Beer Line & Resistance

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facter

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hi all

i would like to add some more beer line, i am currently unable to put any higher carbed beer through my lines as it ends up just as froth .. i have about an extra few meters for each line.

my question is, the extra line i have is smaller than the other line already attached tot he tap - will this cause a problem if i splice it on? I cant remember if big to small is bad, or if small to big is bad ...

cheers
 
Hey Facter,

Im no expert on beer lines, however being a civil engnineer I do know a bit about fluid mechanics. If your getting froth out the end of your lines it is because the pressure is too high. If you have long lines your friction losses will be high and you will need high pressures to get the beer to the end. So reduce the pressure on the CO2 or increase the size of the pipe at a constant pressure.
So to answer your question, putting more meters on will increase the skin friction and force required to push the beer. if you put on a smaller line and keep the same C02 pressure the pressure in this pipe will increase futher which means more foaming.... It is likely however that you will need to increase the pressure for the added distance and this will further exacerbate the foaming. So go for a bigger diameter to reduce the pressure in the pipe....

Hope that helps
 
I would think that if you are splicing, then going from large to small would be better as this would tend to increase the resistance and slow the flow down, rather than expanding the area and having less resistance.

That being said, why would you not just use one piece of line and not have a splice to worry about?

I ran mine with longer line than the wiki xl file said to, even though it is set to the correct kpa to gas my beer to 2.5 volumes. It seemed to slow the flow down nicely and now the beer pours with the right balance between head and gas.

Just my two cents worth.

Crundle
 
HI Crundle,

ur right it would increase the resistance and slow down the flow. however as the resistance is increased the C02 pushing the beer goes into solution and causes it to foam when it comes out the other end.
The idea with larger pipes is that at a constant gas pressure you get a higher driving force. With smaller pipes you need to increase the gas pressure to get teh same driving force to overcome resistance. high pressures and pushing beer is bad, i think?! If your beer is already foaming then u want to do what u can to decrease the pressure but increase the driving force for the added length.


Cheers
 
unfortuantly i cant use one line, as that would involve taking the entire assembly apart to replave it, and time is a factor ... been way too busy today.


this is from the wiki

"For most homebrewers, we are generally talking about fairly short distances, so it probably makes sense to choose nice thin beer line as that will give us more resistance per metre than larger line."

So we want something with more resistance .. which means small to big should be better, as this would start high, then drop a bit lower?



I swear i talked to Ross about this a few months ago, and this was the route to go, but maybe im confused here.


Oh well, it cant bve worse than i already have, which means pouring a beer and waiting five minutes for it to settle down haha
 
yup... i wouldnt go any smaller as the increase in resistance will cause the beer to foam like a b1tch...
go bigger and the worst that can happen is that it be really slow to come out (however it may not get there at all, but should with only a couple of meters extra).....
Either way mate u loose! splice on small and wait for ages for it to settle, splice on bigger and wait for it to get there.... whats worse! ;P
 
When transferring a carbonated product, when you go from a small diameter to a larger diameter, there is a corresponding decrease in pressure and gas comes out of solution. So avoid in your splice going from small to large diameter tube.
 
hmm. bugger.


but wouldnt the extra line length mitigate that anyways?




well, its already been spliced.. al i had on hand! Guess ill have to get some thicker stuff.

Well, ill test this anyways, im dying for a beer.
 
What about the taps that connect straight onto a corny keg without lines? I got one in the USA, and was hoping to use it to serve my weizens next weekend - am I just gonna get foam? I primed at 8g sugar per Litre, will this just net me glasses of foam? Can I put a length of hose on the end of the tap to increase resistance, or is this just silly talk?
Trent
 
hey shunty - i read a fair bit of that, but there wasnt anything relevant to my question - thanks though :)
 
I had the problem of the beer line length.

I would get the carb level i wanted and have it at equalibrium (oooo big word probably spelt wrong) with the pouring pressure but the beer came out of the tap too fast and caused lots of froth.

I was running 1 meter of 4mm ID line in my fridge.

I put 2 meters in and its great.

