Beer Line Balancing - Different Line ID!

[-MG-]

I need help figuring out how to balance my kegging system. I currently have a keezer kept around 35 F. I keep the PSI around 10 right now. I have about 5' of 3/16 ID beer line that feeds into a glycol cooled trunk which is 5/16" ID. There is 14' of that going through a wall and changing again to about 5' of 3/16" beer line that goes right into the tower. My beer is pouring foamy then clear then foamy again, etc. I can see bubbles inside the keezer in the beer lines.

My beer is pouring at around 40 F in the glass without dumping any beer, but very foamy.

To summarize:

5' 3/16" line -> 14' 5/16" line -> 5' 3/16 line to faucet.
I would guess the lift is around 2-3' from center of keg to taps.

Can anyone help me on how to balance this multi line system? I would like to keep my trunk line since I already have it even though its a different size.

 

[-MG-]

I just did some math using the info here:

http://www.kegworks.com/blog/determine-right-pressure-for-your-draft-beer-system/

It looks like with rough math the PSI would need to be nearly 30 for me to be balanced with this line...

If I replaced the first 5' to 3/8" ID line that would lower the PSI requirement to around 17 which is more manageable, but still high.

I would have to turn temperature in the keezer up to around 41 and PSI of around 14 to be at 2.6 volumes. I suppose this is my best bet to try before having to junk the trunk line.

 

[sandyeggoxj]

Just run 5/16 from the kegs to the last section where you choke it to 3/16. Drop the glycol temp a bit and raise the keg temp to 40. If you can shorten the choke at the end you should be able to pour around 13-14 psi and at that carbonation you will maintain carb volumes.

 

[-MG-]

Just run 5/16 from the kegs to the last section where you choke it to 3/16. Drop the glycol temp a bit and raise the keg temp to 40. If you can shorten the choke at the end you should be able to pour around 13-14 psi and at that carbonation you will maintain carb volumes.

That's what I was thinking, except for the 3/8 side. I'll play around with this and that should fix my issues.

Thanks.

 

[sandyeggoxj]

I haven't built a system like this but it makes sense in my head. I do know that it is helpful to avoid changes in velocity.

 

[day_trippr]

I agree with running a large bore line from the kegs to a reducer made for the purpose of dropping down to a 3/16" ID choker. It'll be a hella lot easier to tune the choker length and you get rid that first transition that's likely causing a standing pressure drop that can't be great for maintaining carbonation...

Cheers!

 

[-MG-]

I'm letting the system even out now since I've increased the PSI and raised the temperature. Initially I saw a lot of bubbles still in my new 3/8 line and poured out a few glasses of foam. I went to look at it again and its vastly improved as far as bubbles in the line.

I'll test tonight to see how its looking. I was also able to reduce about 2.5' of the 3/16 line going right into the tap tower. I should only have now about 2-3' of 3/16 line total. The rest is 5/16 and 3/8.

 

[-MG-]

Well it didn't solve my problem.

When I kicked the PSI up to 14 I was pouring a full mug of foam in about 3 seconds, way too fast.

It's still going foam - clear - foam - clear

Temperature on first pour remains consistent around 40 F. So I know it's not temperature related.

It's interesting its pouring too fast when they math says that I should be fairly close to balanced. Ideas?

 

[sandyeggoxj]

Maybe back to the full length of choker?

 

[-MG-]

Maybe back to the full length of choker?

It's definitely worth trying, but the math for balancing doesn't make any sense.

But like I said at 14 PSI its pushing the beer way way too fast.

I'm trying to think of why I would see bubbles in the beer line and what that means.

 

[sandyeggoxj]

My jockey box is 24' of 1/4", 8' of 5/16" and 2' of 3/16". I see bubbles collect at the high points in the tubing but it doesn't affect the pour.

Have you tried different keg couplers or kegs? Same behavior? It could be a problem outside the tubing.

