### Author Topic: serving pressure  (Read 3045 times)

#### jimrod

• Assistant Brewer
• Posts: 181
##### Re: serving pressure
« Reply #15 on: January 23, 2012, 02:21:02 AM »
no
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#### a10t2

• Official Poobah of No Life.
• Posts: 4333
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##### Re: serving pressure
« Reply #16 on: January 26, 2012, 01:42:28 PM »
The problem is that pressure drop due to the tubing isn't all there is in the system, and making that assumption gives results that are seriously wrong, like vendors saying the pressure drop is 2 psi/ft.

3/16" ID beverage line will drop ~0.7 psi/ft; 1/4" ~0.15 psi/ft. To that you have to add the pressure drops caused by the fittings in the system. For a typical keg/faucet arrangement that seems to be around 6 psi. So that's where the equation I posted earlier comes from. http://seanterrill.com/2011/11/11/a-more-accurate-approach-to-draft-system-balancing/

So yes, for 3/16" tubing you'd need ~12 ft. With 1/4" tubing you'd need ~60 ft. Obviously, the 1/4" stuff is only practical in a bar setting.

2 ft of vertical rise will drop another 0.9 psi, so that's a relatively minor concern. If you're running lines up a floor or something then it needs to be considered, though.
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#### boapiu

• Cellarman
• Posts: 90
• Palmetto Bay, FL
##### Re: serving pressure
« Reply #17 on: January 28, 2012, 02:12:43 PM »
all the formulas are well,and good but i would think that whatever works for you is what you should use. my kegs are at about 38* and the carbonation is 10-12 psi. i hooked a simple picnic party tap to 10 feet of 1/4" tubing from HD for about \$2.69. the beer is now serving quite excellently for my tastes with a nice carbonation and fine head. i also found the info in the draft quality manual to be very helpful as far as estimating the pressure drop per foot, etc. i like keeping it simple
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#### rgnlkngtylrbmbstk

• 1st Kit
• Posts: 18
##### Re: serving pressure
« Reply #18 on: January 30, 2012, 10:33:27 AM »
I've been having trouble with my serving pressure.
Did you get the pour you were looking for?
I have to say just increasing the resistance probably won't get what you're looking for. There's a sweet spot that keeps CO2 in solution throughout the serving line, and when the pressure drops below that you get "breakout" which will make your beer come out slow and foamy instead of fast and foamy. It can be maddening if you aren't aware of what's happening.

The tube on the end ought to be about 1/4" ID if I recall, which is bigger than your serving line, right? Was the faucet new when you got it? Have you taken the faucet apart? It's kind of tricky to get the side pieces lined up to go back together, so watch what you're doing when you disassemble. Make sure there are no obviously damaged pieces, anything that would make a bunch of turbulence as the beer goes through. If you haven't already, try pulling it wide open to pour, and shut it off somewhat abruptly, see if that changes the pint. I think they're really cool looking, so hopefully you can get yours working well. I had one for a while that wouldn't stop leaking so I gave up on it.

#### rgnlkngtylrbmbstk

• 1st Kit
• Posts: 18
##### Re: serving pressure
« Reply #19 on: January 30, 2012, 10:36:03 AM »
Re-reading your post, it sure sounds like you don't have enough resistance. Just to be clear, you aren't simply looking for X feet of y-diameter tubing. You need a particular amount of resistance, to bring your pressure down from 11 in the keg to about 2psi at the faucet. So the length of line is a matter of its resistance value, not how big of a hole you're sending the beer through.
Do you know much about the serving line? Brand name and ID/OD would help.