First time kegger - pressure and temperature

[WinoBob]

Hey there,

I'm planning on kegging for the first time, after having bottled my first few brews. Since I don't have enough room in my fridge for the fermenting bucket, I'm planning on transferring the beer from the fermenter at room temp, pressurising the keg (a 9L keg), and placing the keg in the fridge, which is at around 7C/44F. Here are my questions:

1, What bar/PSI should I pressurise the keg to before putting it in the fridge (it's a NEIPA)?

2, For how long does it need to sit at that pressure before I can consider it ready for serving?

3, What should I reduce the pressure to before serving, and...

4, Does it need to sit at serving pressure for a while, or am I good to go as soon as I set the serving pressure?

Thanks in advance!

 

[Vale71]

1, What bar/PSI should I pressurise the keg to before putting it in the fridge (it's a NEIPA)?

Here you go:

https://www.glaciertanks.com/carbonation.html

2, For how long does it need to sit at that pressure before I can consider it ready for serving?

That depends on how much CO2 you will actually need to push into the beer (lager<ale) and on the beer's temperature (like always, colder = slower).

3, What should I reduce the pressure to before serving, and...

Never reduce pressure unless you only want to serve foam.

4, Does it need to sit at serving pressure for a while, or am I good to go as soon as I set the serving pressure?

Question makes no sense.

 

[day_trippr]

4 makes sense in the context of the belief that 3 makes sense

Use chart pressure from cradle to grave and the beer will always be correctly carbonated and will stay that way.
Design the dispensing system to handle that pressure and all will be right in the land...

Cheers!

 

[mongoose33]

You need to keep the beer under pressure for it to carbonate. If you just pressurize it to, say, 30psi, the beer will absorb the CO2 and the pressure will equilize at some level (depending on temp of the beer). You need it connected for the duration of the time needed to carbonate it.

Cold beer absorbs CO2 more readily than warm beer. Usually we talk about beer's carbonation in "volumes" of CO2. For instance, I often aim for 2.5 volumes of CO2.

Look at the chart below. Suppose my beer is warm, at, say, 63 degrees. If you look at the line marked 63 degrees, and look on that line for 2.5 volumes and then see what pressure (psi) corresponds to that, you'll see it's between 26 and 27 psi.

It'll take a week or two at that pressure for the beer to fully carbonate. Then, suppose you take that now fully-carbonated beer and chill it to 38 degrees. Reading across the chart at 38 degrees, and finding the 2.5 volume figure, it's between 11 and 12 psi--or a fairly typical pressure for cold beer.

So you need to know your temps, your desired volumes of CO2, and the time necessary to carbonate. Many brewers will do something like this: set the temp at (again, for example) 38 degrees, set the regulator at 12 psi, and they'll end up with 2.57 volumes of carbonation when it finishes.

This "set and forget" process can take up to 2 weeks for the beer to fully carbonate. An alternative is to force carb the beer to get it there faster. I'll sometimes do this: I'll crash the beer to 38 degrees, then put it on 30 psi pressure for 24 hours. Then I back it down to the 12 psi I want. This will get you there in a couple days. You want to be careful you don't overcarb the beer, because, well, you don't. Foam, too carbonated, it's a nightmare. So I'll tend to undershoot, and let the set-and-forget method finish it.

 

[WinoBob]

Here you go:


Never reduce pressure unless you only want to serve foam.


Question makes no sense.

Could've sworn I read that you usually reduce pressure before serving. I may have been high, though. Thanks for the response!

 

[WinoBob]

You need to keep the beer under pressure for it to carbonate. If you just pressurize it to, say, 30psi, the beer will absorb the CO2 and the pressure will equilize at some level (depending on temp of the beer). You need it connected for the duration of the time needed to carbonate it.

Cold beer absorbs CO2 more readily than warm beer. Usually we talk about beer's carbonation in "volumes" of CO2. For instance, I often aim for 2.5 volumes of CO2. Suppose my beer is warm, at, say, 63 degrees. If you look at the line marked 63 degrees, and look on that line for 2.5 volumes and then see what pressure (psi) corresponds to that, you'll see it's between 26 and 27 psi.

It'll take a week or two at that pressure for the beer to fully carbonate. Then, suppose you take that now fully-carbonated beer and chill it to 38 degrees. Reading across the chart at 38 degrees, and finding the 2.5 volume figure, it's between 11 and 12 psi--or a fairly typical pressure for cold beer.

So you need to know your temps, your desired volumes of CO2, and the time necessary to carbonate. Many brewers will do something like this: set the temp at (again, for example) 38 degrees, set the regulator at 12 psi, and they'll end up with 2.57 volumes of carbonation when it finishes.

This "set and forget" process can take up to 2 weeks for the beer to fully carbonate. An alternative is to force carb the beer to get it there faster. I'll sometimes do this: I'll crash the beer to 38 degrees, then put it on 30 psi pressure for 24 hours. Then I back it down to the 12 psi I want. This will get you there in a couple days. You want to be careful you don't overcarb the beer, because, well, you don't. Foam, too carbonated, it's a nightmare. So I'll tend to undershoot, and let the set-and-forget method finish it.


View attachment 643432

Thanks for elaborating - very helpful!

 

[day_trippr]

Could've sworn I read that you usually reduce pressure before serving.[...]

As @mongoose33 detailed, if you do a "burst" carbonation to accelerate the process you don't want to hook up your gas and beer lines if the keg is sitting at 30-something PSI. At the best you'll blast spray out the faucet, at the worst - if you over-filled the keg and your gas system lacks a backflow prevention valve - you can force beer up the gas line to the regulator and make an ungawdly mess of things

In that situation you definitely want to release the head space pressure first, set the desire holding/dispensing pressure (from the chart) and then connect the keg. No waiting per se is required, though most folks find after the initial 24 hour burst phase it takes a week or so for the beer to hit its stride...

Cheers!

 

[Vale71]

Could've sworn I read that you usually reduce pressure before serving. I may have been high, though. Thanks for the response!

Yeah, some people still do that without knowing the reason. That's probably because there is no reason at all.

Lowering pressure in the keg below the equilibrium pressure is like opening a bottle and then letting it sit on the table, only it's a big bottle and it will be sitting there for a long time. What this will achieve is that the beer will start foaming and soon you'll only have foam coming out of your taps and you don't want that.

 

[camonick]

Could've sworn I read that you usually reduce pressure before serving. I may have been high, though. Thanks for the response!

You mentioned your temp is 44° and let’s say you want 2.4 volumes of CO2 in your finished beer, using mongoose’s chart above, you will carbonate and serve your beer at 13 psi. I carbonate using the set and forget method and it usually takes about 2 weeks with constant pressure to reach proper carbonation.
To achieve a proper pour, you will have to research how to balance your system. Starting with a minimum of 15’ of 3/16” ID liquid tubing should give you a good starting point.
Sláinte

 

[homebrewcrew]

Could've sworn I read that you usually reduce pressure before serving. I may have been high, though. Thanks for the response!

That’s because most people don’t balance their system. They have a 2 foot beverage line and the only way to get it to pour without foam is backing the pressure way off to like 2-5 psi. You should be able to pour at serving pressure (12psi or so depending on c02 volumes) and get a perfect pour. If you don’t you need to look at balancing your system.

*IMO 10 feet of beer line is the minimum needed to begin to have your system balanced* I run 10ft and Perlick 630SS faucets. Perfect pour every time at ~12psi serving pressure.