Length of beer lines

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balrog

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So we all must switch to SS lines
Simple
Expensive, & difficult, but problem solved.
 

beerme70

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If you took a poll I bet 90+% of folks are using 3/16" ID beer line over 1/4" barbs.
Actually, I am one of those that uses 1/4 ID line. I use 10 ft per keg, and am only traveling a short distance....say, 2 feet. Perfect pours every time.
 

day_trippr

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I did allow for 10%-.
But the physics say you're on your own island...

Cheers! :D
 

beerme70

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I did allow for 10%-.
But the physics say you're on your own island...

Cheers! :D
It's been a hot minute since I built my setup, and I do believe that I am wrong in my post. I think I DID in fact use 10 ft of 3/16. I am in the process of replacing my lines, and I do believe that I may have ordered 20 ft of the wrong stuff. Soooooooooooo, my bad.
 

GrowleyMonster

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I don't use any beer line. My faucet is right on the post. I had a lot of trouble with foam, and tried lower pressure. Still got a half glass of foam. Then I switched to a flow control faucet. Problem solved. Pour is slow, so no good for a bar or a big party, but works fine for me. But I have learned a lot from this thread about beer lines.
 
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TexasGuy

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Wow! My thread got really long...I just jumped in to update everyone...I was dong bad temperature conversion math in my head...my beer was not cold enough. After making the line 10 feet long with 3/16” tubing, I still had foam!

Then I found my thermometer...my beer was pouring at 40 degrees...lowered it to 35 and had perfect pours! But I wasted half the keg figuring it out...c’est la vie. My dad, in-laws and I emptied the keg on Thanksgiving...I’ll start my wife’s blood orange beer this weekend!
 

ScrewyBrewer

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Imagine you have 50 guys (CO2) on one end of a football field, shooting BB guns. On the other end, you have 1 guy (O2) shooting his BB gun back at them. Gas particles are so small, with such a huge area around them, that it is very unlikely that any of those BB's are going to collide and knock each other off course. It might happen every once in a while, but most of them are going to get through.
In regard to this scenario I have another question.

What if there was a strong wind blowing from behind the 50 BB gun shooters in the direction of the lone BB gun shooter? Where the Co2 under pressure were to represent the strong wind blowing at the lone shooter. I believe quarks can pass through solid steel as easily as they can the atmosphere. But it's hard for me to wrap my head around how O2 at atmospheric pressure can penetrate vinyl tubing filled with Co2 inside that is under pressure.

Of course I have no way of telling how this all works and I have replaced my old vinyl lines with EVABarrier double wall tubing in any case. Better to be safe than sorry.

eva-sml.jpg
 

doug293cz

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In regard to this scenario I have another question.

What if there was a strong wind blowing from behind the 50 BB gun shooters in the direction of the lone BB gun shooter? Where the Co2 under pressure were to represent the strong wind blowing at the lone shooter. I believe quarks can pass through solid steel as easily as they can the atmosphere. But it's hard for me to wrap my head around how O2 at atmospheric pressure can penetrate vinyl tubing filled with Co2 inside that is under pressure.

Of course I have no way of telling how this all works and I have replaced my old vinyl lines with EVABarrier double wall tubing in any case. Better to be safe than sorry.
Forget the BB's. Let's just focus on gas molecules. If you have a pipe connecting a CO2 tank (on the left) and an O2 tank (on the right), and both tanks are at the same pressure, then no "wind" flows thru the pipe. However, the individual gas molecules are bouncing around like crazy. If you look at a particular position along the pipe, there will be higher O2 concentration to the right, and lower O2 concentration to the left. All the gas molecules (both CO2 and O2) are bouncing randomly back and forth across the invisible plane at the particular pipe position. Since there are more O2 molecules on the right of the plane, more O2 molecules cross the plane from right to left, than cross from left to right. The opposite happens with the CO2 molecules. Because more O2 crosses the plane from right to left, the concentration of O2 increases on the left. This same phenomenon happens at every position along the pipe, so O2 slowly moves to the left, and likewise, CO2 moves to the right. This is diffusion. The rate of diffusion is affected by the total pressure, since the higher the pressure, the more molecules there are in each cubic inch, and the higher the density of molecules, the more often a molecule will bounce off another molecule. The more often molecules collide, the shorter distance they travel between collisions, so it takes longer to travel a distance many times longer than the "mean free path" (average distance between collisions.) Thus diffusion is slower at higher total pressures.

Under any specific set of conditions, a gas will have a diffusion velocity, which has units of length/time (cm/sec, in/sec, ft/min, etc.) Now let's say that the pressure in the CO2 tank is higher than the pressure in the O2 tank. This will create a "wind" in the pipe flowing from left to right. If the "wind" velocity is greater than the diffusion velocity of the O2 to the left, then the O2 molecules will be pushed back towards the O2 tank faster than they can diffuse, and O2 will be kept out of the CO2 tank. Naturally, the "wind" stops when the pressures in the two tanks have equalized. If the wind velocity is less than the diffusion velocity of O2, then O2 will still move left, but at a slower rate than the diffusion velocity.

