odd whit but I seem to be forever chasing the perfect pour (or even a good enough pour). My lines are 3/16" with the fridge temperature being around 10c, however (and this is the oddity) the beer inside the keg is 8c. I've measured both temperatures using an electronic thermometer that I've checked against another thermometer; both agree with each other.

My current pale ale has been carbonated to 15 PSI but is pouring with a massive head. I'm at my wits end at the moment, I've dropped the temperature of the fridge this evening so I'm hoping this will work.

Should I be pressurising to the fridge temperature or the beer temp? I've always assumed it was the beer temperature. Also, can anybody explain how the beer is at a lower temperature? I was always under the impression liquids can't drop lower than the ambient temperature or is that wrong?

Any advice is hugely appreciated.
James

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Re: Kegerator - More foam than beer

Post by f00b4r » Sun Dec 08, 2019 10:29 pm

Do you have some pictures of your setup, it might show something.
How are you measured those temperatures? If you are opening the fridge to measure the temperature it will be changing pretty rapidly, depending on ambient.
What is your equipment from keg to tap and what is your line length?
How are you carbing your beer and how long is it taking?

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Re: Kegerator - More foam than beer

Post by james1988 » Sun Dec 08, 2019 11:02 pm

Thanks F00b4r, will get something up tomorrow.

As for the temperatures, I'd left the thermometer in the fridge and shut the door for a few minutes (crude I know).

I then poured a sample of beer and measured that to get a reading from the inside of the keg. The thermometer is an instant read type so only took a second or two to get a reading.

I think my line lengths are 10ft or so but I'd have to check that tomorrow. It's 3/8 from the keg to a reducer and then 3/16 before reaching another reducer where it increases back to 3/8 and then the tap. I think those are the correct sizes for the lines, I've been running it for years and just putting up with the foam.

Carbing, I set the regulator to the desired pressure and then leave the keg at that pressure, normally for a few weeks.

James

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Re: Kegerator - More foam than beer

Post by LeeH » Mon Dec 09, 2019 6:13 am

Before you pour, have a look at your beer line. Can you see gas in line or is it just liquid?


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Re: Kegerator - More foam than beer

Post by IPA » Mon Dec 09, 2019 8:38 am

The reason that your beer is foaming is that it is over carbonated. It really is that simple. Correctly carbonated beer can be served from a tap fixed directly to the outpost. Forget all of that line length/diameter calculation nonsense that is just an attempt to cure over carbonation.
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Re: Kegerator - More foam than beer

Post by james1988 » Mon Dec 09, 2019 10:29 am

LeeH wrote:
Mon Dec 09, 2019 6:13 am
Before you pour, have a look at your beer line. Can you see gas in line or is it just liquid?


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Morning Lee,

I can see gas bubbles in the lines, I assume this is the carbon dioxide coming out of the solution.

James

PS poured a glass this morning, dropping the temperature hasn't achieved anything.

James

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Re: Kegerator - More foam than beer

Post by james1988 » Mon Dec 09, 2019 10:31 am

IPA wrote:
Mon Dec 09, 2019 8:38 am
The reason that your beer is foaming is that it is over carbonated. It really is that simple. Correctly carbonated beer can be served from a tap fixed directly to the outpost. Forget all of that line length/diameter calculation nonsense that is just an attempt to cure over carbonation.
Morning,

When drinking the beer it seems spot on as far as carbonation is concerned, I just get a massive amount of foam. I suppose though that the carbon dioxide coming out of the solution is helping that.

James

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Re: Kegerator - More foam than beer

Post by james1988 » Mon Dec 09, 2019 1:18 pm

Just had a look in the fridge, the beer was actually carved upto 10psi, so I've increased the pressure to 15PSI. Theres large bubbles in the lines so I'll leave it overnight and will have another look tomorrow morning.

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Re: Kegerator - More foam than beer

Post by LeeH » Mon Dec 09, 2019 5:53 pm

If you have a dodgy seal at the top of your dip tube that will cause the gas in the head space to mix into the liquid in your beer line.

Going from a very cold keg up into a warm font will also cause initial foaming.

Generally the issue is over carbonation but if you have controlled 3 variables (temp, pressure and time) to give you the desired volume the above is worth considering especially if you have bubbles in your beer line.



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Re: Kegerator - More foam than beer

Post by james1988 » Mon Dec 09, 2019 10:13 pm

LeeH wrote:
Mon Dec 09, 2019 5:53 pm
If you have a dodgy seal at the top of your dip tube that will cause the gas in the head space to mix into the liquid in your beer line.

Going from a very cold keg up into a warm font will also cause initial foaming.

Generally the issue is over carbonation but if you have controlled 3 variables (temp, pressure and time) to give you the desired volume the above is worth considering especially if you have bubbles in your beer line.



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That's one of my suspicions too. I'll let you know how it goes over the next few days, if all else fails I'll start swapping out bits.

James

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Re: Kegerator - More foam than beer

Post by Kev888 » Tue Dec 10, 2019 6:01 pm

Beer at around 8c and 15psi will be maintained at about 2.5 volumes of CO2 once it has found equilibrium. If it has then it is not over-carbonated from a dispensing point of view (and your preference is of course your own), but it is enough that the system needs to be set up pretty well indeed. (With lower levels of carbonation you can get away with less suitable arrangements).

