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-   -   forced carb vs cast carb (http://www.homebrewtalk.com/f35/forced-carb-vs-cast-carb-48971/)

tgrier 12-24-2007 04:34 AM

forced carb vs cast carb
I have been reading a great deal on forced carb ... how much co2 per style of beer and at what temp and pressure is needed to hit that mark..

My question as a person who has done the sugar and keg and come back a week or so later ... and have a carbed keg...

If different styles of beer are better at different co2 levels.. it would seem that in cast conditioning that a different level of sugar would be required ... (more or less) to hit the desired co2.

It seems like most people here force carb. I am trying that for the first time with a hefe.
I have it @ 38f with 21lb of co2. What I am not finding is a chart that tells me how long do I leave it at this pressure and temp?

Any feedback would be great...


wild 12-24-2007 05:58 AM

Here's your Chart.

Good luck,

malkore 12-24-2007 02:00 PM

its basically always 10-14 to force carb. the beer can hold a LOT of CO2 in solution, so as long as your temperature is in the right range, the beer will absorb 21psi about the same rate as 10psi.

but at 21 psi, yer gonna need plenty of beer line to equalize the pressure, unless you want to turn off CO2 and vent the excess until you hit 10psi, then dispense...then remember to turn the gas back on at the end of the day.

there are other charts for balancing CO2 volumes to serving line length. I think you'll need something like 14-16feet.

Funkenjaeger 12-24-2007 03:31 PM


Originally Posted by malkore
its basically always 10-14 to force carb. the beer can hold a LOT of CO2 in solution, so as long as your temperature is in the right range, the beer will absorb 21psi about the same rate as 10psi.

That's not true, the higher the pressure the faster the beer will absorb CO2, which is exactly the reason that some people force carb by setting it to a higher pressure for a few days and then turning it back down to serving pressure. It's also why the "crank and shake" method of force carbing is done at around 30PSI instead of serving pressure. A couple minutes of shaking at 30PSI can get it fully carbed (and even overcarbed, if you're not careful), but the same amount of time shaking at 12PSI leaves it very flat still.

Tgrier, are you only at 21PSI to help fast carb it, or is that your actual target pressure based on carbonation tables? It looks like that would produce about 3.4 volumes of CO2 if left that way, which is very high. If that IS your target pressure, you're going to be dealing with headaches dispensing it, as malkore mentioned - either you'll need a LONG beer line, or you'll need to vent and drop the pressure each time you serve.

tgrier 12-24-2007 04:18 PM

Well... I am not necc trying to speed carb it.. I am just trying to do it the right way.

I looked at a couple of charts.
And it said that wheat beer should be carbed up to 3.4 area.

Then I looked at the temp and pressure.. and I read that it should be set to 21psi @ 38f.

I assumed that I would release the pressure and move it to serving pressure once the carb was done. What I did not read on the charts was the timeline how long to leave it @ 21psi @ 38f.

I would rather not speed up the process but rather learn the "right" way and get my system down.

The sugar carb method worked very well it took a little longer sometimes 2 weeks. but if the forcred carb method is going to take a week and I have to leave it hooked up... I might just stick with using sugar....

That is what I am looking for... a procedure to follow.

Funkenjaeger 12-24-2007 04:39 PM

Leaving it at the target pressure to slowly force carb can take 1-2 weeks. There's really no "rule" per se, you just leave it until the desired carb level is reached.

Also, if you are targeting 3.4 volumes, you can't just force carb it and then drop it down to a lower serving pressure permanently, or it will lose carbonation until it equalizes with the carb level determined by your serving pressure (again, use the tables)... If you want to serve below 21PSI, you have to drop the reg pressure, bleed the keg pressure, pour, and then crank the pressure back up to the storage pressure of 21PSI. I'm sure that will be a royal pain, which is why people balance their systems by choice of beer line length so they don't have to deal with that. Based on a flow resistance of 1.6psi/ft for 3/16"ID beer line, you're looking at about 14 feet of beer line if you want to carb and serve at 21PSI.

In my opinion, that's enough reason to not bother carbing my kegged hefe's so heavily, unless I already had a huge amount of beer line laying around.

malkore 12-24-2007 07:13 PM

yer right funken, it will carb faster at a higher psi. i guess i was less awake than I realized, cuz I knew that...I've DONE that on a keg (a few days at high psi to speed up carbing).

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