Beer line length / balancing

[Paul Cannell]

Just got a keg set up and just about a carb up my first lot. After much research I have decided that I will set my pressure to 10psi and leave it to carbonate in the fridge for a week at about 2 or 3 degrees.

I have some questions about beer line length and co2 line length. It seems there is quite a science to this and I need some help determining lengths. I have about 3m of line (I'm not entirely sure what daiamata) and I plan to use this for beer and co2 line. The reason I'm having issues working out line length is because I will be using a picnic tap and most formular seem to require a height difference between the top of the keg an the tap. I'll just have my entire setup siting in the fridge and the tap will most likely sit on the bottom at the base of the keg but will be lifted up when poured from.

Can you see my conndrum? Any suggestions?

Also is there any requirements for co2 line length? The co2 bottle will be sitting right next to the keg in the fridge.

[Tilt]

I'm having a few challenges in this area at the moment too.

Having seen a few different guides to calculating the right line length I've tried each of them and still haven't sorted it out.

Using the calc tools mentioned in the BYO article Dougal mentioned I get I need 13.7 psi at 6 degrees for 2.5 volumes of carbonation.

I'm using 3/16" (4.75mm) ID beer line.  I've seen a few different values for resistance (ranging from 1.8 to 3 psi per foot).  

Taking into account tap and shank resistance and height of the tap above the centre of the keg I get a calculation of between 1.68 and 1.95 metres of line. 

Trying lengths in this range I got glasses of foam. 

Trying the less precise "10 feet of line" talked about on US forums I also get a glass of foam.

I've also tried constricting flow using a G clamp on the line.  No joy.

Other than using the choke line Druid suggested is there anything else to try?

BTW this Brew Strong podcast is a good reference too.

[Dougal]

Interesting. What did you set the dispensing overpressure at in that calculation? I find their numbers work for me, but their recommendation of 5psi can be a be a bit excessive when I turn up the psi on my lines balanced for 2.5 volumes. They do say you can step it back to 1.5-0.5 psi. What's the pour rate like?

[John H]

Hi Tilt

 

My spreadsheet for 8 Deg and 2.5Vol gave me 15.6psi and 1.5-1.6 m of 3/16 line. I doubled the line to 3m and put in a John Guest push-fit connecter so I could trim it shorter untill it worked. Ended up fine at 3m so have left it at 3m. My tap is quite cool - I had to cut back the lagging in the fridge to the steel and put in a timber backblock so a lot of my shank is exposed to the fridge side so stays quite cool. Does your foaming improve after the first pour? warm line/tap could be an issue?

 

My tap is a perlicks with 6" shank- not sure whether diff taps have different figures

 

My spreadsheet for 6Deg, 2.5Vol gives me the same pressure at 13.7psi and line length between 1.27-1.38m. The spreadsheet uses a figure of 2.7psi/foot 

[Marlo]

I use 12 ft of 3/16" beer line at about 14 PSI and it works great. However if you need more restriction you could try adding these to the diptubes (see pic). I sometimes use two or three of them in the diptube to increase the restriction for beers served at higher pressures.

[Tilt]

Thanks fellas,

Yeah I figured 5 psi was a quick pour to Dougal so I set it at 1psi

Good tip on the tap / line temp thing John - my lines all sit in the fridge at 6 degrees and the tap is cool but not cold.  Saying that, the foaming doesn't change after the second or third consecutive pour so I don't think tap temp is the issue.

Now having a go using the second set of formulae in the BYO article listed above (the manual beer line length/ balancing ones) I get another answer again compared with the spreadsheet calculators I've used. 

The figures I plugged in are:

Tap resistance = 2psi  (assuming this is right for perlicks)

Shank resistance = 1psi (assuming this is right for a 4" 5mm ID bore stainless shank)

Tap above keg = 1 foot = 0.5psi ........................................................Total fixed resistance = 3.5psi

Carbonation pressure = 13.7 psi

Serve pressure = 1 psi at the tap.

So by my reasoning I get

Beerline  resistance  = Carbonation pressure (13.7)  - Serve pressure (1) - fixed resistance (3.5) = 9.2psi

 

So to use the range of figures I've seen for 3/16" line resistance

....At 1.8 psi per foot resistance I'd need 5.1' or 156cm

....At 3 psi per foot resistance I'd need 3.1' or 94.6cm

So using the tools and advice floating about I've got anywhere between 94cm and 305cm

Like you John I reckon this backs up the  "calculate the figure and double it......or half it......aah fuck it just take a random guess and muck about til its right and you'll probably be closer"  approach!