There are several reasons why a system might not be ideal, some of which have already been mentioned. A common one is that the beer is not at equilibrium with the serving/dispensing pressure, but is actually more highly carbonated. E.g. because the yeast have unexpectedly carried on slightly in the keg, or because it was previously primed or force-carbonated to a higher pressure, or because the temperature of the beer is varying or has varied (it gets more highly carbonated if it gets cooler).

Other common ones are to do with the lines. Once the beer is at the intended level of carbonation and balanced by the serving pressure, then there needs to be enough restriction either in the line or in a flow-control to make the pour rate nicely sedate. The theory and calculators on line length are often over-simplistic IMO, you should go for the slowest pour that you can tolerate which may need rather longer line than currently or (if you prefer) the addition of a flow control.

If all the fundamentals seem well then try to look at where the foam is emerging in the lines, it might help shine some light on things. E.g. if it is as the 3/16 transitions back up to 3/8" then it may be worth moving the narrower bit to the tap end rather than in the middle.
Last edited by Kev888 on Tue Dec 10, 2019 8:28 pm, edited 1 time in total.
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Re: Kegerator - More foam than beer

Post by Cobnut » Tue Dec 10, 2019 6:25 pm

Kev,

Your reply here implies that serving pressure is not the same as carbonation pressure.

If I'm reading that right - and the implication I'm taking is "carbonate at a pressure higher than serving pressure" - surely if you dispense the beer over a lengthy period of time (probably typical for home bar setups) you'll lose carbonation as you dispense the beer?

I'm still quite new to kegging beer and finding for Engish style I need to set pressure to around 13psi @ c.6C (fridge temp) and leave it like that for a week or so and it seems to be carbonated OK (lowish levels) and pour nicely through the taps I use. Obviously higher pressures for hefeweisen, etc.

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Re: Kegerator - More foam than beer

Post by Kev888 » Tue Dec 10, 2019 8:24 pm

I think you've got it, if I understand you correctly: the temperature and pressure in the keg is related to how much CO2 is retained in the beer when carbonated. So if the serving pressure/temperature combo is set to a lower level than the beer is then yes, it will drop to a new lower level of equilibrium - as you say, it will lose carbonation.

But the CO2 levels will take appreciable time to drop, in some cases many days (unless shaken about). One effect of this is that serving at a given temperature/pressure is not the whole story to getting the serving setup balanced; the carbonation of the beer achieved is still important for quite a long time after connecting up to serve. If it is more highly carbonated than the serving conditions are set to balance, then foaming is more likely. A little like shaking a fizzy drink, as the beer passes over restrictions and joins etc in the beer line and drops in pressure towards the tap, these will help the CO2 levels to drop more rapidly - so it bubbles out causing foam.

My personal preference is therefore to have the serving conditions match those of the beer, so everything stays consistent throughout, and balance the lines for that. But some people choose to do it differently, or things can catch one out - yeast dribbling on, temperature changes and so on.

(and I've just noticed I said pore not pour in my last post :roll:)
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Re: Kegerator - More foam than beer

Post by james1988 » Tue Dec 10, 2019 10:43 pm

Thanks gents for the informative replies.

I think I might have gone wrong somewhere with temperatures and pressures. The reason I've gone for 15psi is because I prefer my beer warmer than stone cold (I like it around cellar temperature) but that means I'm having to crank up the pressure level to suit the warmer temperature.

So, looking at the formulas I think I've buggered up my pressures and beer line lengths somewhere.

If I have 10ft of beer line and I want 1psi at the tap, it would stand to reason the most I could get away with is roughly 10 / 11psi. Based on the formula on beersmith.com

L = (keg_pressure – 1 psi) / Resistance

It would seem the only way to balance this is to drop the temperature in the fridge to 6 / 7c in order to get a good pour which is a bit of an arse as I like my beer a bit warmer. The other alternative is to buy much longer lines to drop the serving pressure by the time it gets to the tap.

I've got flow control taps but they aren't working for me with the pressure level they're being subjected to (I can't imagine they were designed for a drop of 5 psi).

I think I've answered my own question...

James

Edit...

I've read some conflicting information about carbonation volumes...
Some guides say British Ales should be carbonated between 1.5 - 2.0 volumes whereas others say 2.2-2.6 volumes. My preference would be the lower volume which would mean I could increase the temperature in the fridge and decrease the pressure to less than 10 psi and, in theory, get a good pour (albeit slow).

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Re: Kegerator - More foam than beer

Post by Kev888 » Tue Dec 10, 2019 11:11 pm

The formulas also tend to suggest shorter lengths than I feel is ideal, partly because they assume a faster flow/pour rate than one might use if trying to control foam (and line resistance is actually less with slower flow rates).

Cellar temperatures are of course very suitable for many styles, and is how I like mine too, but 2.5 volumes of CO2 is perhaps more of a US take on normality. If that is your preference then fine, but otherwise it might be reduced somewhat to around 2.0 volumes or less - which might be 2/3rds of the current pressure, down to 1.5 volumes for some styles.

Though you shouldn't need to compromise too heavily on how you personally like the beer; rather than that, I would consider using longer 3/16" lines - in combo with the flow controls being used for finer adjustments.
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