Keg Force Carbing Methods Illustrated

I'm still kind of a newb (only been brewing about 5 months, 8 batches) and am just about to get into kegging.

Looking for someone to correct me if I'm wrong. From what I know, burst carbing seems to be an entirely valid method depending on your setup. The two concerns I saw in the OP are possible overcarbonation and the beer not being aged enough, so "why burst carb at all?":

1.) Is it not possible to get approximately the volume of Co2 that you want by using a pressure gage connected to the gas-in? The process I plan to do is the standard shake-at-30-psi method, very conservatively, then detach the co2, shake the keg more, read pressure gage, and repeat until I get consistent readings (the carbonation will be in equilibrium and it should represent the pressure that's in solution). Then reattach the co2, and repeat the whole process, until I get the carbonation I want.

2.) If someone has a small/modestly-sized kegerator, and a decent amount of fermentation vessels, it doesn't seem at all to be poor planning to age the beer in the fermenters and burst carb carefully and accurately. In fact, that would seem to make the most efficient use of a kegging system by having only ready or almost ready (cold crashing, etc) beers hooked up. Kegging equipment gets expensive the more servicable kegs you add to the system. Buckets are cheap.

The first post in this thread seems very down on burst-carbing, but to me it seems that it can represent a great solution to make the most out of one's equipment. I'm posting this because I may be missing something, so if I am, please let me know!

Thanks!

Jake8078 said:

1.) Is it not possible to get approximately the volume of Co2 that you want by using a pressure gage connected to the gas-in? The process I plan to do is the standard shake-at-30-psi method, very conservatively, then detach the co2, shake the keg more, read pressure gage, and repeat until I get consistent readings (the carbonation will be in equilibrium and it should represent the pressure that's in solution). Then reattach the co2, and repeat the whole process, until I get the carbonation I want.

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Shaking does force equilibrium faster than having it sit around, but it's very possible to end up reading a head space pressure that's higher or lower than the partial pressure of dissolved CO2. For your purposes, it could be close enough.

Jake8078 said:

2.) If someone has a small/modestly-sized kegerator, and a decent amount of fermentation vessels, it doesn't seem at all to be poor planning to age the beer in the fermenters and burst carb carefully and accurately. In fact, that would seem to make the most efficient use of a kegging system by having only ready or almost ready (cold crashing, etc) beers hooked up. Kegging equipment gets expensive the more servicable kegs you add to the system. Buckets are cheap.

The first post in this thread seems very down on burst-carbing, but to me it seems that it can represent a great solution to make the most out of one's equipment. I'm posting this because I may be missing something, so if I am, please let me know!

Thanks!

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I wrote the first post and I am in the anti-burst camp, especially when it comes to the combination of elevated pressure and shaking. Just like anything else, much of this stuff is preference and opinion and this threaded started with mine. You don't have to agree. Many don't and have shared their methods in the thread.

To deal with pipeline issues, you can also use an aux tank/regulator and let them sit at the appropriate pressure for room temps or wherever you age your on deck kegs. There are also compromise solutions like non-shake elevated pressures (for short periods like 24 hours) and/or shaking at chart pressures. Certainly one of the benefits of the set and forget method is the long period of cold aging you're forced into and that really clears the beer well in cases where you can't cold crash or cold age the fermenters. If you really want to carb it quick and start drinking, I'd want to have a fermentation temp controlled area where you can let it ride at 35F for a week before transferring to keg.

Read about how shaking a bottle that is already in equilibrium doesn't change the pressure in the bottle. It forms bigger bubbles that explode to the surface when opened. Then in the IPA book read that, "If injecting CO2 to carbonate, do so gently to avoid forming large bubbles that strip hop flavor from the beer."

Putting these two together would make me think that shaking your hop forward beer kegs is a really bad idea.

I set and forget at 12 psi and the keg gets very drinkable at 5 days, 7 and I'm digging in. The temp of your fridge is not the same as the temp of your beer. Put a glass if water in the fridge and test it with a liquid thermometer.

hops2it said:

Just to report back, I had great success with the 30 psi for two days, then reduce to serving psi method. Most definitely will be my modus operandi moving forward. I was drinking beer in 4 days from kegging and it tastes great. I now plan to pull a pint every day for the next couple weeks to check for improvement over time. Who am I kidding though, I'd be pulling those pints anyway, the improvement thing is just an excuse.

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^^I posted the above in this thread back in June, 2012. I was all pumped up at the time but I felt the need to clarify my original statement. As the days went on, the beer got better. Sure enough, even using burst carb (or arguably a hybrid method), it was nearly 2 weeks before the beer reached what I would call ideal.

