Resistance of 1/8" Line?

Hey,

Does anyone know how much resistance would be in 1/8" beer lines?... I can only find numbers down to 3/16".

-Eric

 

It's probably close to 3.5psi per foot but how would you get it over a barb?

 

I have access to some stainless 1/8" barbs. I was thinking of trying 1/8" just to see how it does.

 

Give it a try, I'm sure a bunch of us would like to know the outcome.

 

I experimented with 1/8" ID polyethylene tubing and I was able to use a 3 foot piece for a decent pour. The problem I have is that all my QB barbs are 5/16".

 

What psi was this at?
Thx

 

I'd assume around 30.... I have some I am playing with.. Seems to work well

 

Say it takes 10 seconds to pour a pint (16 oz). We can calculate the Reynold's # for 3/16" tubing easily enough at this flow rate and find it's 1562, meaning flow is laminar.

For laminar flow, resistance scales with the diameter^-4.

So if resistance is 1.5 PSI/foot with 3/16 tubing, then it's (3/16)^4/(1/8^4) * 1.5 PSI = 7.6 PSI / ft for 1/8" tubing.

Put more simply, it's a factor of 5. So if you need 10 feet of 3/16", you need 2 feet of 1/8" tubing.

Of course, this is all math, not real life, but I'm an engineer, so I of course wholeheartedly believe it.

(Edit: Fun question! Thanks!)

 

That sounds about right to me... at least for a theoretical approximation.

 

i just purchased some 1/8" ID tubing - I also am wondering where one can find the connection hardware for such a thing?

 

I think that is part of the issue with going that small on the tubing. The most common used fitting is a 1/4 I believe.

 

got a feeling i'm going to be putting together Frankenstein with the help of McMaster-Carr

http://www.mcmaster.com/

if anyone has done this and has any suggestions, let me know
and if I find somethign that works I'll do that same... like i said i'll probably try to put something together from McMaster-Carr in the meantime

 

Rootvonroot: what did you do? Did you find adapters? I want to use 1/8" ID Tygon silver with my keg and party tap.

 

you know, i never did get this idea to work :-(

 

If anyone needs some I did buy some 1/8 barb x female flare fittings to screw onto flare disconnects.

 

I am very interested. I saw some 1/8" barb fittings on the internet and Amazon. I am all for avoiding excessive beer line length, when the length is not needed for anything except to give more pressure drop. Bobby M helped me with this with his thread http://www.homebrewtalk.com/f35/17-id-polyethelyne-25-barbs-162964/

I calculated a concern with the 1/8" barbs. The ID is 0.078" so the area of the 1/8" ID is 2.6 times more than the area of the 0.078" ID. So the beer velocity thru the inside of the barb would be 2.6 times faster so the static pressure would lower (maybe someone can can how much). If there is no taper for the reduction in size, and there is no taper to increase to some bigger size, then there is "vena contracta" and turbulence and low pressure. I am concerned it would cause foam and more pressure drop.

But I am real interested if anyone did this, since that would trump any calcs, and I think there is a good chance it would work fine.

 

Just like how most 3/16" ID beer line fits well over 1/4" barbs, I figure the best barb for 1/8" ID line would be 3/16 but it's probably hard to find such hardware.

 

This looks like it would work.

http://www.mcmaster.com/#5670k47/=pjowz9

According to this thread, a standard 1/4" flare fitting has 7/16"-20 threads.

 

I know this is an old thread; but I have been planning on using 1/8" line for my root beer and seltzer water kegs - I just never got around to actually doing it. Back in 2011 I bought 1/8" fittings at chicompany and they have been sitting in my basement ever since. I have now just done an overhaul of my TDD-3 kegerator and figure I'll finally get around to trying the 1/8" line idea.

FYI, here is a link for 1/8" barbs for a 1/4" MFL:
http://www.chicompany.net/index.php?main_page=product_info&cPath=375_19_220_286&products_id=501

I hook everything up with 1/4" MFL fittings.

