Need to Carb 4 kegs...Kegerator only holds 2!

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LongDukDong

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I've been reading about carbing at room temp so i wanted to run an idea by you folks to see if it's doable or if there are any other tips or recommendations.

I'm having a little shindig in a couple weeks and would like to have 4 taps going but as i pointed out my kegerator only holds 2 kegs. Would it be a good idea to carb the 2 kegs in the fridge @ 15psi for a week, disconnect and carb the other 2 at room temp for a week at 35psi. Chill the room temp kegs the morning of the shindig in water & ice, release pressure and connect all 4 kegs at 12-15psi for serving?

I'm using picnic taps with 5' of hose and get mixed results on pours for whatever reason between pin and ball lock but nothing too bad.

Sound good to you folks?

Thanks in Advance!
 
Why not carb the two in the fridge til carbed appropriately. Then remove and put the other two in the fridge so they cool over night than carb those appropriately. That way you have all 4 kegs carbed correctly and all you need to do before serving is chill them.

Only down side is you don;t have anything on tap to drink during that time.
 
I would put the first two on at 30 PSI until they are chilled, then give them a good shake to get more CO2 into solution, then set at your desired pressure and leave for the rest of a total time of 1.5 weeks. Take those two out, then do the same with the other two kegs.

That should get your 4 relatively evenly carbed kegs if you can get them all chilled the same. It'll probably take a couple of days for the warmed up kegs to get all that CO2 back into solution, so you may want to figure out how you can start chilling the kegs a couple days in advance. You can always use the shake method to get more CO2 into solution once they are chilled.
 
brrman said:
Why not carb the two in the fridge til carbed appropriately. Then remove and put the other two in the fridge so they cool over night than carb those appropriately. That way you have all 4 kegs carbed correctly and all you need to do before serving is chill them.

Only down side is you don;t have anything on tap to drink during that time.
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Because it takes 2 weeks for the simple method and he only has two weeks total. He would need 4 for this method.
 
If it matters, I have a Brown Porter, Imperial IPA, Belgian Blonde and an APA. i figure the Porter and IPA can have a lower carb level than the Blonde and APA.

As for the recommendations, if i force carb at 30psi then shake, chill for a day, release pressure and adjust to 10-12psi for a 4-5 days, swap them out and do the same with the other kegs....Would the first rotation of kegs still be farely carbonated after sitting at room temp for a few days? I could have all 4 kegs carbed at 1 time but as you know only 2 can be chilled. I know....time for a keezer!
 
LongDukDong said:
As for the recommendations, if i force carb at 30psi then shake, chill for a day, release pressure and adjust to 10-12psi for a 4-5 days, swap them out and do the same with the other kegs....
Click to expand...
If you use the pressure / temperature chart, you won't have to shake. They will be ready to chill, hook up at serving pressure and pour. The CO2 in solution will be fine.



Edit:
This link goes to higher temperatures and may be more useful.
 
AnOldUR said:
If you use the pressure / temperature chart, you won't have to shake. They will be ready to chill, hook up at serving pressure and pour. The CO2 in solution will be fine.

I see what you're saying, but wouldnt that take 2 regulators so i could carb the kegs at room and cooled temps? Or are you saying, no need for the shaking, just add 30psi to room temp kegs disconnect and let the 2 in the fridge sit at 10-12psi connected until they are ready to serve?

If so, i'm guessing i would periodically have to hit the room temp kegs at 30psi as the co2 is absorbed by the beer.
Click to expand...
 
Here's my method:

Start with room temp kegs.

Put kegs into fridge, (mine is 37F). Hook up to 34 PSI CO2. Let sit for 48-60 hrs. Vent kegs, drop pressure to 11-12 PSI, sample.

60 hrs usually is very well carbed. 48 hours is usually slightly under.

I've yet to overcarb with this method, (except when I forgot about the kegs for a week!). I have overcarbed MANY times by shaking. Never shake, is my opinion.

Here's what I'd do if I were you. Put 2 warm kegs in the fridge, 30 PSI for 48 hrs. Drop to serving pressure, sample. If it's not carbed enough, give it 30 PSI for another 6-12 hrs, sample again. Then, swap kegs and repeat.

