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 Home Brew Forums > Keg Force Carbing Methods Illustrated
09-15-2011, 04:11 AM   #411
peterlonz
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I'm new to the keg & pressure carbonation techniques despite 40 years of brewing.
I have been surprised at the confusion of principles (of Physics that is) that feeds into well meant advice, much of it wrong but repeated again & again.
I appreciate the care effort that was put into this original post by Bobbi but I did have some difficulty with another measure he introduces & which I have not seen before.
IE the concept of carbonation expressed in volumes, volumes of what I thought; oh yes I guess he means the keg volume.
I ask is it not simpler to talk about the equilibrium pressure that should be aimed for for at various storage temperatures.
Achieving that & allowing some conditioning time certainly supports "the green line" method.
My problem is I still don't exactly grasp what you actually do to obtain this result.

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09-15-2011, 05:18 PM   #412
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peterlonz: Volumes of CO2 is a reference to the amount of CO2 gas that is dissolved in a liquid solution. For example 1 volume of CO2 is defined as: 1 liter of CO2 disolved in 1 liter of liquid at standard temperature and pressure... it is based on "Henry's Law." Therefore, to answer your question, if I understand it correctly, the pressure is merely what you use to obtain the desired density of CO2 in the beer. To obtain the equillibrium as represented by the green line, you would simply find on the chart what volume of CO2 you want in that beer, cross reference that on the chart to what temperature your beer will be at while you are carbonating the beer. Then that will tell you what pressure you need to use to obtain that equillibrium.

For example... say you have a beer that you want to carbonate to 2.2 volumes of CO2. You were going to have that beer at 42F while it was carbonating. The chart would tell you to set the pressure (which is your equillibrium pressure) at 10 psi. Then all you need to do to obtain the "green line" is to set your pressure at 10 psi, leave it at the 42F for approximately 2-3 weeks, and voila, you have obtained the equillibrium.

The other lines show you what happens when you increase the pressure... that the increased pressure may result in reaching your desired volume quicker, but also that you risk overshooting your desired volume because of the increased pressure.

EDIT: Bobby provided the chart in his first post... here is the link he provided: http://www.kegerators.com/carbonation-table.php

So for my example, looking at the chart, you would look on the left side for your temperature, then follow that row over to the right until you find your desired volumes, then follow that column up to find your pressure.

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09-15-2011, 06:49 PM   #413
CidahMastah
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If you are patient, don't have a pipeline and have a large keezer you might be able to pull off the set and wait to get to your desired pressure. I however have a pipeline, and when I replace a keg, I would like to drink from it in a few days, because it has already conditioned while it sat in line. Once you start having kegs on deck you will be looking to decrease the time from hook up to correct carb and pour.

To answer your question, getting a keg to a desired volume of CO2 (equalized) is very easily done. Use the above referenced chart. Balancing your system with beer line for dispensing can be tricky. They are two different things though.

Dispensing it can be an issue. If you set your hefe for say 3.5 volumes and use a 5ft beer hose, you are going to get foam like crazy when you dispense it. This is were some of the issues come in. You need to match line resistance on your dispense roughly with your carb to avoid this issue. I do this by adding line resistance with the epoxy mixer sticks, or I have one very long line that I use to tap higher carb brews such as hefes.

So you can't talk about keg carbonation equalization with out keg dispensing balancing. You would only get half the picture

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09-16-2011, 06:45 AM   #414
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A boy new to kegging, asking for a bit of clarification on several points:
1) The keg refrigeration temps referred to here are very low generally 32 to 35 Deg F which is very close to freezing.
I think I can get my fridge to do that at a push but how important is it if you are not in any great hurry & plan 2 to 3 weeks for conditioning.
2) If I hold my keg at about 40-42F & apply 30 psi can I achieve satisfactory carbonation in say a week.
3) After whatever period it takes to carbonate at these temps, what maintenance pressure should I choose, I was thinking maybe about 10 psi?
4) Speaking practically about how cold the beer should be when dispensed from a keg, IE a good drinking temperature for ale; what then is the ideal fridge/keg contents temp?
Thanks

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09-16-2011, 07:49 AM   #415
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Quote:
 Originally Posted by peterlonz A boy new to kegging, asking for a bit of clarification on several points: 1) The keg refrigeration temps referred to here are very low generally 32 to 35 Deg F which is very close to freezing. I think I can get my fridge to do that at a push but how important is it if you are not in any great hurry & plan 2 to 3 weeks for conditioning. 2) If I hold my keg at about 40-42F & apply 30 psi can I achieve satisfactory carbonation in say a week. 3) After whatever period it takes to carbonate at these temps, what maintenance pressure should I choose, I was thinking maybe about 10 psi? 4) Speaking practically about how cold the beer should be when dispensed from a keg, IE a good drinking temperature for ale; what then is the ideal fridge/keg contents temp? Thanks
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09-16-2011, 12:04 PM   #416
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Quote:
 Originally Posted by peterlonz 1) The keg refrigeration temps referred to here are very low generally 32 to 35 Deg F which is very close to freezing. I think I can get my fridge to do that at a push but how important is it if you are not in any great hurry & plan 2 to 3 weeks for conditioning.
I keep mine at about 43F. But I do mostly ales, and I prefer them a bit warmer.

Quote:
 Originally Posted by peterlonz 2) If I hold my keg at about 40-42F & apply 30 psi can I achieve satisfactory carbonation in say a week.
Might be overcarbonated. I'd go with either maintenance pressure (on a balanced system) for a few weeks or 35 PSI for 24-48 hours, purge, then maintenance pressure for a week or so.