Moral of the story for me...I'll still use the 2 day method if I really need to get some beer in production. Otherwise, set it and forget it will be my mantra moving forward. Pretty much exactly what Bobby said in the OP is what I found to be true.

hops2it said:

^^I posted the above in this thread back in June, 2012. I was all pumped up at the time but I felt the need to clarify my original statement. As the days went on, the beer got better. Sure enough, even using burst carb (or arguably a hybrid method), it was nearly 2 weeks before the beer reached what I would call ideal.

Moral of the story for me...I'll still use the 2 day method if I really need to get some beer in production. Otherwise, set it and forget it will be my mantra moving forward. Pretty much exactly what Bobby said in the OP is what I found to be true.

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You can lead a homebrewer to beer but you can't make him wait for it to peak.

Bobby,
Thanks for taking the time to post this chart. I'm new to kegging and make my wife Non-alcoholic root beer pretty often too. The burst carbing method for the root beer completely elimiates the need for yeast and any possibility of alcohol in her drink. I for one certainly appreciate your efforts to make this hobby understandable for those of us who are less edumacated than others.

Wheelchair Bob

Question about naturally carbing kegs here:

I'm putting beer in my first keg this week and I plan on using priming sugar because- I don't mind a little extra sediment, like the carbonation of the naturally carbed beers more, and anticipate getting co2 to be a pain in the a$$.

My concern is that if the keg is sealed with co2 before resting at room temperature for a couple weeks, are you purging the head space of the necessary o2 for the yeast to consume and carbonate the beer?

Also, any other advice or reasons not to use this technique I may have overlooked would be greatly appreciated! Thanks for the great info everybody, and especially BobbyM.

Andy

The yeast don't need oxygen to produce carbon dioxide, so purging the headspace is perfectly safe. Also, not purging it is probably fine, since the yeast will consume whatever oxygen is there. Others might have other experience or reasoning, but that's my 2 cents. Cheers!

When I naturally carb in my kegs, should I purge the O2 and apply enough pressure with the CO2 to insure I have a good seal. I did a non alcohol root beer and the keg didn't seem to seal tightly so it had no carbonation and tasted very slightly of alcohol. I poured out the batch because children and youngsters might have been exposed to drinking it and I didn't want to take a chance and end up giving alcohol to a child. Recommended procedure to insure the keg seals and the CO2 stays in solution?

Wheelchair Bob

Getting ready to keg my first batch and will use 30 lbs for 24 hrs and then purge and decrease pressure to 12 lbs for however long it takes...

Should I bring the keg to serving temp before I hit it with 30 lbs or just start at the 67 degrees I am fermenting at and let it cool down to serving temp while I am at 30 lbs?

Either way works, I would just hit it with the 30 and start cooling it right then, no point in waiting overnight or however long it takes to chill down, might as well get it carbing ASAP then turn it down to 12 after 24-36 hours

Anyone can tell from my number of posts I am a noob. I kegged my first beer last Saturday. I blasted 48 hours at 30 PSI and cut back to ~10 psi after that. Result: massive foam no carb in beer.
I have left it at about 8 psi for most of the rest of the week and have discovered yesterday afternoon that my two beers are now holding a little carbonation in them.
Now Mind you I did cut the gas totally and vented out most of the pressure. The beer behaved a little more after that.

I am using hoses that are less than 5' long and I do not recall the ID of the hoses off hand. This is why I am using 8 psi or less to serve.

My next kegged batch I MIGHT try 30 psi for 24 hours. mind I said MIGHT. More likely I will practice the tried and true "set and "Forget" method. Lets face it.. it is hard to forget about a brewing/carbing beer when they are so close at hand.

Almost everyone uses more than 5 feet of hose to balance their lines

I think the very base problem here is that many people get into kegging almost exclusively under the impression that they can get to drinking the beer faster. While it can be achieved with experience, assuming the beer was properly aged and cold crashed previously, it's actually not that easy to do. If all keg kit vendors would just add a few feet of line per faucet and noobs would exercise a little more patience, the beer gods would be smiling.

torso said:

Question about naturally carbing kegs here:

I'm putting beer in my first keg this week and I plan on using priming sugar because- I don't mind a little extra sediment, like the carbonation of the naturally carbed beers more, and anticipate getting co2 to be a pain in the a$$.

My concern is that if the keg is sealed with co2 before resting at room temperature for a couple weeks, are you purging the head space of the necessary o2 for the yeast to consume and carbonate the beer?

Also, any other advice or reasons not to use this technique I may have overlooked would be greatly appreciated! Thanks for the great info everybody, and especially BobbyM.