Shaking is for rattles.
 
LongDukDong - Yes, you would periodically have to hit them with some pressure to make sure they carb all the way up.

shortyjacobs - once he takes those kegs out of the fridge, CO2 will come out of solution, so his kegs will be undercarbed. He could use your method, but then when he takes them out of the fridge, put them at a "storing" pressure that would keep them carbed the same and then vent when he wants to serve and use his serving pressure. But AnOldUR's method would be easier, IMHO
 
SeanT said:
LongDukDong - Yes, you would periodically have to hit them with some pressure to make sure they carb all the way up.

shortyjacobs - once he takes those kegs out of the fridge, CO2 will come out of solution, so his kegs will be undercarbed. He could use your method, but then when he takes them out of the fridge, put them at a "storing" pressure that would keep them carbed the same and then vent when he wants to serve and use his serving pressure. But AnOldUR's method would be easier, IMHO
Click to expand...

Nope.

If they are carbed to an equilibrium pressure of, say, 12 PSI in the fridge at 38°F, then when he takes them out, they will warm up. As they warm up, the pressure inside of them will rise up to 25-30 PSI, the equilibrium pressure at that temp. However, CO2 is still all in solution. The pressure just follows the equilibrium line as temperature changes. When he puts them back into the fridge, they will cool down, and the pressure will drop back to 12 PSI.

I do this ALL the time. I carb up kegs, then put them in my basement. When ready to drink, I throw them in the fridge over night, (WITHOUT gas connected), so they can return to fridge temp. Then, I connect gas at 11-12 PSI and drink. They are still perfectly carbed.

A keg is a big bottle. Think about it, bottles don't "lose carbonation" when they warm. The CO2 you put in is the CO2 that's in there, regardless of temp. As long as the keg stays sealed, it will hold carbonation, regardless of temperature, indefinitely.

(Edit, again, to clarify, all CO2 will remain in solution as long as the keg remains sealed, no matter what the temp. The trick is, you have to cool the keg back down before connecting it to 12 PSI. If you don't, you WILL lose some carbonation as it cools down because you drop the pressure in the headspace.)
 
Why not naturally carb all four??? or 2?

I have a kegerator and two taps with only room for two kegs. I naturally carb all my kegs so they are ready to go overnight if I run out the day before.

-Quite necessary... Gota lot of mooch friends.

- Oh, and I have yet to have a first pour with yeast in it... Strange but true..
 
shortyjacobs said:
Nope.

If they are carbed to an equilibrium pressure of, say, 12 PSI in the fridge at 38°F, then when he takes them out, they will warm up. As they warm up, the pressure inside of them will rise up to 25-30 PSI, the equilibrium pressure at that temp. However, CO2 is still all in solution. The pressure just follows the equilibrium line as temperature changes. When he puts them back into the fridge, they will cool down, and the pressure will drop back to 12 PSI.

I do this ALL the time. I carb up kegs, then put them in my basement. When ready to drink, I throw them in the fridge over night, (WITHOUT gas connected), so they can return to fridge temp. Then, I connect gas at 11-12 PSI and drink. They are still perfectly carbed.

A keg is a big bottle. Think about it, bottles don't "lose carbonation" when they warm. The CO2 you put in is the CO2 that's in there, regardless of temp. As long as the keg stays sealed, it will hold carbonation, regardless of temperature, indefinitely.

(Edit, again, to clarify, all CO2 will remain in solution as long as the keg remains sealed, no matter what the temp. The trick is, you have to cool the keg back down before connecting it to 12 PSI. If you don't, you WILL lose some carbonation as it cools down because you drop the pressure in the headspace.)
Click to expand...

I still disagree. Using more numbers, assume he wants 2.6 volumes at 38F. This requires ~12 psi at 38F. If he then warms the keg up to room temperature (70F), the pressure in the headspace of the keg is 13.1 psi (from the ideal gas law, p2 = p1 *T2/T1). The chart tells us that to keep 2.5 volumes of CO2 in solution , he needs 30.4 psi. So, it seems there is a driving force for the CO2 to go out of solution.