Anyone know how to recognise the symptoms of a line thats too long? 

I'd guess the beer wouldn't really ever stop flowing but all the dissolved CO2 would come out of solution which would greatly increase the overall volume of gas plus liquid.  So it would still be a bunch of foam and appear to be pouring too fast - even though theoretically it'd be too slow becasue the lines too long??  What?

Righto - I'll try some shorter lengths tonight to see what that does.  Back to trial and error.

 

[Matt Smith]

I wouldn't think an extra long line would cause problems other than a painfully slow pour and no head formation. I think as long as your line is at the same temperature as the beer in the keg, and its smooth with no kinks or corners the co2 should stay in solution until it leaves the tap

[Tilt]

Thanks Matt - I wasn't sure.  What made me wonder was the statement from the BYO article (which is probably the most in depth in terms of diagnosing problems based on symptoms I've seen) which said:

"If the dispensing pressure is too low, the beer will pour too slowly and excessive foaming can result, to the point where little beer and mostly foam ends up in the glass"

I was thinking pressure being too low is analogous to the line being too long - but may be off beam.

I tried a 1.20m length last night and got a predicted v fast pour plus a bunch of suds.

Reckon I might have to give the choke line or diptube swizzle stick a go.

[Matt Smith]

Ah I missed the part where you said you have already tried 10 foot of line. That's interesting. Have you been playing with the regulator much? Whenever I vent my keg and drop the reg pressure to do some bottling or something, then reset afterwards I tend to have foaming issues for a couple days until it all balances out again. I think the pressure equilibrium or whatever the terminology is, is really sensitive. Just wondering if that might be contributing to your issue.

I run my fridge at about 5-6 degrees, 10 foot/ 3 meters of line and all is good. Although, I think my pressure is a touch lower, about 11.5 psi for about 2.3 volumes 

[Hamish Jones]

one thing I have been told which made absolutley no sense at all was to have a longer gas input line from regulator to keg, the guy believed but could not explain why it helped at all but thought it was to do with having a more even pressure during pour, just thought I'd chuck that in to murk up the waters some more,

on the calculations my system shouldn't pour beer at all, I use 1.5m of beer line (stock kit stuff) my taps are 3/4 ot the way up the keg, two different types of tap with different shank lentghs,

I carbonate at 12 PSI for about a week then start pouring at that pressure, about half way through the keg I get minor foaming so I drop pressure to about 8-10 PSI and chop the keg, ever since I have been doing it this way never had a problem beer, prior to that was about to pay a brewery guy to come out and sort it out for me,

[Dougal]

I tried a 1.20m length last night and got a predicted v fast pour plus a bunch of suds.

At the risk of being contradictory, could one factor that's causing your setup to fail be that the beer has to reach equilibrium at whatever pressure you set it at? And if it's overcarbonated it certainly won't matter what pressure you pour at- you'll still get glasses of foam. Do you get too much foam when you back off the pressure to just enough to push it out of the keg through a short hose with picnic tap for bottling? I'd leave it a few days to settle into whatever dispensing pressure you set.

I use the BYO calcs and about 4-5psi overpressure. From memory, on my system (6C keezer, perlicks, 4" shanks, pouring through a freezer collar about 1.5-2 feet above the keg centre), that equates to about 2.2 metres of 5mm ID line and about 15psi for 2.5 volumes of CO2 [I think].

[Hamish Jones]

I am with you on that, I had alsorts of trouble originally and it was due to over carbination, it wasn't until after I sat down one night and had a commercial beer that I realised I was over carbonating, since then its been heaven in a fridge

[Tilt]

I didn't think played with the reg pressure much over the last week lol.  However maybe more than I should have being new to this and keen to get things sorted now! :)

But maybe pressure stability is my problem. 

Saying that each time I've changed the line length I haven't changed the pressure on the reg - hoping to change only one variable at a time and see the effects

I don't think its overcarbed.  At a low serving pressure - say 5psi at the reg - I get normal amounts of foam but a slow pour.  As you say Dougal - if was still all foam then I figured that would tell me its overcarbed.

Buggared if I get the longer gas line suggestion either Hamish - FWIW the gas line is about 1m.  But something else to try...and any easily tried suggestion is welcome at the moment.  Hey what do you mean by chopping the keg?

So the message is Patience Grasshopper....after one last tweak to try the longer gas line idea I'll let it sit for a few days to settle out.  Cheers fellas - just as well I've got a few old school bottles in reserve!