I tried the swirly things in the dip tube and they disrupt the flow too much - giving me too much foam.

I'll be getting some 1/8" line and installing these barbs on to a party tap and will figure out the length I need for my kegerator. I'll report back on the forum with my results.

I found an interesting site that might give a ballpark estimate of what the case might be:
http://www.pressure-drop.com/Online-Calculator/

If you put into this, say, 3/16" diameter hose (.1875"), a length of, say 6 ft, and specify your desired flow rate of 1 gal/min, it tells you that the pressure drop is 9.42 PSI. This sounds about right to me. Using D=.25", length=6', 1 gal/min gives a pressure drop of 2.41 PSI. Or about a quarter the resistance as with 3/16" hose - which sounds about right, I suppose.

If I put 1/8" hose in there, I get a 64.79 PSI drop!

Off-topic but what I just did with my True TDD-3 kegerator was:

1. Drilled out the 2" diameter tower holes to 3" diameter. I have 2 6-faucet towers on top and can't get 6 lines through a 2 inch hole with their flare fittings on and the 1" diameter cooling hose in the center. I should be able to easily do this with 3" hole.

Here's a quick pic I just took. I'm in the process of making an SS angle frame with casters to put the kegerator on, so forgive the mess:
https://plus.google.com/photos/1023...6234944663844860514&oid=102315020582698143827

2. I cut the 4" shanks down to 1-1/2". They took up too much space in the tower and had me using elbow connections and getting creative with the beer line arrangement! I cut them down to about 1.25" and drilled 3/8" holes in the back centers, and then used a 7/16-20 NF tap so that I can now directly connect a 1/4" MFL connector into the back of the shank. I currently put MFL/barb connectors in the back but am ordering from chicompany some M/M MFL fittings so that I can just put the same swivel MFLs onto each end of the beer line and just connect them to the shank's MFL.

Notice in my picture that I have now color-coded my lines (on the left tower at least) with vinyl electrical tape. I tape, say red, onto each end of my beer line, and then red tape the faucet handle of the beer line for that faucet. If I move kegs around I can just swap faucet handles to keep things straight. So now if I look at the beer lines inside my kegerator I immediately know which faucet they go to.

 

That linked calculator seems not all that well suited to our needs.
Try the only beer line length calculator worth using instead.
It might prove illuminating - particularly wrt the viability of 1/8" ID tubing...

Cheers!

 

Thanks for the link. I remember this now that I see it again.

Using that gives a length of 3.68 ft for 1/8" line on a keg carbed at 50 PSI flowing out at 1 gal/min (7.5 sec/pint). When I get the 1/8" line I'll see how this works out. If I start out with a 6 ft length of 1/8" line, it would flow out the tap at 9.83 s/pint (.76 gal/min).

I'm looking around on US Plastics site for which 1/8" ID tubing to use. Any suggestions?

EDIT:

I decided to go with a roll of Flexelene:
http://www.usplastic.com/catalog/item.aspx?itemid=25198&catid=0&clickid=popcorn

The stats look pretty impressive to me:
Antimicrobial
1/8" ID x 1/4" OD. 150 Working PSI @ 72°F. 450 Burst PSI @ 72°F. 1/16" Wall. 1/4" Bend radius.

A quick google has the first hit being "Coors chooses Flexelene for Beer Taps from Masterflex".

I suspect this stuff is probably pretty slippery inside; so I'll probably start out with, about a 24 ft length to test and hopefully snip down to as low as 6 ft or lower.

 

No real clue on the tubing. Not much call for 1/8" id lines on HBT over the years.

I just looked through the entire Kuriyama beverage tubing catalog and there's not a single 1/8" id line in sight.

That said, if you go to this mcmaster-carr page and set the filters for use with food, plastic, PVC, 1/8" id, you'll find there are products out there...

Cheers!