However, when you have gas constrained in a vessel (tank, bottle, tube, etc), there is no" wind" blowing across/thru the vessel walls. All you have is small numbers of molecules diffusing thru the walls. The rate will depend on the permeability (to the particular gas type) and thickness of the wall material, and the difference in partial pressures of the particular gas on either side of the wall. The rate will be unaffected by the partial pressures of other gases. Each gas type will diffuse independently of any other gases present.

In a kegging system, the partial pressure of CO2 inside the lines will be 14.7 psi + the gauge pressure, so typically about 25-28 psi. Outside the lines the CO2 partial pressure will be about 400e-6 * 14.7 psi = 0.006 psi. Thus CO2 will diffuse from inside the lines out to the atmosphere. O2 is the opposite. The partial pressure of O2 inside the lines is very close to 0, and outside the lines it is about 14.7 * 0.21 = 3.1 psi. In this case O2 from the atmosphere will diffuse thru the line wall to the interior.

Brew on :mug:
 

Dland

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I know I've posted this link before, but I'm not sure why anyone would want all those coils of tubing over something like this or some other type of flow control device.

https://www.morebeer.com/ct/?idx=36879660&i=37030&u=/products/inline-flow-control-compensator.html

Considering the cost of the better beer lines, in long lengths, the price is reasonable too.

I have one and it works great, the over all length of my beer line is about 2 feet. That means very little beer gets oxidized even without the best tubing, and less beer in contact with plastic.

If I had a proper kegorator instead of my twelve keg coffin freezer, I'd get perlick compensated taps or similar.

I recently got one of these to replace picnic tap, it dispenses noticeably better.

https://www.morebeer.com/ct/?idx=36879848&i=38517&u=/products/pluto-beverage-gun-stainless.html
 

balrog

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This is diffusion. The rate of diffusion is affected by the total pressure, since the higher the pressure, the more molecules there are in each cubic inch, and the higher the density of molecules, the more often a molecule will bounce off another molecule. The more often molecules collide, the shorter distance they travel between collisions, so it takes longer to travel a distance many times longer than the "mean free path" (average distance between collisions.) Thus diffusion is slower at higher total pressures. ... the diffusion velocity.
That's what I was missing, the diffusion velocity.
 

ScrewyBrewer

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@Dland not being familiar with the formula in your post myself, I would guess you could also use it to estimate the rate at which O2 from the atmosphere would penetrate the beer line to the point were the beer inside it would become oxidized. Oxidized to the level at which off flavors are detectable by the average craft beer lovers' palette. That formula if written would provide us with perspective as to how long it takes for O2 to degrade our beer. Thank you for sharing your gas diffusion expertise with us.
 

Dland

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@ScrewyBrewer, I think you meant to thank doug293. I merely posted link to a devise that allows for use of short lines, yet good pours. It is adjustable, and you can change the resistance in the device to "simulate" different lengths of beer line.[/USER]
 

doug293cz

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@Dland not being familiar with the formula in your post myself, I would guess you could also use it to estimate the rate at which O2 from the atmosphere would penetrate the beer line to the point were the beer inside it would become oxidized. Oxidized to the level at which off flavors are detectable by the average craft beer lovers' palette. That formula if written would provide us with perspective as to how long it takes for O2 to degrade our beer. Thank you for sharing your gas diffusion expertise with us.
You could do this if you knew the diffusion coefficient for O2 thru the tubing material. For multi-layer tubing, each layer will have a different diffusion coefficient. You also need to know the thickness of each layer.

Brew on :mug:
 

ScrewyBrewer

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You could do this if you knew the diffusion coefficient for O2 thru the tubing material. For multi-layer tubing, each layer will have a different diffusion coefficient. You also need to know the thickness of each layer.
A typical 3/16 inch inside diameter beer line having an outside diameter of 7/16 inch. Similar to Bevlex 200 PVC 1/8 inch thick wall tubing. What would be helpful is knowing how long it would take O2 to penetrate the tubing to the point where off flavors are detectable. Whether it would take days, weeks, months or years of O2 seeping into the beer before its flavor is adversely impacted.
 

Robert65

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Hours, if not minutes, IME, with Bevlex. Always had to dump the line beer (first few ounces of a pour) if any time at all had elapsed, as it rapidly oxidized. I know that's not numbers, but you don't need numbers when there's such an obvious effect. Not so much the case with EVA barrier. And of course the beer in the keg is affected by diffusion through the line.
 
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