Author Topic: Pressure difference between kegs  (Read 788 times)

Online dolecek21

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Pressure difference between kegs
« on: October 29, 2013, 04:51:51 PM »
Hi all,

I've had a problem lately (and maybe previously, but not to the degree) with seemingly a pressure difference between two kegs. My system consists of one CO2 tank and one regulator that goes to a 3-port manifold. Currently two of the ports on the manifold go to kegs, the third is closed (no line). One of my kegs seems to pour under a significantly higher pressure than the other. Could the difference in beer levels in the kegs cause this? While it seems plausible to me that it could cause a difference, it seems as though it would be small.

Adding to the problem is that the keg with the higher pouring pressure is leaking out of the cobra tap (which luckily I found after only a few beers worth were on the floor of the freezer). The regulator is set to 10 psi, which in my experience should be pretty typical and low enough that there shouldn't be a leak at the tap.

Thoughts?

Thanks!


Offline Steve in TX

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Re: Pressure difference between kegs
« Reply #1 on: October 29, 2013, 05:16:41 PM »
Could the keg with issues be carbed higher? Do you set and forget carb or fast carb.

Online kramerog

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Re: Pressure difference between kegs
« Reply #2 on: October 29, 2013, 05:35:43 PM »
Are the lines the serving lines the same length?
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Offline repo

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Re: Pressure difference between kegs
« Reply #3 on: October 29, 2013, 09:57:29 PM »
I had a diptube that was just too long, when tightened (over?) it would touch the bottom of the keg and cause the beer to come out gushing. I  was able to loosen the fitting enough to finish the keg and then shortened the tube.

Offline jamminbrew

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Re: Pressure difference between kegs
« Reply #4 on: October 30, 2013, 06:14:31 AM »
Is it possible that the beer in the overcarbed keg might not have been finished fermenting?
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Offline Joe Sr.

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Re: Pressure difference between kegs
« Reply #5 on: October 30, 2013, 07:32:38 AM »
I had a diptube that was just too long, when tightened (over?) it would touch the bottom of the keg and cause the beer to come out gushing. I  was able to loosen the fitting enough to finish the keg and then shortened the tube.

This is what occurred to me.  The dip tube could be obstructed on one of the kegs.

If you want to test the manifold, switch the gas lines on each keg and see if it changes the serving pressures.  If so, there's some issue with the manifold.

Beer level in the keg should not have an effect.
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Offline morticaixavier

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Re: Pressure difference between kegs
« Reply #6 on: October 30, 2013, 07:35:44 AM »
Is it possible that the beer in the overcarbed keg might not have been finished fermenting?

+1 the fact that you say the cobra tap is leaking on that one makes me think that you've got more pressure than 10 psi in that one. When you pull a beer from it do you hear more gas going in? if not than it's making it own.

I have also had problems with popits that were too tall and I can imagine a too long dip tube would be similar.
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Online dolecek21

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Re: Pressure difference between kegs
« Reply #7 on: October 30, 2013, 12:18:48 PM »
Thanks for the help!

Both of my serving lines are the same length, and both kegs were "set and forget" over a week to begin with. I tapped one (APA) 4-5 weeks ago, and the second (AIPA) 2-3 weeks ago. One of the most interesting things is that the first (APA) was pouring at a seemingly higher pressure in the beginning, and now it is the second (AIPA). This is what made me wonder if the beer levels had something to do with it (as I mentioned I lost some of the IPA due to leaking). I agree that I don't know why that would be though.

A dip tube length problem isn't some thing that I have thought of, thanks for the suggestion! I haven't noticed any problems with either of these kegs in the past, but maybe while hooking up the serving line I somehow twisted the dip tube so that it is up against the wall at the bottom of the keg? I haven't cut either dip tube. Maybe I'll try turning the line at the ball lock while pouring to see if I notice a difference.

I'd be surprised if either were still fermenting, and creating the pressure. Mostly due to the time that has already gone by, and both having poured at a regular rate at some point. I also typically keep my beers in the primary for a few days after signs of fermentation have stopped and the krausen has dropped.

Thanks again!

Offline Joe Sr.

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Re: Pressure difference between kegs
« Reply #8 on: October 30, 2013, 12:24:40 PM »
Have you sprayed the lids with starsan to make sure you have no leaks?  The lid seal could be leaking and/or the pressure relief.
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Offline klickitat jim

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Re: Pressure difference between kegs
« Reply #9 on: October 30, 2013, 12:28:59 PM »
Seems like it would follow the path of least resistance so it might not take much of an obstruction to create a noticeable difference.

Offline gmac

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Re: Pressure difference between kegs
« Reply #10 on: October 30, 2013, 12:36:15 PM »
Is it actually more pressure or is it foaming more? Those are two different things. 
I'd try turning off both, venting both kegs and then turning one on and let it come to regulator pressure, pouring it and the do the same with the other and see what you get.  Since you would have vented both, the only pressure should be what you put in at that moment and thus excess foam would be a blockage (tube, poppit or maybe junk in the poppit/tap).

Offline dkfick

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Re: Pressure difference between kegs
« Reply #11 on: October 30, 2013, 01:19:24 PM »
Is it actually more pressure or is it foaming more? Those are two different things. 
I'd try turning off both, venting both kegs and then turning one on and let it come to regulator pressure, pouring it and the do the same with the other and see what you get.  Since you would have vented both, the only pressure should be what you put in at that moment and thus excess foam would be a blockage (tube, poppit or maybe junk in the poppit/tap).
+1 to this.
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Online dolecek21

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Re: Pressure difference between kegs
« Reply #12 on: October 30, 2013, 02:17:06 PM »
It seems to be flowing at a higher rate, not just foamy (pouring at the higher rate causes more head in the glass though). I guess if a blockage is causing it to foam, it could be seen as a higher rate at the tap. Gmac, your suggestions sounds like a good idea. I'll try it tonight and see what I can find out. Would it make sense that a blockage is actually causing the slower of the two pours, as opposed to the faster?