Keg Force Carbing Methods Illustrated

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Bobby_M

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Yes, you can shake at chart pressure forever and it won't overcarb but it's a little impractical because you have to sit there and do it for a while, or come back to it regularly. I really have no idea how many times you'd have to do it for or how much time it shaves, but rigging it into a huge paint shaker would be awesome.
 

fdb16

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FYI: i set it to 11 psi and just rocked for about 30 min with my feet while watching football on the couch. I got tired and let it sit for awhile, went back at it an hour later for about 40 min. Decided enough was enough and let it sit in the kegerator. I just took a pull about 1 hr after rocking to see where I am at, and all looks good. Well carbed, probably not to perfection, but well enough. My plan was to rock until the beer stopped taking on gas, that never happened. Next item to brewery list, supersized paint shaker! (better plan on better timing)
 

Frodo

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Sounds like a good upper body workout too!
 

BrokenDog

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I will be kegging my first beer in the next week or two and want to have this page for reference, thanks.
 

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Bobby,
quick question for you:

when force carbing, we're concerned the liquids ability to absorb CO2 at given temps. why do the same parameters not apply when naturally carbing a bottle or even a corny?

When I look at naturally carbing charts, there's no compensation for varying temps.

Thought of that the other day and couldn't come up with an answer.

Thanks :mug:
 
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Great question. The answer seems obvious to me but I'm having a hard time writing it out but here's a go at it.

When sugar priming or naturally carbing, you're adding a fixed amount of additional CO2 (potential) to a sealed vessel. The amount of CO2 the sugar/yeast produces is an additive effect there. If you start with 1.2 volumes and the sugar will add 1.7 volumes, you have 2.9 volumes total. You really can't change it once you put the cap on.

When you force carb with CO2, you're achieving total carbonation by a fixed pressure at a certain temp. If you set the pressure (based on the charts) to get to 2.5 volumes, it doesn't matter if you start at .9 volumes, or 1.3 volumes, or 2.4 volumes. It will always seek equilibrium at 2.5 volumes. The only thing that changes is how long it takes to get there.

Does that make sense?
 

Hugh_Jass

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I'm still trying to wrap my Hugh_Jass head around this. :D

When you force carb with CO2, you're achieving total carbonation by a fixed pressure at a certain temp. If you set the pressure (based on the charts) to get to 2.5 volumes, it doesn't matter if you start at .9 volumes, or 1.3 volumes, or 2.4 volumes. It will always seek equilibrium at 2.5 volumes. The only thing that changes is how long it takes to get there.
so when force carbing, the CO2 dissolving into solution is dependent on pressure/temperature. The lower the temp, the less psi required to force the same volume of CO2 into the beer. I understand this.

When priming w/a certain amount of sugar, the amount of CO2 given off by adding a certain amount is sugar is known, and that CO2 will be all be contained within the container. This CO2 dissolved into the solution will be the same regardless of temp?

I'm still scratching my head a bit. More later. Thanks
 

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I'm still trying to wrap my Hugh_Jass head around this. :D



so when force carbing, the CO2 dissolving into solution is dependent on pressure/temperature. The lower the temp, the less psi required to force the same volume of CO2 into the beer. I understand this.

When priming w/a certain amount of sugar, the amount of CO2 given off by adding a certain amount is sugar is known, and that CO2 will be all be contained within the container. This CO2 dissolved into the solution will be the same regardless of temp?

I'm still scratching my head a bit. More later. Thanks
It has nowhere to go and once the head space is full, it will force itself into the beer regardless of temperature since the yeast will consume the sugar and produce CO2. Unless of course you have a loose cap.
 
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The added carbonation that happens from adding sugar back into the beer is pretty predictable based on how fermentable that sugar is. The only way you'd counteract its natural trajectory is to chill the bottle before it was done.

There was a whole debate on another thread about how the CO2 dissolves into the beer during bottle conditioning and the consensus is that the pressure of dissolved CO2 and the headspace pressure is pretty much at equilibrium at any given time, all the way up full carbonation. In other words, the headspace doesn't "get full" of CO2 and then dissolve in a stringent order like that.

The reason why the volumes of CO2, which is our measure of carbonation level, is fixed no matter what temp the bottle is at is because it's a closed system. The pressure increases as temperature does, but the number of CO2 molecules never changes.
 

