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Flat soda but foams when dispensing

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Danimal86

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I've been making diet coke using soda syrup (4:1 water to syrup).
I've got a carbonating keg lid on the Sankey, but I don't have lasting carbonation. It foams nicely when poured, but it doesn't last. Soda is basically flat after dispensed.
I'm pushing about 30psi on a perlic faucet using about 3' of line in a kegerator

Any ideas how to make some longer lasting carbonation?
 
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RPh_Guy

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I'm really not the right person to answer, but it's obvious your line is waaay too short (and make sure it's chilled). There are serving line length calculators out there to help determine the correct length needed based on psi, etc.

Lots of other threads about this.

Hope this helps.
 

bracconiere

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lol 3' at 30PSI? you didn't add enough a's to that "waaay"......if he mentioned 3' though sounds like he's aware of the importance of line length?

i use 12-13' of 1/4" at 8psi......i was going to do the leg work, but the in house brewer's friend doesn't have a calc for line length.....google tells me 1/4" has 0.65 lbs per foot resistance.....
 
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Danimal86

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I'm really not the right person to answer, but it's obvious your line is waaay too short (and make sure it's chilled). There are serving line length calculators out there to help determine the correct length needed based on psi, etc.

Lots of other threads about this.

Hope this helps.
Thanks! I think i under estimated the length, its around 5' but it looks like its still too short. I had been pre-chilling the soda before i carbonated. This setup i was using for homebrew and it was working fine, but i've gotten away from homebrewing so i converted it to soda.
Using the formula: L = (P -(H x .5) – 1 ) / R i'm getting some long tubing lines. 30-(2x.5)-1)-1/.7 =40' of 1/4". The same calc with 3/16 gives me about 10' Not 100% sure on my beer line ID (not printed on the line). Looks like either way i'll go with 3/16
lol 3' at 30PSI? you didn't add enough a's to that "waaay"......if he mentioned 3' though sounds like he's aware of the importance of line length?

i use 12-13' of 1/4" at 8psi......i was going to do the leg work, but the in house brewer's friend doesn't have a calc for line length.....google tells me 1/4" has 0.65 lbs per foot resistance.....
Thanks. I'll grab some more line and swap it out (probably good to swap out the old line anyways).
 

bleme

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EVABarrier is some of the best line available right now and the 4mm allows for relatively short lines. It would be easier if you also switched to John Guest/DuoTight fittings, but it's not required.

 
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Danimal86

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This is what you're looking for:
Proper hose length - Mike Soltys
I think i'll have to end up dropping my pressure down from 30 to 20 or 25 to get a reasonable tubing length. I'm going to grab a 20' roll of 3/16 on my lunch and i'll just throw it all on and see how it does, worst case i'll just cut it down till its just right.
It still boggles my mind that a longer tube length would add more carbonation.
 
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Danimal86

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EVABarrier is some of the best line available right now and the 4mm allows for relatively short lines. It would be easier if you also switched to John Guest/DuoTight fittings, but it's not required.

Thats some nice looking tubing. Cheap too!
i haven't seen that style of fittings before. I'm still rocking the old school barbed fittings with a hose clamp.
 

IslandLizard

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I think i'll have to end up dropping my pressure down from 30 to 20 or 25 to get a reasonable tubing length. I'm going to grab a 20' roll of 3/16 on my lunch and i'll just throw it all on and see how it does, worst case i'll just cut it down till its just right.
It still boggles my mind that a longer tube length would add more carbonation.
As @bleme pointed out above, in Post # 6, using EVA Barrier line is a much better alternative.
That line can be much shorter, is truly Oxygen tight, and much, much easier to clean than vinyl line. Especially when changing out soda flavors.
 
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Danimal86

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Does anyone know if the same tubing length applies to nitro lines? My other tap is a cold brew on nitro and a stout faucet. I do get a nice creamy cascading bubbles. I'd have to double check, but i think i'm probably around 50psi for the nitro.
 
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Danimal86

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As @bleme pointed out above, in Post # 6, using EVA Barrier line is a much better alternative.
That line can be much shorter, is truly Oxygen tight, and much, much easier to clean than vinyl line. Especially when changing out soda flavors.
running the calculator with a 4mm ID drops the length down to 7'. How does it do as far as fitting over a barbed fitting?
 