 

[-MG-]

My jockey box is 24' of 1/4", 8' of 5/16" and 2' of 3/16". I see bubbles collect at the high points in the tubing but it doesn't affect the pour.

Have you tried different keg couplers or kegs? Same behavior? It could be a problem outside the tubing.

They are all commercial kegs. Tank 7, Kona Longboard Lager, and Sam Adams all pour the same way. Only thing in common with all three is the PSI setting is through the same manifold and they share the same line sizes.

 

[sandyeggoxj]

Same sanke couplers? Or you have all three on tap at the same time so three couplers?

The "balancing equations" out there can be a good starting point but they have plenty of flaws. I'm wondering if it would be best to run 5/16 from the kegs to the choker instead of starting with 3/8. That 1/16" difference in ID could be the difference between foam and no foam.

Also, how is the line staying cold from the keg to the glycol line?

 

[-MG-]

Same sanke couplers? Or you have all three on tap at the same time so three couplers?

The "balancing equations" out there can be a good starting point but they have plenty of flaws. I'm wondering if it would be best to run 5/16 from the kegs to the choker instead of starting with 3/8. That 1/16" difference in ID could be the difference between foam and no foam.

Also, how is the line staying cold from the keg to the glycol line?

Three different couplers so all on tap at same time. That's possible and may be my next step to avoid any 'bottle neck' points. I've never been able to test the actual line inside of the trunk line, but it was bought from micromatic and same thing bars use. It has the glycol lines in the center of it making contact with all beer lines. I haven't insulated the connections right under the tap tower and the glycol lines even show a light coat of icing on them. I imagine when I insulate that goes away.

 

[sandyeggoxj]

Is it this stuff: http://www.micromatic.com/draft-keg-beer-edu/keg-beer-trunk-line-cid-1789.html

I bet that there is a bit of warming at each end of the trunk that is causing the foam. What happens if you pour 3 pints back to back? Does it get better with each pint?

 

[-MG-]

Is it this stuff: http://www.micromatic.com/draft-keg-beer-edu/keg-beer-trunk-line-cid-1789.html

I bet that there is a bit of warming at each end of the trunk that is causing the foam. What happens if you pour 3 pints back to back? Does it get better with each pint?

Yup that's it, but doesn't have the diamond plate outside, but same concept.

There is no difference in foam from back to back to back beers.

Also should note that the trunk line feed directly into the keezer that has fans in it so shouldn't have temperature issues on that end.

 

[barnaclebob]

You could try replacing the line in the keezer with 5/16 to avoid one of the changes in speed. What temp does your trunk line stay at. If you have 35 degree beer in the keezer but 40 degree beer in the cup then its getting heated somewhere.

 

[-MG-]

You could try replacing the line in the keezer with 5/16 to avoid one of the changes in speed. What temp does your trunk line stay at. If you have 35 degree beer in the keezer but 40 degree beer in the cup then its getting heated somewhere.

This most likely is my next thing to try. When I went to balance my system. I raised the keezer temp to 40 to account for the 14 PSI as to not go too far past 2.6 Volumes/CO2. Even with this change I'm pouring at 40 F still.

 

[-MG-]

I found this excel sheet which appears to be above my pay grade, but basically shows I have a pretty big disconnect from balance:

https://docs.google.com/a/dorm.org/...-vIKLq7FdGtzN3BrY2xZSldORzQ2bHVVX0hzaEE#gid=0

I'm playing around with the numbers on the second tab to see what PSI I can use.

Would be nice if I could account for my different line ID's.

EDIT: I took the averages of my beer line and estimated removing the 3/8 line and replacing with 15' of 3/16. When I do that and have 32' of total line. it says I can have a CO2 Pressure of 11.93. Which is doable for my system. I suppose this is my next step.