Quote:
 Originally Posted by peterlonz 3) After whatever period it takes to carbonate at these temps, what maintenance pressure should I choose, I was thinking maybe about 10 psi?
That depends on your setup, length of beer lines, etc. There are a large number of posts dedicated to that on the forum. Search.

Quote:
 Originally Posted by peterlonz 4) Speaking practically about how cold the beer should be when dispensed from a keg, IE a good drinking temperature for ale; what then is the ideal fridge/keg contents temp?
Depends on your preference. Many say 38F. Of course, some joints keep their brews at 29F. I keep mine at 43F and sometimes even 45F. Especially in the winter when I like my darker ales. I prefer them warmer so some of the notes come out.
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09-16-2011, 12:48 PM   #417
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1. You can always let a beer warm up, you can't chill it easily after poured (I think that is why many folks go for low temps). 2-3 weeks at whatever temp + PSI for volume desired based on the volumes of carbonation chart that was previously posted. If you read that chart that was posted you will notice the warmer the beer the higher the PSI to carb it initially. I.e. lower temps allow you to get co2 in at a lower pressure.

2. This is where things get tricky based on temp of keezer, etc. Might take some experimentation on your part. From my anecdotal experience I agree, you will be way over carbed. If you boost, you should only do it for a limited time then stop and switch to maintenance pressure.

3. Your maintenance pressure depends on:
a. Your desired volumes and temperature in the keezer (see that chart we keep telling you to look at).

*Your lines on your system will have to be adjusted AFTER and have nothing to do with your carbonation level of volumes. Lines provide restriction so your brew doesn't fly out foaming.*

i.e. if you carb a hefe at 4 volumes and an ale at 2.5 volumes, you will need a longer hose, or mixer sticks to dispense the hefe at the same pour rate than you would the ale. Your maintenance pressure for the ale and the hefe would be different in a balanced system (dependant on brew temp).

You need to determine the carb level you want, let it get to that carb, then dink around with your hose length until you get it right. I.e. start with a long hose and pour, cut it back a foot at a time until you get the pour you are looking for. How long to start with? depends on the hose brand. If bevlex, start with 15ft for a standard pour right near the draft with no rise system.

4. Just as with above, depends on what you like. I go lower because I pump brew up a story to my living room and when it pours out I get around low 40's for a serving temp. Most people say 38F is sanitary for long term. However, unless you are planning on having kegs on tap for 6 months+ I down this will ever play into your setup.

This sounds complicated but it isn't.

2. Use the chart and pick your desired carb.
3. for the set and forget method, set your PSI to the level you need, leave it for 2-3 weeks.
4. Start with a longer beer line and pour. Too slow? cut a foot off and try again. Too fast? your line is too long - start over with longer line.

Once you get the hang of that you can fool around with the boost method many people use here.

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09-18-2011, 01:44 AM   #418
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Hi,

I'm new to kegging and I'm trying this technique for force carbing (30psi for 24h then normal pressure - no shake). Tonight's the first night I've dialed up the pressure to 30psi and one strange thing I'm seeing is the pressure readout on the CO2 is slowly creeping down each hour. I'm afraid this might mean I have a leak somewhere but I've soaped up the works and haven't found anything.

One variable is that my CO2 tank was warm when I started but it went into the fridge along with the keg when I dialed up to 30psi. Could this be the tank adjusting or do I really have a leak somewhere? Or something else perhaps?

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09-19-2011, 05:02 PM   #419
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Quote:
 Originally Posted by Framnk Hi, I'm new to kegging and I'm trying this technique for force carbing (30psi for 24h then normal pressure - no shake). Tonight's the first night I've dialed up the pressure to 30psi and one strange thing I'm seeing is the pressure readout on the CO2 is slowly creeping down each hour. I'm afraid this might mean I have a leak somewhere but I've soaped up the works and haven't found anything. One variable is that my CO2 tank was warm when I started but it went into the fridge along with the keg when I dialed up to 30psi. Could this be the tank adjusting or do I really have a leak somewhere? Or something else perhaps?
I (think) I notice my pressure going UP when I put the cylinder in the frig. Just check it every couple of hours and adjust to keep at 30 psi for the 24 hours.

I've done this many times, and it works great.
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09-27-2011, 04:44 AM   #420
peterlonz
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Framnk,
As it happens you are not alone, the almost exact same thing is happening to me.
If you have set your regulator to 30psi then unless you are running out of CO2 you should not see any drop in keg pressure. This assumes you have not charged to 30 psi then shut off the CO2 delivery from the gas cylinder - you definitely should not do this whilst carbonating at constant supply pressure.
I suspect therefore you are running out of CO2 & AFAIK the only way to check this effectively is to weigh your cylinder. I hope you know the empty weight because I have found stamped on Tare Weights to be wrong in some cases. I guess it could depend upon exactly the definition of Tare Weight.
Anyway you get the drift: you need also to be aware that your gas cylinder will show substantial pressure right up to the "very near empty" point due to the liquid/gas phase mixture properties.
The easy method is to make a warm water & liquid detergent mix that will readily form suds. Use a 2 inch paintbrush & generously apply the sudsy mixture by brush over every joint whilst holding pressure. Leaks will show by blowing large bubbles which you should be able to see. When finished wash off the mixture, you do not want detergent hanging around.
A better method but not quite so easy is to dunk everything (yes everything - CO2 cylinder, Keg, pressure lines etc, you don't need the dispensing tap & line because if this was leaking you would see brew entering the line), in your swimming pool & look for bubbles.
No bubbles - no leaks.
Hope that helps.

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