From force carbonating to serving pressure, how does it work?

[branCHEs]

12 psi and 3 weeks later i consider my beer fully carbonated.

I want to serve beer at a lower psi to reduce foaming, and personally i don't think beer should be coming that fast any ways.

What is the proper way to accomplish this?

After 3 weeks, drop the psi to the appropriate serving pressure then purge the head space in the keg? Drop the pressure but don't purge? If i do purge, that means there will be less pressure on the beer, will co2 disolve out of the beer because of he pressure differential and lose carbonation?

Any advice from personal experience is much appreciated!

 

[chumpsteak]

You need to match your serving line length to whatever psi you are carbed to. You should strive to serve and carb at the same psi. I use 12 psi with 5ft of 3/16 beerline. Perfect pours.

 

[JuanMoore]

The "appropriate serving pressure" is the same pressure you used to carbonate, 12 psi. If you lower the serving pressure, every time you pour a pint, CO2 will come out of solution to fill the headspace just created, and the beer will lose a little carbonation. It will keep doing this until the carbonation reaches equilibrium with the new lower pressure. Sometimes setting the pressure lower than carb level can also cause CO2 to come out of the lines while it sits, creating pockets of gas. These will create a foamy sputtering first pour of every drinking session. If your beer is coming out too fast, creating foam, you need longer or smaller diameter beer lines. Unfortunately there's no one length that works for everyone. The warmer the beer is, or the more carbonated, the slower the pour needs to be to prevent foaming. People keeping the beer very cold (<39°) and with moderate carb levels can often get by with 4-6' of 3/16" ID beer line. People serving warmer, in the 40-42° range often find they need 10' long 3/16" ID lines.

Here's a spreadsheet you can use to determine what length of line you need for a specific pour speed. I'd shoot for at least a 10 sec pint fill time, and longer if you're going to be serving the beer warmer or using higher carb levels.
https://docs.google.com/spreadsheet/ccc?key=0ApGb-vIKLq7FdGtzN3BrY2xZSldORzQ2bHVVX0hzaEE#gid=0

Two things to keep in mind. There's no disadvantage to extra long lines other than a slightly slower pour, and it's much easier to trim a few feet off of a line that's too long than it is to buy a longer line to replace one that's too short.

 

[branCHEs]

The "appropriate serving pressure" is the same pressure you used to carbonate, 12 psi. If you lower the serving pressure, every time you pour a pint, CO2 will come out of solution to fill the headspace just created, and the beer will lose a little carbonation. It will keep doing this until the carbonation reaches equilibrium with the new lower pressure. Sometimes setting the pressure lower than carb level can also cause CO2 to come out of the lines while it sits, creating pockets of gas. These will create a foamy sputtering first pour of every drinking session. If your beer is coming out too fast, creating foam, you need longer or smaller diameter beer lines. Unfortunately there's no one length that works for everyone. The warmer the beer is, or the more carbonated, the slower the pour needs to be to prevent foaming. People keeping the beer very cold (<39°) and with moderate carb levels can often get by with 4-6' of 3/16" ID beer line. People serving warmer, in the 40-42° range often find they need 10' long 3/16" ID lines.

Here's a spreadsheet you can use to determine what length of line you need for a specific pour speed. I'd shoot for at least a 10 sec pint fill time, and longer if you're going to be serving the beer warmer or using higher carb levels.
https://docs.google.com/spreadsheet/ccc?key=0ApGb-vIKLq7FdGtzN3BrY2xZSldORzQ2bHVVX0hzaEE#gid=0

Two things to keep in mind. There's no disadvantage to extra long lines other than a slightly slower pour, and it's much easier to trim a few feet off of a line that's too long than it is to buy a longer line to replace one that's too short.

Ummm.... Awesome. I couldn't have asked for a better response.

Much appreciated dude!

 

[dstranger99]

I saw a Northern Brewer youtube vid where he force carbed at 20 for 3 days, then set it to 12 ...........

 

[chickypad]

I saw a Northern Brewer youtube vid where he force carbed at 20 for 3 days, then set it to 12 ...........

That is burst carbing, where you force carbonate for a short time at a pressure higher than your target equilibrium pressure, then turn it down to the actual pressure you need for the carb level you want. The idea is to get to your target carb level faster, but the danger is overshooting and overcarbing your beer.