Correct Dispensing Pressure?

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hellbender

hellbender

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If I do the math to balance the dispensing of my 2.5 Gal corny keg out of my fridge, I come up with about 10 psi. This is using about 4' of 3/16" and a picnic tap. The instructions that came with the keg say dispense at 3-5 psi. Which is correct?
 
10 psi sounds about right for a 4' hose. I'd go for a 6' hose with 12-14psi myself. I guess it depends on if you are carbonating your own stuff or just dispensing carbonated beer. 3-5psi will get the beer out, but it will be flat if its not already carbed up.
 
Hellbender,
You don't change your pressure to match your tubing ID and length. It's the other way around. You decide how carbonated you want your beer and based on the temp of the fridge you set the pressure to get you there. Once you know the pressure, you size your tubing so it doesn't dispense foam or dribble out. This can be anything between 3-10 feet. So, you probably wonder how you go about changing the tubing length all the time. You don't have to, if you make it too long, it just pours a little slow. If you make it too short you get a cup of foam. What's wrong with a slow pour? Nothing. 10 feet it is. It works great from 10-20i (that's an English Bitter up to a Wheat for me)
 
Bobby_M said:
Hellbender,
You don't change your pressure to match your tubing ID and length. It's the other way around. You decide how carbonated you want your beer and based on the temp of the fridge you set the pressure to get you there. Once you know the pressure, you size your tubing so it doesn't dispense foam or dribble out. This can be anything between 3-10 feet. So, you probably wonder how you go about changing the tubing length all the time. You don't have to, if you make it too long, it just pours a little slow. If you make it too short you get a cup of foam. What's wrong with a slow pour? Nothing. 10 feet it is. It works great from 10-20i (that's an English Bitter up to a Wheat for me)
Click to expand...

I understand all that. What I don't understand is why the keg supplier figures (and instructs) that the beer should be dispensed at 3-5 psi. for a keg with 4' of 3/16" tubing when any reasonable calculation would indicate otherwise. Any ideas?
 
I have no idea. There's a shrinking camp of people who ALWAYS drop pressure to dispense their kegs and many of them claim they do not lose carbonation even if they leave it there indefinitely. Those folks don't have a basic grasp of physics IMHO, but if the beer pours and they like it, great.

I hate the idea of changing my pressures depending on whether I'm serving or storing, etc. I set the pressure to what I want the beer carbed at and I call it a day. It stays there until the keg is empty.
 
I've moved over to Bobby's camp on this one.

I just swapped out my measly 4 feet of hose in my Sanyo (so dictated by doing that silly math thing) for an 8' piece.

Pressure is now set at 10PSI and the beer flows slow and smooth. No foaming. Before, I'd have to purge the keg of excess pressure and dial down to 4 or 5 PSI.

Whatever the math tells you to do...ad 3 or 4 feet and then dial up the PSI to your liking.
 
+1 on Bobby's camp. The cobra tap will have a bit less resistance than a faucet and shank, and there won't be the added resistance of height to the faucet. This is probably why they say to lower the psi for dispensing. However, if you do the math, you don't really lose that much resistance. Also, your beer will have more vols of CO2 than 3-5psi can keep up with which will create a gradual loss in carbonation over time.

Stick to Bobby's camp on this and you will be happier.
 
It looks like I need more line, as I am pumping a lot of foam if I don't do the purge and trickle out routine. A little bit of a tangent here. How do you carbonate different beers to different volumes? Do you have to do a different regulator on each keg?
 
Matt Foley said:
It looks like I need more line, as I am pumping a lot of foam if I don't do the purge and trickle out routine. A little bit of a tangent here. How do you carbonate different beers to different volumes? Do you have to do a different regulator on each keg?
Click to expand...

The short answer is yes. The practical reality is that many beers are carbonated at about the same level so you don't necessarily have to have 4 regulators for a 4 keg kegerator.