How long those it takes for the CO2 to come out of solution, I don't know. Or how easy it is to tell its has lost "that much" (I'm not sure if that would be a lot or little of carbonation that is lost). As for the bottle issue, I don't see why CO2 can't come out of solution. I also don't buy beer that is warm when I buy it, and it goes in my fridge as soon as I get home.

I'm not sure why we can't lose carbonation due to time/temperature if we can force carbonation in.

Let me know if there is a flaw in my logic.
 
SeanT said:
I still disagree. Using more numbers, assume he wants 2.6 volumes at 38F. This requires ~12 psi at 38F. If he then warms the keg up to room temperature (70F), the pressure in the headspace of the keg is 13.1 psi (from the ideal gas law, p2 = p1 *T2/T1). The chart tells us that to keep 2.5 volumes of CO2 in solution , he needs 30.4 psi. So, it seems there is a driving force for the CO2 to go out of solution.

How long those it takes for the CO2 to come out of solution, I don't know. Or how easy it is to tell its has lost "that much" (I'm not sure if that would be a lot or little of carbonation that is lost). As for the bottle issue, I don't see why CO2 can't come out of solution. I also don't buy beer that is warm when I buy it, and it goes in my fridge as soon as I get home.

I'm not sure why we can't lose carbonation due to time/temperature if we can force carbonation in.

Let me know if there is a flaw in my logic.
Click to expand...

You're right. I should have said "almost".

Carbonation will drop from 2.6 to 2.54 volumes in the beer. I suppose if you want to be a stickler about it, you need to hit it with pressure after it hits room temp, (so remove kegs, wait a day, blast with 30 PSI). In practice, I don't worry about 0.06 volumes of CO2.


Fridge

12 psi
2.6 volumes
5 gallons beer
0.25 gallons headspace
13 gallons STP CO2 in beer
38 F
3.3 C



Room Temp

68 F
20 C
30.4 PSI
2.07E-04 expansion coefficient
5.0207 gallons beer
0.2293 gallons headspace
1.638405797 pressure increase due to temp
1.083296991 pressure increase due to beer expansion
15.67829721 remaining pressure differential
0.075930894 moles in headspace
0.120965623 moles needed for 30.4 PSI at 68F
0.04503473 difference in moles
1.008777941 liters at STP
0.266168322 gallons at STP
12.73383168 new gallons STP CO2 left in beer
2.536266194 new volumes of CO2 in beer
 
shortyjacobs said:
You're right. I should have said "almost".

Carbonation will drop from 2.6 to 2.54 volumes in the beer. I suppose if you want to be a stickler about it, you need to hit it with pressure after it hits room temp, (so remove kegs, wait a day, blast with 30 PSI). In practice, I don't worry about 0.06 volumes of CO2.
Click to expand...

I agree, if anyone can detect the difference between 2.6 and 2.54 volumes of CO2 in a beer, they are probably superhuman.

Not trying to be an *ss (or say you're wrong), but where did your numbers come from? If the response would take too much time to write, no worries, I don't want to make you write a book. But if you have a link/spreadsheet/reference I'd like to learn more. Thanks
 
SeanT said:
I agree, if anyone can detect the difference between 2.6 and 2.54 volumes of CO2 in a beer, they are probably superhuman.

Not trying to be an *ss (or say you're wrong), but where did your numbers come from? If the response would take too much time to write, no worries, I don't want to make you write a book. But if you have a link/spreadsheet/reference I'd like to learn more. Thanks
Click to expand...

Not an ass at all. I whipped it out real quick at work in excel, and there may be mistakes, (I fixed a few before posting, originally I had it dropping to 2.33 volumes until I realized one of my pressure calcs was done with gauge pressures, not absolutes). I just got home, and have to run out again, but wanted to post to say that later tonight, when I finally get back home, I'll post it up.....I realized it was dumb for me to not truly "show my work", but I had to run at the time, so I just did a quick copy-paste....hence why I came back expressly now to say "but wait, there's more!". Once I get my work comp booted up tonight after baby classes, we can see if I'm really right or not.
 
DustinHickey said:
Why not naturally carb all four??? or 2?

I have a kegerator and two taps with only room for two kegs. I naturally carb all my kegs so they are ready to go overnight if I run out the day before.

