Beer line calculations - I'm a maths biff!!

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StrontiumDog
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Beer line calculations - I'm a maths biff!!

Post by StrontiumDog » Wed Jun 27, 2018 9:15 pm

So I have a corny keg of wheat beer in the fridge atm, cooling down to 2°C at a pressure of 10PSI which 'should' give me 2.5 vol CO2 (I don't like super fizzy)

I'm using 3/8" x 0.265" rigid beer line with a party tap on the end (temporary until I get a tap on a shank to go through the front of the fridge)

I don't know where to start with trying to work out the length of line that I need, I've been looking at the calculations and, for someone with the mathematical equivalent of dyslexia, they're terrifying to look at!!!!

Can anyone help?

Thanks all

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Kev888
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Re: Beer line calculations - I'm a maths biff!!

Post by Kev888 » Thu Jun 28, 2018 4:46 pm

There are rules of thumb that can help get you to the right place with minimal maths, and then use trial and error. If you have flow-control taps then they can tweak things too, though its best to get things 'roughly' right with the beer line, first.

Your keg is at 10psi, you want to leave one or two psi at the tap, so you need to drop about 9psi through line resistance. Check this as it has been a while, but IIRC 3/8"OD (~1/4" ID) beer line resistance reduces by 'roughly' 0.5psi per foot, if that, so you will be needing at least 9/0.5=18 feet of it. But it depends on 'things' so start with say 50% more and later cut it back if the pour is really too slow. It may even be worth actually timing the pour, rather than judging it - sedate is good for minimising foam, but when stood there with a glass for the first time it may seem to be taking much longer than it really does.

Thats why people who balance their lines well very often use 3/16" OD line instead. Its smaller bore has much higher resistance, so about 4 or 5 feet is usually enough.
Last edited by Kev888 on Thu Jun 28, 2018 5:06 pm, edited 1 time in total.
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StrontiumDog
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Re: Beer line calculations - I'm a maths biff!!

Post by StrontiumDog » Thu Jun 28, 2018 5:06 pm

Thanks as always Kev

Am I better off getting myself a couple of adaptors and some 3/16 line then? Rather not have to use 20 odd feet if I can help it

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Kev888
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Re: Beer line calculations - I'm a maths biff!!

Post by Kev888 » Thu Jun 28, 2018 5:17 pm

I personally prefer the 3/16" yes. Its rather easier to accommodate unless you actually need long runs, less wasteful of beer and cleaning fluids etc. and is nice and flexible too. Aside from needing adaptors (and even then many taps use it natively) I don't know of a down-side.

Though it should be said that if your taps pour smoothly and have flow control and all the lines can be kept cold then you may be able to work with much shorter 3/8" line than needed to properly balance it. Personally I never found that as satisfactory, but some people seem to manage okay.
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Re: Beer line calculations - I'm a maths biff!!

Post by john luc » Thu Jun 28, 2018 7:28 pm

you want 3/8"beer line in your tap and in your connector to the keg so buy 2 reducer connectors for 38" to 3/16" and 1.5 meters of 3/16" beer line to have between the keg and tap. the line can be coiled up if you want it to be used as a picnic style.
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StrontiumDog
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Re: Beer line calculations - I'm a maths biff!!

Post by StrontiumDog » Thu Jun 28, 2018 9:57 pm

Thank you both :-)

I've ordered 2 adaptors and 3m of 3/16 tubing so I'll cut it in half and go from there :-)

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StrontiumDog
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Re: Beer line calculations - I'm a maths biff!!

Post by StrontiumDog » Tue Jul 03, 2018 4:03 pm

john luc wrote:you want 3/8"beer line in your tap and in your connector to the keg so buy 2 reducer connectors for 38" to 3/16" and 1.5 meters of 3/16" beer line to have between the keg and tap. the line can be coiled up if you want it to be used as a picnic style.
Got my new beer line :-) will 1.5m be what I need? Should I crack on and cut my 3m in half or should I do a bit at a time?

Thanks again

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Re: Beer line calculations - I'm a maths biff!!

Post by StrontiumDog » Tue Jul 03, 2018 7:33 pm

Perfect!!!! Thanks guys :-) just need to get a tap for the fridge door and I'm sorted :-) Kept the full 3m length, pours a bit slow but gives me the option to up carbonation a bit in the futureImage

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