 

Well I got the 1/8" line in today and performed my test.

For about a week I have been carbing a keg of water at 50 PSI through both the in and out posts - shaking it about a half dozen times a day. It is pretty well carbed - I'm drinking some of this seltzer as I'm writing this.

Here is a picture of what I did. I need to learn how to take good pictures. It didn't show up at the resolution or with the clarity I would desire; but here it is:

https://lh3.googleusercontent.com/-...w0sKI/w418-h235-no/IMG_20160106_181632827.jpg

The blue line is the 1/8" Flexelene. I started off with a 12 ft piece of this. I rigged up a 16" piece of Bevlex-200 3/16" line (the clear line) with a party tap at one end and a 1/4" MFL flare fitting (male/barb fitting) on the other end. I had 1/8" barbs w/swivels (1/4" FFL) for the 1/8" line but quickly realized that I don't have any tiny little clamps to clamp the barbs on! So I took 2 pieces of the bevlex-200 hose about 3 inches long and reamed them a bit with my snub-nosed pliers to slip the 1/8" flexelene into the bevlex-200. I could only get about 1-1/2" of the flexelene into the bevlex; but that was good enough. I cut the ends off so that the flexelene with the bevlex around it was at the end. Then I had to ream a little inside the flexelene with my snub-nosed pliers to install the 1/8" barb swivel fittings and then used my normal clamps over the bevlex/flexelene ends to clamp the barb/swivels onto each end of the 12-ft flexelene piece. The end result was a 12 ft hose of 1/8" flexelene with 1/4" swivel FFLs on each end. I screwed the party tap piece on one end and the keg post fitting on the other. If I knew how to take a good picture you should be able to see all of this. If you squint at the one I put here, you might be able to make out all I've just described (including the 50 PSI on the CO2 gauge).

Anyhow, as it is right now, the 12 ft piece pours very very well. If anything, it is pouring a bit slow. I am going to keep it this way 'til the weekend. I am going to test around with standing at various heights with the party tap as it is now and see how the pour differs. But right now, I just want a few beers and go to bed. I don't like to do anything that might require thought when I'm drinking

I should have mentioned that I used an 8 ft piece of the bevlex-200 (3/16" line) with the party tap on the keg first to see what that was like. The seltzer shot out at a bazillion mph. Also, as an FYI, when putting the flexelene-attached keg fitting on the keg, you could feel the back-pressure immediately. My palm bounced up a bit putting the post fitting on.

 

I did a few tests - mainly to verify (or not) that hose length calculator at:

http://www.mikesoltys.com/2012/09/17/determining-proper-hose-length-for-your-kegerator/

I did 3 tests with my 50 PSI seltzer and found that it is currently pouring very near 1 oz a second. I used a small bucket and a kitchen scale during these tests. That works out to 16 seconds for a pint (16 oz).

I felt this was normal and so I then pulled out my Sam Adams 16 oz tulip glass and filled it with my beer arrangement in the normal way I do that - to the line about 2 inches below the top of the glass (the rest is head). This turned out to be about 10 oz in 10 seconds.

So the pour on my beer is about the same as the current arrangement of my seltzer. The seltzer is 50 PSI going through 12 ft of 1/8" hose and the beer is 10 PSI going through about 6 ft of 3/16" hose.

I only just now found out that my Sam Adams glasses only hold 14 oz of water (weighing it with a scale) and that I actually only drink about 10 or 11 oz at a time out of these glasses.

BUT that then throws off my thinking about that hose calculator at:
http://www.mikesoltys.com/2012/09/17/determining-proper-hose-length-for-your-kegerator/

Is that thing calculating 16 oz as really 10 or 11 oz? Because it works out fairly well for me in these tests I've done; but I'm calling 10 or 11 oz 16 oz!

Has anyone on this board run through this calculator with actual experiments measuring weights? I think it is good if you call a "pint", say 12 oz!