 

[JuanMoore]

Lots of misconceptions in this thread. Firstly, you want to determine your serving pressure based on the carbonation level and beer storage temperature, and then adjust other variables to get a good pour, not the other way around. The serving pressure always needs to match the equilibrium pressure of the carbonation level and temperature. If you lower the serving pressure below that level, CO2 will break out of solution in the lines and cause the first pour or two of every drinking session to be foamy, and eventually you'll start losing carbonation. If you raise the serving pressure above the equilibrium pressure, the carbonation level in the beer will increase quickly.

Most of what you've found on the web regarding "balancing" is very misleading, and the term itself is a misnomer IMO. There's no balancing going on when setting up a draft system, you simply need enough resistance in the line to slow the flow of beer down to prevent excessive CO2 from coming out of solution when the beer hits the glass. The warmer or more highly carbonated the beer is, the slower the pour needs to be. The calculators and equations you're using (with the sole exception of the excel sheet you found) are all designed to result in the same flow rate of 1 gal/min, which is too fast for a lot of situations.

You could have a 50' line and have no ill effects other than a slightly slower pour, so stop worrying about the "balanced" length/pressure. If you increase your pressure like you think the calculator is telling you to, you'll end up with a pour speed of 1 gal / min, which will be too fast for your temp, and you'll end up with severely overcarbed beer.

As others have mentioned, going back and forth between larger and smaller diameter line can cause issues. It's fine to step the size down as you go, but stepping back up is problematic. Splices and joints can also cause issues if there are sharp edges on the inside. I'd suggest using the same diameter through the trunk, and then step down to a 10' length of 3/16". If the slow is really slower than you can tolerate (unlikely) it's really easy to trim a few feet off.

The first order of business though is getting your serving pressure right. What is the carb level of the beer? How did you carb it? What's the current beer storage temp?

 

[JuanMoore]

And FWIW the excel sheet you found is really easy to use once you understand what it's for. It's for determining the line length to result in a desired flow rate (measured by the time it takes to fill a pint). So you input your serving pressure, line diameter, etc, choose a pint fill time (7 sec is ~1 gal/min, 10+ sec would be recommended for moderate carb levels and exit temps up to 40F, 12+ sec for higher temps/carb levels), and it tells you how long you need to make your line. Keep in mind that this is a minimum length, and there's no ill effects to going longer.

 

[-MG-]

The first order of business though is getting your serving pressure right. What is the carb level of the beer? How did you carb it? What's the current beer storage temp?

All my kegs are currently commercial beers. Boston Lager and Kona Longboard lager, both should be around 2.6 Volumes/Co2. The Keezer is setup at 40 F. I previously had it colder.

Can I average out the hose diameters? I only have the ability to add additional line inside the keezer between the coupler and the trunk line. I was using the excel sheet to find the PSI setting that is within reason and then set my keezer for the appropriate temperature.

If I average out my lines it comes to .242 in. I have 3 feet of rise to the tap height. Calculating this way tells me I need around 31' of line total. Does that math work out correctly? I just looked at trunk lines and noticed they really only come in 5/16 or bigger and it makes it difficult to balance without an unreasonable length of line.

Broken out like such:

15' 3/6 line -> 14' trunk like 5/16 (this can't change) -> 3' 3/6 Line going directly into the tower

 

[JuanMoore]

Since a diference in diameter results in an exponential change in line resistance, you can't simply average the diameters. Since the trunk line doesn't provide significant resistance at the flow rate you'll likely end up using, I'd just pretend it isn't there for your calculations.

Are you absolutely sure you can't engineer some way to have a small diameter choker at the faucet end of your line? You might be fine with it on the keg end, but the more potential areas causing foam you can eliminate the better. Trunk lines are typically used for conveying beer very long distances, and they're so large in diameter so that the resistance is minimized. Even when using them for 50-100' runs, they still design the systems to allow for a small diameter choker to be used at the faucet end.

Any particular reason you raised the temp other than the suggestion above? If not, I'd drop it back down. I prefer slightly warmer beer for drinking purposes, but the colder it is the easier it is to control foam issues, and a few degrees can make a huge difference.