Andy

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I just started doing this a few months back. First two kegs i did worked out well. Added priming sugar pumped in 10 psi to make a good seal then let it sit at room temp. When i placed ibto fridge i purged to 10 psi connected co2 and let sit for another 3 day. I havent had any problems doing it this way, yet. Only challege im experimenting with is using a poor mans beer gun with naturally carbed keg and seeing if i get enough co2.

I started doing the calcs to show how Fick's laws of diffusion would generate a time-concentration profile along the length of the keg. Results were quite far off from my casual experiments. Some research, and particularly a paper I read on CO2 concentration and density of seawater, led me to quit the demonstration, as I realized that the convection induced by this density increase would swamp the results given by Fick's laws. I don't know enough about fluid dynamics to apply influences from this convection to a CO2-beer scenario. It's fairly complex and I imagine computers would be of help. I'm mostly a solid-state chem/do it all with pen and paper kind of researcher. So I give up and am now having some Deschutes....

If I want to do the patient method, set at 12 psi (at 40 degrees) for 2-3 weeks will I go through a ton of CO2? I only have a 2.5# tank so would hate to run out. Maybe I should get a back-up before attempting to keg.

natefrog255 said:

If I want to do the patient method, set at 12 psi (at 40 degrees) for 2-3 weeks will I go through a ton of CO2? I only have a 2.5# tank so would hate to run out. Maybe I should get a back-up before attempting to keg.

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You should use the same amount of CO2 either way - unless there's a leak in your system there should be nowhere for the gas to go but into your beer. Ultimately it will reach an equilibrium point where no more CO2 will go into the beer at that temp/PSI. Whether it reaches that state quickly (because you shook it or set it to a much higher PSI for a little while) or over a few weeks (evidently how long it takes if you set and forget) the beer should end up with the same amount of CO2 in it, and your tank should be depleted by only that amount. Of course once you start serving more CO2 will be required to fill the space left by the served beer.

I would say keg now, but also go get a backup tank soon. Nice for when you run out, and if you can get a second regulator it's also nice to have as a second CO2 source not tethered to your kegerator for cleaning, purging, and even carbing at room temp if you run out of keg space (slower and requires a higher PSI setting to get the same amount of CO2 into solution in a 65 degree room, but it still works and shouldn't use any more CO2 than carbing at lower temps).

fosaisu said:

carbing at room temp if you run out of keg space (slower and requires a higher PSI setting to get the same amount of CO2 into solution in a 65 degree room, but it still works and shouldn't use any more CO2 than carbing at lower temps).

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Will be faster at higher temps actually....

StMarcos said:

Will be faster at higher temps actually....

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Explain that one for me.

Molecular movement is faster at higher temperatures meaning the CO2 molecules that have just dissolved at the surface of the beer will be moving out of the way faster to allow for new CO2 to dissolve.

The CO2 diffuses into solution faster at warmer temps, however, colder temps allow more CO2 to absorb into solution - which is what allows for the "burst carbing" at higher pressures.

if you wanted to "burst carb" at warmer temps, it would in theory be quicker, BUT you would have to set your regulator to 40-60 psi which isn't very practical or safe

Bobby_M said:

Molecular movement is faster at higher temperatures meaning the CO2 molecules that have just dissolved at the surface of the beer will be moving out of the way faster to allow for new CO2 to dissolve.

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DustBow said:

The CO2 diffuses into solution faster at warmer temps, however, colder temps allow more CO2 to absorb into solution - which is what allows for the "burst carbing" at higher pressures.

if you wanted to "burst carb" at warmer temps, it would in theory be quicker, BUT you would have to set your regulator to 40-60 psi which isn't very practical or safe

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Ok, that makes sense. I was actually pondering the molecular speed idea. Most people that are carbing with high pressures at room temp are shaking anyway though, at least at first.

https://en.wikipedia.org/wiki/Mass_diffusivity

See first equation under the Temperature Dependence heading

T goes up, D goes up.

That the equilibrium concentration decreases as the temp goes up is a thermodynamic issue. The rate at which it approaches that concentration is a kinetic one. Both diffusion and density driven convection play a kinetic role in the case of an upright keg. Both processes are faster at higher temperatures however.

DustBow said:

The CO2 diffuses into solution faster at warmer temps, however, colder temps allow more CO2 to absorb into solution - which is what allows for the "burst carbing" at higher pressures.

if you wanted to "burst carb" at warmer temps, it would in theory be quicker, BUT you would have to set your regulator to 40-60 psi which isn't very practical or safe

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Why wouldn't it be safe? Cornie kegs are rated to 129psi. So they have been tested to at least twice the rated PSI.

I keep mineral water in a corny at 40psi CO2.

