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Old 09-11-2012, 07:05 PM   #1
grathan
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When you serve beer out of a keg at 3psi, and you have just forced carbonated at 30psi, Does the pressure back-feed into the co2 tank or does the regulator stop this?

 
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Old 09-11-2012, 07:15 PM   #2
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your tanks holding 500-800psi.

Simply put. no...when force carbing you had the liquid absorb about 10-15psi, backing it down to 3 will use pressure in keg instead of drawing from the tank. although if left at 3psi youll eventually have no push on your fluid and start loosing it out of solution

youll just have to adjust for pressure lost in the keg every couple of days(or hours depending on how fast you drink)
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Old 09-11-2012, 07:16 PM   #3
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Why are you serving at 3psi?? I would use this chart to figure out the pressure at temperature (for both carbonating AND serving). Also, how long did you have the keg at 30psi?? Normally, you equalize the pressure in the keg post carbonation to be at serving pressure so that you don't have any issues. You should also have lines long enough to serve the beer at the correct temperature, and pressure, without having a glass of foam.

As for the regulator, it should have a fitting that will prevent CO2/liquid from going into the body. Without knowing what you have for a regulator, and where you got it (or how it's set up) we cannot say (for certain) that you have one on it.
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Old 09-12-2012, 01:19 AM   #4
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If you don't have check valves on your gas lines you can get beer to back up into the gas lines. I have check valves in all my gas lines and highly recommend them.

 
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Old 09-12-2012, 01:23 AM   #5
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Quote:
Originally Posted by Gartywood View Post
If you don't have check valves on your gas lines you can get beer to back up into the gas lines. I have check valves in all my gas lines and highly recommend them.
Yep! If your beer is at 30 psi and the regulator isn't, you could get some back flow into your regulator.

Why you'd force carb a beer at 30 psi and serve at 2 psi, I'll never figure out. But I wouldn't even try it!
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Old 09-12-2012, 11:43 AM   #6
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Sorry, the numbers were only arbitrary. Just thinking back to the hassles I had a couple years ago when I tried to use kegs as I am getting ready to use them again.

SO once you get your co2 dissolved to proper volumes, as long as the serving psi stays above 3, none of the dissolved co2 will come out of solution?

 
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Old 09-12-2012, 11:56 AM   #7
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No, you would need ti carb to proper volume and serve at that pressure for it to not start losing pressure. Once you start serving your keg pressure will drop and will only be replaced by the psi the regulator is set to. So eventually your pressure will balance to whatever the regulator is set for. I.E. if you set to 30psi then drop regulator to 10psi for serving once the pressure in your keg drops below 30 it will continue to drop till it gets below 10 then will be replenished by the regulator to 10PSI.
if I'm wrong someone will correct me in sure.
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Old 09-12-2012, 12:48 PM   #8
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Quote:
Originally Posted by GilSwillBasementBrews View Post
No, you would need ti carb to proper volume and serve at that pressure for it to not start losing pressure. Once you start serving your keg pressure will drop and will only be replaced by the psi the regulator is set to. So eventually your pressure will balance to whatever the regulator is set for. I.E. if you set to 30psi then drop regulator to 10psi for serving once the pressure in your keg drops below 30 it will continue to drop till it gets below 10 then will be replenished by the regulator to 10PSI.
if I'm wrong someone will correct me in sure.
No, that's correct.

I've heard of people who have "carbonation pressure" and "serving pressure" but due to the physics behind it, it's destined to not work long term.

My kegerator is set at 12 psi at 40 degrees. I keep it there, and it works great all the time.

If I'm in a huge hurry for a new keg to be ready, I will set that one keg at 30 psi for 36 hours, then purge and put back to 12 psi with the others. That carbs it up faster, but any longer at 30 psi would mean it would be overcarbed.

In general, a balanced system won't ever need to be turned to a "serving pressure", unless doing something like using a Beergun to fill bottles or to transfer under c02 to a new keg.
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