And FWIW you should be around 13.5 psi for 2.6 vol and 40°. If you drop the temp to 38 you'd want it at 12 psi. At 36° you'd want 11 psi. Whatever temp you decide on, set the serving pressure to equal the equilibrium pressure at that temp and leave it there.

Another potential issue might be uneven cooling. Even if your exit temp is fine, if there are warm spots and cold spots on the journey from the keg to the faucet, it will cause problems. The symptoms you described sounds like either temperature issues or your serving pressure not matching the equilibrium pressure. The other much less likely cause is a bad seal in the coupler/spear allowing gas to enter the line as it pours. Does the foam issue get better if you pour 3-4 pints back to back? If so, then you can rule out a bad seal.

 

[-MG-]

Since a diference in diameter results in an exponential change in line resistance, you can't simply average the diameters. Since the trunk line doesn't provide significant resistance at the flow rate you'll likely end up using, I'd just pretend it isn't there for your calculations.

Are you absolutely sure you can't engineer some way to have a small diameter choker at the faucet end of your line? You might be fine with it on the keg end, but the more potential areas causing foam you can eliminate the better. Trunk lines are typically used for conveying beer very long distances, and they're so large in diameter so that the resistance is minimized. Even when using them for 50-100' runs, they still design the systems to allow for a small diameter choker to be used at the faucet end.

Any particular reason you raised the temp other than the suggestion above? If not, I'd drop it back down. I prefer slightly warmer beer for drinking purposes, but the colder it is the easier it is to control foam issues, and a few degrees can make a huge difference.

And FWIW you should be around 13.5 psi for 2.6 vol and 40°. If you drop the temp to 38 you'd want it at 12 psi. At 36° you'd want 11 psi. Whatever temp you decide on, set the serving pressure to equal the equilibrium pressure at that temp and leave it there.

Another potential issue might be uneven cooling. Even if your exit temp is fine, if there are warm spots and cold spots on the journey from the keg to the faucet, it will cause problems. The symptoms you described sounds like either temperature issues or your serving pressure not matching the equilibrium pressure. The other much less likely cause is a bad seal in the coupler/spear allowing gas to enter the line as it pours. Does the foam issue get better if you pour 3-4 pints back to back? If so, then you can rule out a bad seal.

There currently is a small diameter choke at the faucet by going back down to 3/16. That's the best I can do there. The foaming appears to be consistent whether 3 or 4 pints are poured. I can definitely take the temperature back down.

One interesting fact: When I changed CO2 tanks I forgot to put that plastic seal back in it and I came home to an empty C02 tank two days later. The funny thing was, that when the CO2 tank had a 3-4PSI on it. I was pouring near perfect pints. The only problem with that pressure setting is that I can't get cold enough to maintain volume.

In about an hour I'm going to head to the LHBS and pick up some 3/16 line. Based on your post. I can potentially ignore the trunk line and just use the excel to see what works. Based on my parameters using only 3/16 line, if I add around 12' of line that would give me a 12 sec fill time (I also prefer slower). I may just start at 20' and see what happens.

Thoughts? am I going the right direction?

 

[The_Bishop]

If you use a choker at the keg end, you're going to have a pressure drop when it hits the larger diameter line, and that'll knock the CO2 out of solution. The choker needs to be at the faucet end.

Edit: Got ninja'd.

How long is the choker line at the faucet? You need some length for the liquid to 'settle down' after a tubing diameter change.

The temperature of the run is a factor, too. The whole run needs to be cooled or you get what's happening to you, as well.

Second Edit: Read the first post again.

This is a huge problem:
5' 3/16" line -> 14' 5/16" line -> 5' 3/16 line to faucet

That initial transition from 3/16 to 5/16 isn't doing you any favors. I'll bet that is where the CO2 is getting knocked out of solution. There's a pressure drop at the transition, making co2 bubbles in your beer line.

