[rbowers]

I just started kegging and my first beer on tap seems to have an inordinate amount of head (I'm pouring half beer, half foam).  I had the keg force carbonate at about 17 psi for several days at around 50 degrees.  After that time should the pressure be reduced to a certain pour pressure?  Will the beer stay carbonated if I drop the pressure to say 6-10?  I am planning on dropping the temp for my lager (same fridge as tapped beer)- what should I do regarding the pressure setting once it's at a much lower temp, say 36 degrees.

[Slowbrew]

There are several factors involved here.  I'm no expert but the basics might help you out a bit.

How is your beer line?  Most people say you will drop 2psi for every 1 foot of line and you want that to be balanced with the serving pressure.  So, at 17psi you in theory need between 7 and 8 foot of line.  You can drop the serving pressure and see if that helps.  If you go too low you may end up without any head but then you can adjust it back up a bit at a time until it is where you like it.

Others will give you lots more info but this can get you started.

Paul

[mabrungard]

For the conditions you stated, 50F and 17 psi.  It appears you're looking for about 2.5 volumes of CO2 in your beer.  If the temperature is going to be dropped to 36F, then you can reduce the pressure to about 11 psi and still maintain the same carbonation level. 

[rbowers]

I guess my question is: once the beer is carbonated at the force carbonation pressure does reducing the pressure to say 7-10 psi result in any co2 coming out of solution?  Does it make any sense to say the beer tastes under carbonated but there is copious amounts of head?  Beer line is about 4-5 ft.

[dolecek21]

I've only been kegging for the last few batches, so I am still trying to dial this in as well.  Approximately what pressure are you looking for at the tap?  I ask because my tap lines are approx. 4 1/2 feet and setting the pressure to 10 psi results in too much pressure/head at the tap.  It seems that for a decent pour I had to decrease the pressure to 4-5 psi.  From what I've read it seems as though I should be able to set the pressure higher than this.

[dolecek21]

I guess my question is: once the beer is carbonated at the force carbonation pressure does reducing the pressure to say 7-10 psi result in any co2 coming out of solution?  Does it make any sense to say the beer tastes under carbonated but there is copious amounts of head?  Beer line is about 4-5 ft.

I have had the same issue with the beer tasting under carbonated, but I figured it was because a large amount of the CO2 is being forced out in the pour.  If I closed the valve at the regulator, released most of the pressure in the keg, and poured the carbonation level seems more appropriate. 

[rbowers]

I'm gonna try releasing all the co2 off for a few seconds and then retry at a pressure of 4-6 psi.  Keep u posted

[Joe Sr.]

If you're pouring too fast and getting too much foam, you're pushing the CO2 out of suspension and the beer will taste undercarbonated.

You can bleed off pressure to get a good pour, but be aware that (assuming you do not have the keg hooked to gas) it will reach a new equilibrium - the CO2 will come out of the beer until the head pressure in the keg is balanced.

[liquidbrewing]

I guess my question is: once the beer is carbonated at the force carbonation pressure does reducing the pressure to say 7-10 psi result in any co2 coming out of solution?  Does it make any sense to say the beer tastes under carbonated but there is copious amounts of head?  Beer line is about 4-5 ft.

  Yes, if you force carb at 17 psi and then set to 7 for a few days, it will de carbonate.  But temperature plays a big factor too.  This sounds like it could be your issue.   Having a nice cold fridge is key.  I use 5 ft / 3/16" ID beer line, fridge is about 38 degrees and I serve at 10 psi.  No problems really, the first pour is always an issue, since the Perlicks I use keep beer at room temp basically.  But after that no problem.

  Does it just taste undercarbed?  How does it look?  Find a tall skinny glass and pour a beer.  Hold it up to the light and examine your "bubbles".  Maybe compare with another of your beers, or a commercial example that you've always thought had good carbonation.
 
   Another factor could be your grain bill.  Using a lot of dextrine, crystal, or other adjuncts could significantly increase the head.  A guy in our local club made a Rye IPA, fantastic beer but every pour was about a half beer/half foam for a while.  I think he resolved it by lowering the psi and letting it equalize to a lower pressure.