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I had to look some of this up, AND I've been taking a couple pulls off my first kegged beer! (so the point is, don't take this as gospel since I'm kinda drunk). I'm just so excited to have pulled a couple beautiful pints that I feel I need to add something, whether it's good or not...

First off:

Volumes of CO2 = 1 Liter of CO2 gas per 1 Liter of Beer at STP.

STP is "Standard Temperature and Pressure". Standard Temperature is 0C (32F) and Standard Pressure is 1 atmosphere (14.7 psi aka the weight of earth's atmosphere at sea level). (I didn't realize I always had 14.7 psi pushing down on every inch of my head BTW... no wonder I can't fly, I'm pretty sure my head is more than 5" x 6", or 30 square inches... so I have 441 lbs pushing down on my head!!! Holy crap I'm surprised my neck doesn't snap). Anywho, back to the task at hand:

The only variables we're working with, given a particular volume of CO2 as chosen by style if you so desire, are Temperature and Pressure.

So in a bottle with carbonating sugar and a sealed cap, if the yeast do their job they slowly create CO2 over the course of a week or 3, and they make the corn sugar you added at bottling time into ethanol and CO2. In other words there will be a steady BUILDUP OF PRESSURE while the sugar is converted. So the reason a natural carb chart is important for bottling is that you need to know precisely how much CO2 is already dissolved (created during fermentation) and how much additional you'll need to add during bottling. That's why the temp/carb charts are so important for bottle carbing.

With kegging, you apply a constant pressure from the CO2 canister through the regulator. It's not a closed system. The temp makes a difference now, not in determining whether the yeast will ferment the sugar but in how much CO2 will dissolve under the CONSTANT PRESSURE you're applying. That's where the chart comes in to tell you how many volumes CO2 will be absorbed under a given pressure of CO2.
 

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I haven't read more than 7 pages so far, but man is this a great, informative thread! Thanks Bobby! I'm considering converting fridge and this thread, in only 7 pages, answered the questions I had thus far.
 

johnnyk

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I've been looking everywhere for something like this. Great explanation.

I have my cornies, CO2 gas etc and i'm going to put my beer in my keg tonight and kept coming across so many different ways to carbonate the beer I was getting confused!

This is great and I will hopefully be able to do it easy enough now.

Cheers,
 

Jknapp

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Any adjustments to make to the process if kegging in 3 gal cornies?

I'm thinking the smaller keg affects the headspace to beer ratio.
 

proudportland

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I am new to kegging and was wondering what you mean when you say 2 vol.co2. Also should I be force carving inside or outside the kegorator? Thank you for reading. brew on my friends brew on
 

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Well First off as a n00b to home brewing and kegging (I have been planning out all my first-time purchases for about the last 1-2 weeks, and have found this site to be a sanity saver) I'd like to thank Bobby and all the other experienced folks here for trying to keep this as understandable as possible while still trying to illustrate the important points. My plan is to jump kind of head first into this new planned hobby and tackle both brewing and kegging my first time out as my SWMBO does not want to have to deal with all the bottles. I was very intimidated by the thought of kegging my own beer, but after making it thru all 30 pages I am much more confident. Thank you all again, I'm sure I will have some questions once it comes time to actually tackle the task ahead of me as I still need to order all my supplies, but this thread alone proves to me that I have nothing to worry about as you are all so helpful. I cant wait to start and I'll keep everyone posted on how the Virgin batch comes along...till then Cheers!
 

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I'm brand new, and I majored in History & English. So, I have trouble understanding volumes to PSI. I get the concept of beer absorbing CO2 to create carbonation (head), and I get that it happens naturally over time.

One of my (many) problems is that I use a 2nd hand Bev Air that I got for a steal. I installed a double tower and have had 2 commercials 1/6 or 1/4 on tap for about a year - at about 10-12 PSI. Now that I've added a batch of homebrew (german ale), I'm having trouble figuring out how to strike an even PSI keel so all the kegs get along in there.

Should I just set it at 8 PSI and forget it?
 