 

[JuanMoore]

One interesting fact: When I changed CO2 tanks I forgot to put that plastic seal back in it and I came home to an empty C02 tank two days later. The funny thing was, that when the CO2 tank had a 3-4PSI on it. I was pouring near perfect pints. The only problem with that pressure setting is that I can't get cold enough to maintain volume.

This tells you everything you need to know to get a decent pour with your less than ideal situation. Due to the issues with the small -> large -> small line thing, you're gonna need a very slow flow to get a decent pour, which is why it worked ok at a very low pressure.

Use the excel sheet, set the pressure to 3.5 psi, and keep changing the pint fill time until the line length matches the total length of 3/16" ID line you had when that happened. Record that pint fill time. That pint fill time is what you need to input into the calculator with your actual serving pressure to get the length of 3/16" line you need to use to get the flow rate that you know works well. Make sense?

 

[-MG-]

This tells you everything you need to know to get a decent pour with your less than ideal situation. Due to the issues with the small -> large -> small line thing, you're gonna need a very slow flow to get a decent pour, which is why it worked ok at a very low pressure.

Use the excel sheet, set the pressure to 3.5 psi, and keep changing the pint fill time until the line length matches the total length of 3/16" ID line you had when that happened. Record that pint fill time. That pint fill time is what you need to input into the calculator with your actual serving pressure to get the length of 3/16" line you need to use to get the flow rate that you know works well. Make sense?

That does make sense and I can work with that. Is there any benefit to me using 5/16 line at the beginning so there is no choke at the beginning and there would still be a 3/16 choke at the end?

 

[The_Bishop]

That would work but you need to have a straight 5/16 line at the beginning; no couplers. Anything that disturbs/restricts flow is a potential CO2 breakout point.

 

[JuanMoore]

That does make sense and I can work with that. Is there any benefit to me using 5/16 line at the beginning so there is no choke at the beginning and there would still be a 3/16 choke at the end?

Yes, but I think you'll find that you'd need an absurdly long line to result in the required flow rate.

 

[-MG-]

Yes, but I think you'll find that you'd need an absurdly long line to result in the required flow rate.

Correct. I'll do some experimentation tonight and report back. I appreciate the insight. The interesting thing about the calculation you had me run for when the CO2 tank was about empty is that it didn't seem like it took 16 seconds to fill. It seemed like a comfortable 10 seconds.

 

[JuanMoore]

Correct. I'll do some experimentation tonight and report back. I appreciate the insight. The interesting thing about the calculation you had me run for when the CO2 tank was about empty is that it didn't seem like it took 16 seconds to fill. It seemed like a comfortable 10 seconds.

Most "pint" glasses here in the US are actually 12oz, not 16oz, which might be part of the difference in perception. I'm sure the trunk line slows things a little too, so it's probably slightly faster than 16 seconds.

 

[-MG-]

Ha.. so I get home and my tank is empty again... Time to redo the entire air system!

 

[-MG-]

Problem resolved.

I finally did find that the specs on the trunk line say the resistance is .1 lb per foot. So your point to basically act as if the trunk isn't there was correct.

Pours are a little slower than I like, but it's pouring a perfect head on all beers now.

 

[JuanMoore]

Problem resolved.

I finally did find that the specs on the trunk line say the resistance is .1 lb per foot. So your point to basically act as if the trunk isn't there was correct.

Pours are a little slower than I like, but it's pouring a perfect head on all beers now.

Glad to hear it's been resolved. In order to get a faster pour, you'd need to engineer a way to eliminate the large ID -> small ID -> large ID line issue.

I could have told you that line resistance figure, but it's not a constant, it's only valid for a flow rate of 1 gal/min. At your slower flow rate it's actually much less, which is the main reason I suggested ignoring the resistance from that section. The resistance increases by the square of the increase in fluid velocity, so if you cut your pour velocity in half, your line resistance would be 1/4 of what it was. This is why people need to increase their line lengths dramatically in order to reduce the pour speed just a little.