Force Carbonating A 9l Keg

[T.D.]

To date I have only force carbonated 18L kegs. I find that 200kpa for 36 hours gets me the carbonation level I am after. I will be needing to carbonate a 9L keg in the next few days and I was just wondering if the process is any different? I assume it will take less (either time or pressure) to gas up 9L of beer compared to 18L but is there some kind of rule of thumb for this? Do I simply halve the time or pressure (ie 36hrs @ 100kpa, or 18hrs @ 200kpa) or is it done exactly the same way as an 18L keg?

Cheers,

:beer:

 

[Wortgames]

Don't make me get the wooden spoon.

You have the same surface area but half the amount of beer. So at 200kpa it will carbonate a lot faster - probably around half the time, but I'm guessing.

The easiest way is to set your equilibrium pressure (eg 90-100kpa) and leave it connected permanently. It will carbonate by itself in a few days.

If you're in a hurry then crank the pressure up and shake the keg, this will increase the rate of absorption. But if you are looking for a hard and fast rule to achieve perfect carbonation by blasting pressure into it at a high rate, there isn't one.

The best bet would be to 'mostly' carbonate at high pressure, but then turn the pressure down and let it finish off by naturally carbonating at your equilibrium pressure. It's better to be slightly under your ideal pressure than over it. At least you can pour flat beer.

 

[KoNG]

T dot D dot
I've never forced carbed, so i'm not much help, but in theory i would agree with your assumption of half the pressure/time.
More than happy to evaluate the theory in a practical situation like a tasting session. Let me know when.

 

[warrenlw63]

Probably a more precise method and being a 9 litre keg (less weight to heft) it's probably even easier. Dial your reg to 100kPa (or desired serving pressure). Connect the gas to 3 degree beer. Shake/rock the keg until it stops sounding like a person drowning. Disconnect, put the keg back in the fridge for an hour or so and repeat the sequence 1 or 2 more times over a 3 to 4 hour period.

Similar to WG's method but probably caters for more impatience to sample.

Next don't give KoNG any... I suspect he's greedy.

Warren -

 

[T.D.]

WG, by "equilibrium pressure" do you mean dispensing pressure? I only dispense at 30kpa. Would that be enough to carbonate?

Big k little o big n big g, thanks for your kind offer to help drain the keg, despite having absolutely no advice to offer on the carbonation issue... I think I'll pass this time mate!

Thanks for the advice Warren, I've never tried that method before. The only think holding me back is the fear of overcarbonating. Maybe its time to give it a whirl!

 

[Doc]

I use the same pressure and the same time for all size kegs. 300kpa for 48 hours.
Works on 10 litre, 18 litre and 45 litre kegs. All come out with the right level of carbonation. The bigger kegs just use more gas.

Cheers,
Doc

 

[T.D.]

I use the same pressure and the same time for all size kegs. 300kpa for 48 hours.
Works on 10 litre, 18 litre and 45 litre kegs. All come out with the right level of carbonation. The bigger kegs just use more gas.

Cheers,
Doc

Thanks Doc, that's exactly what I wanted to hear!

Just seemed intuitive that half the volume would take half the time. You see, this is why I am an economist not a scientist! Although... KoNG is a scientist... :lol: :lol:

 

[warrenlw63]

Thanks for the advice Warren, I've never tried that method before. The only think holding me back is the fear of overcarbonating. Maybe its time to give it a whirl!

Nup overcarb is impossible TD. You're effectively carbonating and serving at the same pressure. If anything there's probably less chance.

I find it a bit tiring on 18 litre kegs though. Shaking the crap out of 2 kegs continually for 2-3 minutes is too much like hard work. :lol:

Warren -

 

[T.D.]

Nup overcarb is impossible TD. You're effectively carbonating and serving at the same pressure. If anything there's probably less chance.

I find it a bit tiring on 18 litre kegs though. Shaking the crap out of 2 kegs continually for 2-3 minutes is too much like hard work. :lol:

Warren -

Would it work at 30kpa, or should it always be donw at 100kpa?

 

[Wortgames]

WG, by "equilibrium pressure" do you mean dispensing pressure? I only dispense at 30kpa. Would that be enough to carbonate?

Not unless you want to drink really flat beer!

What I mean by 'equilibrium pressure' is the pressure which results in the exact carbonation you want at the temperature you have. At this pressure, once the beer has absorbed it's particular volumes of gas it won't get any fizzier or flatter. Usually the equilibrium pressure is around 90-100kpa, although it depends on your temperature and how fizzy you want the beer.

If you dispense at less than equilibrium pressure, then you have gas trying to come out of solution due to the reduced pressure. You are highly likely to get foaming problems with a setup like this, plus your beer will gradually get flatter unless you crank the pressure back up again from time to time. If you dispense at higher than equilibrium pressure (which most pubs do), you will not get foaming problems straight away but the beer will get more and more gassy over time until it becomes unmanageable. The trick is to have a 'balanced' system where your keg remains at its equilibrium pressure the whole time, and you don't have to adjust it for serving. This way the keg can remain hooked up indefinitely and still pour perfectly.

Basically you need some more resistance in your lines, so you don't have to reduce the regulator pressure while pouring. That way the system pressure remains contant and the beer isn't trying to lose gas.

At the risk of repeatedly pimping my own wiki entry I tried to explain it here.

 

[T.D.]

Thanks WG, makes much more sense now! Yeah, I am always going to be behind the eight ball on the dispensing pressure thing - I dispense out of those taps that clip directly onto the keg - so no beer line at all! One day I will try and sort out a proper "tap in door" system or a chest freezer with font where I can extend the lines to the right length to allow carbonating and serving at "equilibrium" carbonation. Certainly sounds like that's the way to go if possible.

:beer:

 

[warrenlw63]

Would it work at 30kpa, or should it always be donw at 100kpa?

TD I just carb at my desired serving pressure. So if it's an APA, lager, or similar 100kPa, shake and serve. If it's Bitter, Mild, Stout etc. I usually do it at 60-80kPa.

30kPa ?? ... Mate that's flat. :lol:

Edit: If you mean 300 kPa I'd just do the shake once.

Warren -

 

[T.D.]

TD I just carb at my desired serving pressure. So if it's an APA, lager, or similar 100kPa, shake and serve. If it's Bitter, Mild, Stout etc. I usually do it at 60-80kPa.

30kPa ?? ... Mate that's flat. :lol:

Edit: If you mean 300 kPa I'd just do the shake once.

Warren -

Nah, I mean 30kpa - that's what I dispense at. Just wasn't sure if it was 100kpa(ish) regardless of what pressure you actually dispense at. Might give this method a shot for the 9L keg and see how it goes...