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... post that was being responded to was deleted...
 

dstebor

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Thanks for this post very informative, i'm planning on putting my barleywine in keg tomorrow after two weeks dry hopping in secondary.
 

bctdi

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ok...great info here....I wonder if we could take it a step further...assuming a 2 week time frame using the set/forget method / force carb chart can we do a little math to come up with a force carb time chart for a given "boost carb" pressure of 40 psi?...for example at 40 deg. f according to the set/forget chart for 2.39 volumes and 11 psi we can multiply 11(psi) x 14(days)=154 (psi)....then divide 154 x 40(psi)= 3.85 (days to reach 2.39 volumes @ 40 psi).....then divide 2.39 (volumes) by 3.85 (days) = .621...........this gives us our volumes per day of .621 at 40 psi....from this we can just multiply .621 by a given number of days to see how many volumes we will be at for a given temperature

Ok after Bobby M. pointed out that the carbonation is not linear I decided to edit this post and remove my numbers because I think they will lead to overcarbing. It would be nice to have a time chart , but not at the expense of the beer.
 
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The numbers may work in practice, but not because the method of calculation was logical ;-)
The rate of absorption is not linear at all. It starts faster due to the pressure delta between headspace and beer and slows as it gets closer to equilibrium. If someone is smart enough, I think calculus would be involved. I am not that guy.
 

bctdi

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Ok so the rate of absorption is directly proportional to the differential pressure.....that makes sense....I think the numbers kind of work possibly because when burst carbing you will always have a high differential since you're using 40 psi on a beer that only needs 10 psi at equilibrium , and you're stopping long before you reach a low differential. My numbers were only meant to be a ballpark measurement way to get close to your carb level quickly without going over based on temp and how many volumes you wanted to get to.Most beers are good at 2.4 volumes, but I just did a belgian tripel to 3 volumes using those numbers and it seemed to work pretty well. Unfortunately I can't back anything up with hard data .....just my own experience and all the info I could gather from threads like this one.I'm not the calculus guy either:D
 

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When you shake the keg, do you leave it connected to the CO2 tank at the given pressure, or do you disconnect it?
ezziey

edit: So, when we carb our beer, we put a certain volume of CO2 in it per volume of liquid, correct? So based on that, depending on how much beer you are carbing, we can calculate how much CO2 we need for a given carbonation level. Here's what I propose: can't we estimate the amount of headspace in our kegs (the volume) and using that, estimate what pressure we need to apply to the headspace in order to accomplish the aforementioned volume of CO2? Further, couldn't we attach a pressure gauge to our CO2-in port to gauge (no pun intended) when our CO2 has finished dissolving into the beer? I know there's a guy that hooked up a pressure gauge to a bottle to observe the carbonation of beer over time with natural carbing, but I'm betting we can get pretty damn scientific with this force carbing thing and take the guesswork completely out of it. I'm going to do some searching/research and see if I can come up with some numbers, but I thought I'd post this here in case this has already been proposed or talked to death.
 

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I always keep the co2 connected to the keg while shaking because if you listen closely it will continue to push co2 into the keg. I leave it at the high pressure and connected for 1 day in the fridge while it gets cold. Then I put the pressure back down to 12 or so and let it sit for 3 to 4 more days. That seems to work well for my system.
 

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I just pulled my first two beers from my new keezer. I used Bobby's method here of tripling the serving pressure for 24 hours then purging and resetting at serving pressure for a week. Turned out PERFECT! Thanks Bobby for a great thread!
 

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When you shake the keg, do you leave it connected to the CO2 tank at the given pressure, or do you disconnect it?
ezziey
Yes leave it connected. You want that pressure of CO2 to be applied constantly while you shake (and you'll hear more CO2 coming from the tank as you shake the keg); during that shaking time CO2 is being absorbed into the beer, so you need to keep the pressure in the airspace.

edit: So, when we carb our beer, we put a certain volume of CO2 in it per volume of liquid, correct? So based on that, depending on how much beer you are carbing, we can calculate how much CO2 we need for a given carbonation level. Here's what I propose: can't we estimate the amount of headspace in our kegs (the volume) and using that, estimate what pressure we need to apply to the headspace in order to accomplish the aforementioned volume of CO2?
You're correct I believe, but it would be a very high pressure you'd need to apply at the outset which would exceed the limits of the corny keg I reckon.
 
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It depends on how much carbing you want and what the temp of the beer is. I was able to "batch carb" by pressurizing my headspace to 70psi and leaving it alone for two days (no additional gas connected).
 

mltunmaster

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The numbers may work in practice, but not because the method of calculation was logical ;-)
The rate of absorption is not linear at all. It starts faster due to the pressure delta between headspace and beer and slows as it gets closer to equilibrium. If someone is smart enough, I think calculus would be involved. I am not that guy.
Maybe we can get Professor FLJohnson to do the math.
I thought this thread was great, lots of information I can use.
 
