Is it possible to overcarb a keg at 10 PSI

[william_shakes_beer]

I have had a hefewizen keg in the on deck position at 12 PSI for about 5 months. Tapped it the other day and was rewarded with a full glass of foam. I pulled the PRV, removed the co2 line and have been serving glasses of foam ever since. Its getting better, but I never dreamed it as possible to overcarb at serving pressure. I thought after it reached equilibrium it would sit there quietly util I was ready to start serving.

 

[LeeH]

It must have been fermenting still, you cannot over carbonate if you have controlled the variables.

 

[Vale71]

A standard CO2 regulator has a check valve so it will not act as a spunding valve if your beer's carbonation where to increase due for example to it becoming infected in the 5 months it's been in storage. Do you have a manometer and can you check the actual equilibrium pressure after having had the CO2 line disconnected for a couple of days? You might find out that your beer is not actually carbonated to 12 PSI.

 

[william_shakes_beer]

I do not have a pressure gage I can use to check the actual keg pressure. The keg tastes delicious, so its not infected.

I usually ferment for 4 weeks before kegging, and I have never had a batch fail to ferment completely. I ferment in a freezer with a heat source and dual stage temp control. My kegerator has 2 slots serving and a third gas outlet for conditioning.

My usual packaging procedure is to fill the keg with fermented beer, pressurize and set the keg aside at a stable temp in the basement until I have a empty slot in the kegerator. I place the keg in the kegerator, plug it into serving pressure and let it sit to carb until I kick a keg ( usually several months) Then I plug in to a tap and pour away.

This particular keg I unplugged the gas completely and am serving solely from the internal pressure of the keg. Good lacing and abundant co2 bubbles on the inside of the glass.

If fermentation was completed in the sealed keg, wouldn't the yeast die when the pressure reached a certain level?

 

[Vale71]

If fermentation was completed in the sealed keg, wouldn't the yeast die when the pressure reached a certain level?

Yes, at over 30 bar of pressure but your keg would have exploded much sooner.
Either you have an infection or fermentation was stalled and resumed slowly in the keg or your keg is not really overcabed (hard to really tell without a manometer) and your issue is only with serving.

 

[Gnomebrewer]

Are you sure the issue's from overcarbonation?
Could the foaming be from something like a bad o-ring on the liquid post?
Or a loose hose connection to disconnect?
Or line length too short (12psi at around freezing temperatures is 2.7 to 2.8 volumes - which is effectively overcarbonation if your system is setup for a more 'normal' 2.2 to 2.4 volumes).

 

[william_shakes_beer]

If I were *sure* I would not be asking the question
What I am sure of is the facts I presented in the OP. I am speculating that its over carbed, because it exhibits all the symptoms and I have not made any changes since the last dozen or so kegs I have dispensed from that tap. ( no conditions I can see that would introduce a leak, for instance)

Two additional factoids which may or may not be relevant: the first couple glasses after I cleared the lines had a large amount of sediment in them. I presume from trub in the bottom of either the old or the new keg. That has now cleared and the product is bright and sparkling. Last weekend I pulled out the empty keg, which had frozen itself to the freezer bottom. Chipped out the accumulated ice and readied for the next keg that's going in ( pumpkin ale, packaging next weekend and directly into the keezer for October serving)

 

[Cavpilot2000]

I'll echo that no, you can't overcarb at 10 PSI.

Here are the only possible causes:
1: stalled/restarted fermentation in serving keg
2: Infection
3: Failed pressure gauge (maybe you were pushing way more than the 10 PSI it was indicating)
4: Other equipment failure - again, a failed post or dip tube o-ring can result in pushing lots of foam. Before you automatically dismiss it, they don't last forever - maybe it went bad since the last keg. Other options: dirty serving line (nucleation sites inside the tubing), ...
5: The laws of physics don't work correctly in your serving setup, allowing overcarbing at 10 PSI.

 

[bkboiler]

Serving line length? Type?

 

[william_shakes_beer]

Serving line length? Type?

15 feet of 3/16" bev tubing

 

[william_shakes_beer]

update: the keg is now behaving itself. I have completely drained the head pressure and reattached the co2 bottle. The best explanation I can support is stalled fermentation that resumed in the keg.