[Joe Sr.]

 Yes, if you force carb at 17 psi and then set to 7 for a few days, it will de carbonate.  

Yes, but it will only de-carbonate if you release the 17 psi head pressure down to 7, either by pouring beer or releasing the PRV.

[rbowers]

So I have lengthened the hose to 7 ft but still a lot of foam.  I've turned the pressure off and I am just letting off some of the gas every hour or to see if that helps.  Is it just difficult to dispense beer at higher temps because to keep it carbonated you have to have these high psi levels of 17 or so?  I am letting my lager warm up to get rid of some diacetyl but dropping the temp back down to lager temps over the next few days.  I'll have to wait and see how hints pan out.

[liquidbrewing]

 Yes, if you force carb at 17 psi and then set to 7 for a few days, it will de carbonate.  

Yes, but it will only de-carbonate if you release the 17 psi head pressure down to 7, either by pouring beer or releasing the PRV.

I have to disagree.  In my experience when I force carb I set to 30 for two days, I don't vent, I just dial it down to ten for another five days.  The beer is not carbed to 30 it's carbed to roughly 10.  No matter if he vents, the beer is still carbed to 17 until he leaves it on the gas at a lower pressure to equalize.  Now if he vents, shakes the keg vents again, so on and so forth, then he can de carbonate much quicker.  However I don't recommend this method, I tried it and ended up with beer everywhere!

What temp are you serving at?  Find a pressure to temperature chart for amount of Co2 volumes you want.  That should help.

Try this one:  http://ebrew.com/primarynews/ct_carbonation_chart.htm

[HydraulicSammich]

rebowers
Welcome to kegging!  It can be very frustrating but eventually, most satisfying.  I have been through the problems of over carbing, leak detection and whatever.  I have six beers serving at all times.  Each has psi regulation.  I have found that most all of my beers are between 11 and 13 psi.  I have at least 10 feet of line for a nice slow pour with minimal head unless you want to final fill from vertical.  I have found, carbing at this pressure for 5 to 7 days at 38 to 42 degrees is perfect for me.  It is also the serving pressure with the length of line.  Good luck!

[Joe Sr.]

I have to disagree.  In my experience when I force carb I set to 30 for two days, I don't vent, I just dial it down to ten for another five days.  The beer is not carbed to 30 it's carbed to roughly 10.  No matter if he vents, the beer is still carbed to 17 until he leaves it on the gas at a lower pressure to equalize.  

If he's already carbonated to 17psi, turning down the regulator will have no impact.  Where would the extra pressure go?  It does not go back into the CO2 tank.

I'm sure you already know this, but when you vent the pressure, you're releasing the head pressure.  Once the vent is closed, CO2 then comes out of solution to balance the pressure in the keg, thus reducing the carbonation of the beer.  To have a significant impact, you would need to do this several times over the period of a day or two, but it certainly will reduce the carbonation of the beer.

In your case, after two days at 30 psi you're likely not fully carbonated and turning down the regulator to the pressure you want works.  Your two days at 30 are simply speeding the process.  In those first two days, your beer wouldn't be overcarbonated if you tried to pour it.

Since he's already overcarbonated, he's got to get pressure out (venting), not just reduce the pressure going in.

[rbowers]

This brings up some points I could use clarified re: ball lock kegs and co2 in general.  If I were to carbonate at 30 psi for 2 days I assume once the co2 has dissolved the co2 tank continues to push a pressure of 30 psi onto the beer unless reduced.  If you do reduce the pressure prior to purging the valve or pouring a beer does the head space pressure drop to the new setting or does it remain at 30 psi?  Will the co2 tank only actually put more gas into the keg once the pressure drops at or below the new co 2 pressure setting?  Does the excess foam come more from too much carbonation suspended in the beer, too high a head space pressure, or some combination- or are these in the end the exact same thing?  I should have paid more attention in physics class I guess.