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I've been working on some graphics and presentation materials to explain the various methods and pros and cons of force carbing a keg and would like some feedback on the overall concept and artwork before I do the whole thing. Here's one slide's worth.
 
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Do you get the visual that the beer-filled keg on the right has twice as many CO2 molecules in it than the one on the left or is it too subtle?
 

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Has anyone ever tried chilling a keg, setting to serving pressure (maybe 12 psi), shaking the hell out of the keg? It seems to me like you couldn't possibly overcarb since you're only putting 12 psi on it, yet at the same time you're increasing that surface area that's in contact with the CO2. I might experiment with this when I keg my very first batch tomorrow. I'm kinda on the fence whether to set and forget or burst carb. This might be a happy medium to have a drinkably (yeah, think I just made a word up) carbed beer without all the waiting of set and forget and zero risk of overcarbing. Thoughts? :mug:
 

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Do you get the visual that the beer-filled keg on the right has twice as many CO2 molecules in it than the one on the left or is it too subtle?
I did. Might just want to add a little bubble saying that just incase someone misses it.
 
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Has anyone ever tried chilling a keg, setting to serving pressure (maybe 12 psi), shaking the hell out of the keg? It seems to me like you couldn't possibly overcarb since you're only putting 12 psi on it, yet at the same time you're increasing that surface area that's in contact with the CO2. I might experiment with this when I keg my very first batch tomorrow. I'm kinda on the fence whether to set and forget or burst carb. This might be a happy medium to have a drinkably (yeah, think I just made a word up) carbed beer without all the waiting of set and forget and zero risk of overcarbing. Thoughts? :mug:
Yes, it will shave some time off. I call that a "target pressure shake". I've been trying to figure out exactly how to name all these nuanced methods.
 

jb721

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Yes, it will shave some time off. I call that a "target pressure shake". I've been trying to figure out exactly how to name all these nuanced methods.
Right on, just plugged in the new beer fridge when I got home from work this morning and I haven't yet checked to see how cold it gets. I hooked up a 5 gal keg with a 2.5 gal batch of beer in it (just graduated from mr beer) at 12 psi. Shook it a little but mainly was focused on my first 5 gal batch. Might go check on it and see how cold that fridge is and bust out the handy dandy table to see if 12 psi was a good guess. Thanks! :rockin:
 

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Great thread Bobby. I'm just finishing up my 3 tap keezer build and kegged my first two batches the other night. I simply sanitized, racked, lubed the o-rings, hooked up the CO2 and bled out the O2 for 20 sec., and then sealed at 20 lbs. I'm going to let the kegs sit at room temp. for a another week or so until I finish the grouting and sealing of the stone tile on my keezer top. My keezer will be set at 38 degrees and I have another temp. probe in my coffin along with inductor fans to keep the coffin at 43 degrees (trying to maintain a 5 degree or less temp. differential). Once the keezer is completely finished, I plan on bringing the kegs down to temp. over a couple of days, using 30 PSI for 24 hrs., bleeding off the excess pressure and backing down to 11 PSI and leaving it for another week or so. I'm in no hurry, and I don't want to screw this up.

My concern at this point is that my Keezer is a frickin' tank! The lid is heavy as hell and I don't want to have to keep moving the unit and opening the lid to make countless adjustments. My set up from kegconnections.com came with 6 foot long, 3/16" serving lines. My instincts are telling me that this length of line is not sufficient in balancing the system. Granted, I do have slightly over 3 feet of rise from mid keg height to the Perlicks. Bascially, I want to be able to serve at the carbing PSI of 11 and I don't want to have to drop it down or keep making adjustments. Is 6 feet of serving 3/16" serving line with about 38 inches of rise at 38 degrees at 11 PSI going to lead to a major foaming issue? I'll take any input, but if the concensus is that I'm going to have foaming issues, then I may just bite the bullet and purchased longer lines before I hook everything up. I just don't want the frustrations of having an unbalanced system. Thanks guys! :mug:
 

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I am in the same boat here, 5' lines from KegCowboy. What is the proper dispensing pressure for 5' lines?
 

BigB

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I have 5' lines (Kegconnection.com) as well and I just followed the chart Bobby originally posted. My beers are perfectly carbonated and pour at a perfect rate.
 
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