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Danimal86

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Longer (and colder) lines don't add more carbonation. They prevent existing carbonation from coming out of solution due to the extra resistance it has.
I'm excited to see the results! I wonder if its going to be over carb'd...
 

IslandLizard

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running the calculator with a 4mm ID drops the length down to 7'. How does it do as far as fitting over a barbed fitting?
With a little heat applied (hot water) it should slide over 3/16" barbs. 1/4" barbs may take some extra work and effort.
Or replace barbed fittings with MFL ones and get MFL to push-fit adapters.
 

doug293cz

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I think i'll have to end up dropping my pressure down from 30 to 20 or 25 to get a reasonable tubing length. I'm going to grab a 20' roll of 3/16 on my lunch and i'll just throw it all on and see how it does, worst case i'll just cut it down till its just right.
It still boggles my mind that a longer tube length would add more carbonation.
The longer tubing does not "add" any carbonation. It prevents the carbonation from escaping during the pour, leaving more in the glass. Any foam you get during pouring is carbonation escaping from the beverage. The more foam, the less carbonation in the glass.

To minimize foaming, you want the "internal" pressure of the liquid to be close to zero when it leaves the tap. The higher the pressure of the liquid at the tap exit, the more foaming you get. The beverage line has internal flow resistance that drops the pressure as you move alone the line. The longer the line, the more the pressure drop. Line is characterized by a psi/ft pressure drop, so double the line length doubles the pressure drop. The psi/ft drop depends on the internal cross sectional area of the line, which increases as the square of the internal diameter, so ID is an extremely important parameter for line length. Different line materials also have different amounts of wall friction, which affects the psi/ft rating.

3/16" ID vinyl line has a resistance rating of about 1 psi/ft (be careful there are a lot of sources, and line length calculators, on the internet that think the resistance is about 3 psi/ft. and these will give you grief.) So, your 30 psi CO2 pressure would need somewhere around 30' of 3/16" line to get low foam pours. The 4 mm ID EVA barrier line has a significantly higher flow resistance per ft than 3/16" vinyl, so you can use shorter line lengths when using this tubing.

Brew on :mug:
 
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Danimal86

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The longer tubing does not "add" any carbonation. It prevents the carbonation from escaping during the pour, leaving more in the glass. Any foam you get during pouring is carbonation escaping from the beverage. The more foam, the less carbonation in the glass.

To minimize foaming, you want the "internal" pressure of the liquid to be close to zero when it leaves the tap. The higher the pressure of the liquid at the tap exit, the more foaming you get. The beverage line has internal flow resistance that drops the pressure as you move alone the line. The longer the line, the more the pressure drop. Line is characterized by a psi/ft pressure drop, so double the line length doubles the pressure drop. The psi/ft drop depends on the internal cross sectional area of the line, which increases as the square of the internal diameter, so ID is an extremely important parameter for line length. Different line materials also have different amounts of wall friction, which affects the psi/ft rating.

3/16" ID vinyl line has a resistance rating of about 1 psi/ft (be careful there are a lot of sources, and line length calculators, on the internet that think the resistance is about 3 psi/ft. and these will give you grief.) So, your 30 psi CO2 pressure would need somewhere around 30' of 3/16" line to get low foam pours. The 4 mm ID EVA barrier line has a significantly higher flow resistance per ft than 3/16" vinyl, so you can use shorter line lengths when using this tubing.

Brew on :mug:
Thanks for all the info. I went out and got 20' of food grade 3/16" tubing. I'll give that a try, and if it fixes my problem, i'll order the 4mm stuff. i dont want 20' of extra tubing hanging out in the kegerator.

if i lowered my pressure to 20psi, it should have a perfect pour?
 
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Danimal86

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So i just threw on 20 feet of 3/16 tubing. what a pain in the ass.
First of all, i have a double tower, and of course the 90deg piece was over the other faucet, so both had to be loosened. I didn't have the specialty wrench to loosen the nut on the back of the shank, so i pulled out just about every wrench/pliers i had. couldn't get channel locks or a crescent wrench in there....ended up with some needle nose vise grips. cut my hand on the razor sharp top of the tower.
it was a really snug fit on the barbed fittings. the shank wasn't too bad, but the ball lock, i had to dip the tube in warm water to get it over.

i poured a glass and the improvement was noticeable. Defiantly less violent of a pour, and an improvement of lasting carbonation, but not perfect. i'm going to up the psi a little to maybe 33 and see what happens. if that doesn't help, maybe i'll shorten the line by 4'.