I can now have a higher carb level and it poures slower. meaning it doesnt froth as much when it hits the glass.

cheers
 
okay well, i just forced carbed my two kegs and attached them ...

Worked like a charm - infinitely better than before - it does pour a little slow, i have it on about 70kph or so, and both beers are carbed at about 150 ...but if I turn it up to around 90 it pours better, just a little bit more froth - but its not pouring an entire jug of foam anymore, so im pretty happy about that!


Looks like the small to big didnt cause many problems at all - im not sure how long the length was that ross supplied me with with the font, i think maybe two or three meters, but adding that extra two meters spliced seems to have done the trick - its not perfect, but hell, now it pours instantly and rather nice.


Just in time for my housemates birthday party tomorrow night hehe
 
Good to hear that it worked OK for you, I guess everyone has their point of view on line length, I can only say what worked for me but I have only just started with kegs. :party:

Been playing with pressures in my setup to see what works best, for me serving pressure on 80kpa, and 2m length of line works great, decent head on the beer and bubbles right to the end of the glass - the only problem is trying to avoid the temptation to sample all the time, its just so convenient having beer on tap - I don't know how I managed without this setup

Crundle :beer:
 
Hey guys,

Glad it worked out... at the end of the day we can all sit here and crap on about the mathematics of fluid flow but at the end of the day, its quicker to just try it and see if it works!

Time for me to change professions! :p

enjoy!
 
What about the taps that connect straight onto a corny keg without lines? I got one in the USA, and was hoping to use it to serve my weizens next weekend - am I just gonna get foam? I primed at 8g sugar per Litre, will this just net me glasses of foam? Can I put a length of hose on the end of the tap to increase resistance, or is this just silly talk?
Trent


Trent,

I'm pretty sure with those puppies you have to drop your keg pressure right down to serve out of them. You carbonate at whatever temperature and pressure is right to give you the volumes of dissolved C02 you want, but when you are serving it you will have to vent the keg a bit and run it at a much lower pressure. Or glasses full of foam it will be...

But it should be fine if you just drop the pressure till it pours ok. Then if you don't finish your keg before bedtime... you gas it back up to the carbonating pressure so it doesn't go flat overnight.

Thats why its great to have a "balanced" keg system ... enough line between keg and tap, so that the line provides enough resistance to slow the beer down as it leaves the tap.... but the pressure can stay at the right level for carbonation. Then you don't have to muck about changing pressures all the time when you just want to pour a beer.

For "normally" carbonated beers at about 2-2.5 volumes of dissolved C02... around 2.5 meters of 5mm ID line is about right... for higher carbed beers like your weizen, you need even more line. I'm about to install some JG quick disconnect fittings on my lines, so that I can just insert a meter or so extra when I want a more highly carbed beer on tap.

There are calculators around to help you work out what you need. But with the tap connected directly to the cornie ... your jst going ot have to vent some pressure.

Thirsty
 
Thanks for that Thirsty
Just what I was after. I will see how it goes, and vent it as necessary.
All the best
Trent
 
yup... i wouldnt go any smaller as the increase in resistance will cause the beer to foam like a b1tch...
go bigger and the worst that can happen is that it be really slow to come out (however it may not get there at all, but should with only a couple of meters extra).....
Either way mate u loose! splice on small and wait for ages for it to settle, splice on bigger and wait for it to get there.... whats worse! ;P


Sorry, this is wrong for beer lines - The line needs to stay the same or get narrower, from keg to font, for best performance.
The beer won't foam more if you drop the line diameter, as it's already pouring too fast. Increasing line length or narrowing the line will increase resistance & slow the pour, creating less foam.
The pouring pressure is not being increased, so no extra CO2 is going to be forced into the solution.

Cheers Ross
 
For "normally" carbonated beers at about 2-2.5 volumes of dissolved C02... around 2.5 meters of 5mm ID line is about right... for higher carbed beers like your weizen, you need even more line. I'm about to install some JG quick disconnect fittings on my lines, so that I can just insert a meter or so extra when I want a more highly carbed beer on tap.

Thirsty

Yes, the JG fittings make adjusting line length a breeze :super:


cheers Ross
 
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