GT
 
If you are using a draft tower, foam may also becoming from the tower being too warm. If the beer warms up too much, the CO2 in suspension will come out of the beer causing foam.
 
Well, I got my portable draft system set up. (2.5 Gal keg, 8' of 3/16 ID vinyl beer line) Slow carbed the brew at 12psi for about 9 days. I'm thinking I can crank it out at 12psi with that much beer line. Nope . . .just a trip into foam land. After a little experimentation I finally got a good pour at 5 psi. WTF? I am glad I got got a good pour but who could have predicted an appropriate dispensing pressure?
 
The beer was great . . . . just wish I had a better handle on dispensing.:drunk:





hellbender said:
Well, I got my portable draft system set up. (2.5 Gal keg, 8' of 3/16 ID vinyl beer line) Slow carbed the brew at 12psi for about 9 days. I'm thinking I can crank it out at 12psi with that much beer line. Nope . . .just a trip into foam land. After a little experimentation I finally got a good pour at 5 psi. WTF? I am glad I got got a good pour but who could have predicted an appropriate dispensing pressure?
Click to expand...
 
Are the lines running through anything cold? What kind of portable system is it (jockey box, cold plate etc...). If it's just a line with a cobra tap, and you're serving this college style, it may require a lower psi do to less resistance. A faucet and shank will ad more resistance. Temperature is critical though. Is you're beer cold? If you're beer isn't at the correct temp you are going to have issues. I am betting it's a temperature issue.
 
Bobby_M said:
Hellbender,
You don't change your pressure to match your tubing ID and length. It's the other way around. You decide how carbonated you want your beer and based on the temp of the fridge you set the pressure to get you there. Once you know the pressure, you size your tubing so it doesn't dispense foam or dribble out. This can be anything between 3-10 feet. So, you probably wonder how you go about changing the tubing length all the time. You don't have to, if you make it too long, it just pours a little slow. If you make it too short you get a cup of foam. What's wrong with a slow pour? Nothing. 10 feet it is. It works great from 10-20i (that's an English Bitter up to a Wheat for me)
Click to expand...
Are you making a new beer line for each beer? Or do you just use the same pressure/temp (i.e. volumes co2) for each beer?
 
The keg is immersed in ice with the beer line running on top but not in the ice. The whole mess is contained in a closed Igloo cooler. The beer was quite cold. The keg spent 9 days in a 36 Deg fridge. I am using a shank and faucet which penetrates the sidewall of the picnic cooler. Perhaps you are right that the excessive foam at higher dispensing pressure may be caused by having 8' of beer line not actually in contact with the ice.

McSwiggin' said:
Are the lines running through anything cold? What kind of portable system is it (jockey box, cold plate etc...). If it's just a line with a cobra tap, and you're serving this college style, it may require a lower psi do to less resistance. A faucet and shank will ad more resistance. Temperature is critical though. Is you're beer cold? If you're beer isn't at the correct temp you are going to have issues. I am betting it's a temperature issue.
Click to expand...
 
Baron ken said:
Are you making a new beer line for each beer? Or do you just use the same pressure/temp (i.e. volumes co2) for each beer?
Click to expand...

This is the first time I have used thuis setup. I was actually thinking that 8' of 3/16 beer line was a bit excessive at 12 psi but I wanted to err on the side of caution since I didn't want too much foam and don't mind a slow pour. I was shocked that with this much line and a shank and faucet, that I would have to dial it down so much.
 
hellbender said:
This is the first time I have used thuis setup. I was actually thinking that 8' of 3/16 beer line was a bit excessive at 12 psi .
Click to expand...
Edit - Self corrected - my fractions never were that good. 3/16th is the way to go.

No expert, but if I remember correctly with 3/16th line you would need around 20 feet or more to drop the pressure. If you used 5/16th you could get away with 11 to 13 lbs and 6 feet, depending on the distance up from the k:Deg to spigot / faucet. You could see if you could put in a 5/16th choke point before the faucet to help drop the pressure if you don't have access to 5/16th beer line.
 

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