-Quite necessary... Gota lot of mooch friends.

- Oh, and I have yet to have a first pour with yeast in it... Strange but true..
Click to expand...

This is what I do as well. I'd stick 2 in the kegerator at the desired psi for 2 weeks and add the appropriate amt. of corn sugar to the other 2 at room temp for 2 weeks. Much less of a hassle this way.
 
shortyjacobs said:
Not an ass at all. I whipped it out real quick at work in excel, and there may be mistakes, (I fixed a few before posting, originally I had it dropping to 2.33 volumes until I realized one of my pressure calcs was done with gauge pressures, not absolutes). I just got home, and have to run out again, but wanted to post to say that later tonight, when I finally get back home, I'll post it up.....I realized it was dumb for me to not truly "show my work", but I had to run at the time, so I just did a quick copy-paste....hence why I came back expressly now to say "but wait, there's more!". Once I get my work comp booted up tonight after baby classes, we can see if I'm really right or not.
Click to expand...

Thanks, sounds good. I understand quick and dirty, I made more assumptions than you did (no thermal or volume expansion, incompressible/ideal gas, etc).
 
LongDukDong said:
I see what you're saying, but wouldnt that take 2 regulators so i could carb the kegs at room and cooled temps?
Click to expand...
Yeah, it would take a primary and secondary regulator on your tank (or a back-up CO2 tank) which I'm now guessing you don't have. If that's the case shortyjacobs plan is the next best thing. I use that same method when I need to carb and don't have time for the "set-it-and-forget-it" approach. And like he says, once they're carbed they'll stay that way even after you pull them out of the fridge to put the other two in. As the kegs warm, the pressure in the head space will increase as a small amount of CO2 come out of suspension to equalize the system, but the CO2 in suspension stays relatively constant.


Edit:
And the less head space you leave in the keg the better!



Me like this . . . :mug:
shortyjacobs said:
Shaking is for rattles.
Click to expand...
 
OK, here's the spreadsheet. I commented it all out. A few notes:

1) I was off slightly on a few calcs....actual end result is 2.55 volumes after warming, so you lose 0.05 volumes of carbonation. 0.05 volumes is well within the error of your regulator gauge, so it should be not noticible

2) I am assuming a final pressure of 30.4 PSI still, which is really the pressure for 2.6 volumes of carbonation in the keg. Really, as CO2 comes out of beer solution to fill the headspace, the pressure will stabilize at a slightly lower value, (somewhere between the value for 2.55 volumes of carb and 2.6 volumes of carb). I could have set my spreadsheet up to solve the simultaneous equations to get an EXACT level of carbonation, but really what this means is that 2.55 final volumes of carbonation is the LOW estimate, and that the actual value would be slightly higher, (closer to 2.6...probably 2.56ish).

3)All calculations are done using PV=nRT, so incompressible/ideal gas, (which CO2 is pretty damn close to under these conditions). Volumetric expansion is assumed to be linear over this temperature range, (it isn't, but the error level is VERY low). Gauge pressures assumed taken at sea level, (again, this won't change much of anything, unless you are at the top of Mt. Everest). Absolute temperatures done with 0°C = 273K, simply because I was too lazy to type in 273.15K. Order of changes as keg warms is isochoric pressure change as headspace warms, isothermal pressure change as beer expands, then finally CO2 coming out of solution to hit equilibrium partial CO2 pressure.

http://www.slingfile.com/dl/oiadc/beercarbonation.xls.html

Edit: To be truly scientific about this, I should use sig figs. Since I started with 2.6 volumes as my base assumption, and got 2.55 as my end assumption, I need to set 2.55 to 2 sig figs. The round to even rule means my answer is 2.6 volumes with sig figs....therefore the beer actually loses no carbonation by a twist of logic :D
 
shortyjacobs said:
OK, here's the spreadsheet. I commented it all out. A few notes:

1) I was off slightly on a few calcs....actual end result is 2.55 volumes after warming, so you lose 0.05 volumes of carbonation. 0.05 volumes is well within the error of your regulator gauge, so it should be not noticible
...
Click to expand...

Sounds good, thanks for the file. I was just using gauge pressures, not absolute. Thanks for helping me understand.
 

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