Actually what allows for faster carbonation at higher pressure is also 2-fold. Density will be greater at the surface due to higher CO2 concentration at the interface, increasing the convective transfer. In addition, the diffusion flux will be greater as per Fick's laws,

https://en.wikipedia.org/wiki/Fick's_laws_of_diffusion

The first equation under each of the two laws demonstrate the increased mass transport due to increased concentration.

crazyirishman34 said:

Why wouldn't it be safe? Cornie kegs are rated to 129psi. So they have been tested to at least twice the rated PSI.

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I guess "safe" might not be the right word. It's just that you don't often hear of guys putting much more than 30 on beer. You're right in that the kegs are rated pretty high, they're rated higher than the regulators. Some keg lids also have pressure relief valves that will blow when pressure gets too high

StMarcos said:

Will be faster at higher temps actually....

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Even better!

I just point it out because I use mine to carb ginger beer and root beer and you need to give it 60psi to get the right fizz

CrazyIrishman,
Wow! I only brew soda but have been having carbonation problems up the wazoo (tons of foam in my lines and flat soda). I have never tried putting 60PSI into my sodas though. Do you upping my PSI would do the trick?

Kyle

You need to make sure that your soda is dispensed at 32deg f or lower. Other wise you will have foaming and break out. Leading to flat soda. What I normally do is carb the soda at 60psi for a couple weeks until it is as fizzy as I like then back down to 20psi to push it.

I've never heard of kegging soda for a few weeks. That seems like a really long time to tie up a keg (especially for me since I have only 1).
I'll try jacking up the pressure and then dialing back to 20PSI for bottling.
Do you agitate the keg to carb quicker?

Kyle

nope just let it sit at 60psi for a couple weeks. It might be ready sooner but I take my time with it. I have like 20 kegs so I don't have to rush

Jealous! I might be scoring a friend's fridge tomorrow so I can get another corny keg or two.
Some of the sodas I am working on use real fruit juice. I hate the taste of sodium benzoate and haven't found a good preservative. I would guess that after a few weeks of carbing my sodas would probably spoil. Any thoughts on that?

Kyle

Brewconcepts said:

CrazyIrishman,
Wow! I only brew soda but have been having carbonation problems up the wazoo (tons of foam in my lines and flat soda). I have never tried putting 60PSI into my sodas though. Do you upping my PSI would do the trick?

Kyle

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I'd definitely recommend getting proper length lines for your soda. You should also consider adding 2 mixer sticks to the tube in your keg (discussed in this thread). I did that and went from serious foaming problems (like you describe, foamy pour and then no carb in the beverage) to zero foaming problems with my root beer (which i was having even with longer serving lines).

As for carbing, I've had success doing this:

• Chill keg to serving temp (I do 38 since that's what I serve my beers at)
• Put on gas at 35 PSI and roll the keg on the ground for a few minutes. For me this gets it pretty close, though it'll still absorb more as you leave it on gas in your kegerator. This should allow you to serve promptly without worrying about your fruit juices spoiling.
• Leave it on 35 PSI for serving (I know some people carb high and serve low but that's only ever made the foaming worse for me), which shouldn't give you trouble if your lines are long enough.

I have one of the Epoxy mixers I got a few months ago but never put it in. I just brewed up a batch and put the Epoxy mixer in the dip tube. In a couple days, I'll report back.
Also, my hose IS long: 25' of 3/16" tubing. Hopefully things will be different with the Epoxy mixer, but the long hose didn't help much on its own. I got crazy pressure and I had to really force my Blichmann beer gun closed when bottling.

Reporting back soon,
Kyle

Brewconcepts said:

I have one of the Epoxy mixers I got a few months ago but never put it in. I just brewed up a batch and put the Epoxy mixer in the dip tube. In a couple days, I'll report back.
Also, my hose IS long: 25' of 3/16" tubing. Hopefully things will be different with the Epoxy mixer, but the long hose didn't help much on its own. I got crazy pressure and I had to really force my Blichmann beer gun closed when bottling.

Reporting back soon,
Kyle

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Sorry, didn't see that you were trying to bottle the sodas off the keg. In that case you'll definitely need to turn down the serving pressure while bottling (though in my experience you can leave it high when serving into a normal drinking vessel).

I need to experiment with mine... I think it will be ready tomorrow, sitting in the beer fridge under 20 PSI for the next 24 hours.

In the original post of this thread, a carbonation chart is referred to. If I use this chart and carbonate using method #1, set and forget, do I need to make any adjustments for head space? Asked differently, should I do anything different with a 5 gallon keg that is half full of uncarbed beer vs. a 5 gallon keg that is 100% full of uncarbed beer?