I'll keep updating. Thanks everyone for the help/advice.
 

doug293cz

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So i just threw on 20 feet of 3/16 tubing. what a pain in the ass.
First of all, i have a double tower, and of course the 90deg piece was over the other faucet, so both had to be loosened. I didn't have the specialty wrench to loosen the nut on the back of the shank, so i pulled out just about every wrench/pliers i had. couldn't get channel locks or a crescent wrench in there....ended up with some needle nose vise grips. cut my hand on the razor sharp top of the tower.
it was a really snug fit on the barbed fittings. the shank wasn't too bad, but the ball lock, i had to dip the tube in warm water to get it over.

i poured a glass and the improvement was noticeable. Defiantly less violent of a pour, and an improvement of lasting carbonation, but not perfect. i'm going to up the psi a little to maybe 33 and see what happens. if that doesn't help, maybe i'll shorten the line by 4'.

I'll keep updating. Thanks everyone for the help/advice.
Raising the pressure or shortening the line won't help. You'll be going the wrong direction.

Brew on :mug:
 

Yooper

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I'm pushing about 30psi on a perlic faucet using about 3' of line in a kegerator
As was mentioned, that's about 27' too short.

I think i'll have to end up dropping my pressure down from 30 to 20 or 25 to get a reasonable tubing length. I'm going to grab a 20' roll of 3/16 on my lunch and i'll just throw it all on and see how it does, worst case i'll just cut it down till its just right.
It still boggles my mind that a longer tube length would add more carbonation.
the idea isn't to cut your pressure down to get equilibrium; the idea is to increase your restriction (the tubing) to preserve your carbonation level.

Thanks for all the info. I went out and got 20' of food grade 3/16" tubing. I'll give that a try, and if it fixes my problem, i'll order the 4mm stuff. i dont want 20' of extra tubing hanging out in the kegerator.

if i lowered my pressure to 20psi, it should have a perfect pour?
I have 28' of 3/16" rigid tubing on my 30 psi sparkling water, and it's great! The whole idea is to achieve equilibruim to get a good carbonation level and a good pour.
 
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Danimal86

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I have 28' of 3/16" rigid tubing on my 30 psi sparkling water, and it's great! The whole idea is to achieve equilibruim to get a good carbonation level and a good pour.
Thanks! I'm going to order the 39' roll of that 4mm tubing. I dont like having 20 feet of tube coiled up behind my keg. According the calculator 11 feet of the 4mm tubing should do the trick.

Does anyone know what if you have longer than needed tubing run? Just have a slower pour?
 
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Danimal86

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I was thinking that i may add an extra foot or two, just to be on the safe side.
Anyone know if that 4mm EVABarrier tubing is flexible at all? Using the 3/16 tube on the barbs was a little bit of a chore.
i'm not sure if this would work on my existing shank
I have the screw on style ball lock for that keg, i guess i could get one of these?
 

doug293cz

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I was thinking that i may add an extra foot or two, just to be on the safe side.
...
Yup, you can always shorten the lines if the pour is too slow, but you can't lengthen them if the pour is too foamy. A good target is 10 seconds to pour a pint. Once you have the DuoTight fittings, it's pretty easy to adjust line lengths, as you don't need to deal with clamps or barbs.

Brew on :mug:
 
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Danimal86

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Yup, you can always shorten the lines if the pour is too slow, but you can't lengthen them if the pour is too foamy. A good target is 10 seconds to pour a pint. Once you have the DuoTight fittings, it's pretty easy to adjust line lengths, as you don't need to deal with clamps or barbs.

Brew on :mug:
Good to know. I just ordered a roll of that 4mm tubing, some fittings, and some hardware to relocate the gas tanks outside the kegerator (morebeer got me for $150). Hopefully this will solve the problem.
 
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Danimal86

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I got all the equipment from morebeer. I put 14' of 4mm tube (went a little longer, so i could just trim it back). I used the duotight fittings on both the shank and the ball lock side. My first few pours seem to kinda bubble/gurgle at the faucet, and not much lasting carbonation. Looking at the line inside the kegerator, i dont see any gas bubbles in the line.

Any ideas? Maybe i just need to let the lines cool down a bit?
 
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