Should i return this tubing?

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Ragman

Ragman

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I bought 39ft of Eva barrier 4mmID tubing and it won't fit over the barbs. So I was thinking about returning it and exchanging for the 6mm but then I started looking at the duo tight fittings which will work with 5/16th OD lines. So I'm wondering, should I try to return the lines or should I just keep the 4mm and order the duotight fittings. Hoping to spread this 39 ft between 4 kegs if possible. Hoping 10 ft for each keg would be enough. Currently running about 13psi

What do you guys think?
 
Right, the 6mm ID tubing has a larger OD (9.5mm) so all of the fittings would need to be re-bought.

What size are your barbs? I was able to run the 4mm up on 1/4" barbs using a heat gun - and the 5mm (which has the same 8mm OD as the 4mm ID line) on the (ridiculous) 3/8" barb on my Micromatic beer gas regulator...

Cheers!
 
I don't mind buying the fittings. It wouldn't be too much. My ball lock fittings are male threaded and I don't think I could pull the 4mm over that no matter how much I heated it up. Mainly wondering if I would have any issues using 4mm ID as opposed to 6mm ID
 
You don't size your lines for the fittings. You size the fittings for the lines. Using 4mm ID EVA will pour nicely on somewhere between 5 and 8 feet but I wouldn't go any longer than that or it's a bit slow. If you go up to 6mm ID EVA, you'll need to run at least 20 feet per faucet to balance. In other words, either replace the fittings or heat flare the tubing.
 
btw, you wouldn't run tubing over the 1/4" MFL threads on your QDs (or anywhere else) - that'd be crazy :)
You would use 1/4" FFL to [pick your tubing OD] push-to-connect fittings.

To that end, do yourself a favor and stick with John Guest fittings if you can. You can find part numbers on this handy fittings page - start on the Adapter section - then use the part number to find the best price wherever...

Cheers!
 
I've gotten the 4mm ID tubing over over 5/16 barbs pretty easy using boiling water and a swaging tool. First one took a couple minutes, but the 3rd one I had a routine of dunk in water, swag tool until friction, dunk, swag until friction, insert barb as far as it will go, dunk, put on QD while hot and push. About 30 seconds each after I got the procedure down. (and in my option works much better then the push fitting for CO2)

PXL_20210129_235302240.jpg
 
So I think with the beers I brew ( IPA's mainly but some stouts and porters) and the temp my Keezer is at that (36 degrees) I am going to keep the 4mm tubing, change my PSI to about 9 or 10, buy the Duotight DUO106 Push In Fitting - 8mm(5/16 in) x 1/4 in. Flare and the Duotight Push in Fitting DUO104 -8mm (5/16in) X Female Beer Thread - run my lines at about 7 ft and hopefully that should work for me. - Thanks everyone for your help.

If anyone sees anything wrong with the above setup, please let me know, I will be placing my order for the fittings soon.
 
I used these fittings:

- John Guest PM4508F4S for the 1/4" FFL to 5/16" OD adapters
- John Guest PI451015FS 5/8" BSP to 5/16" OD for the beer shanks.

From many reports it seems there may be a problem with the Duotight DUO106 design. At this point I can't recommend them...

Cheers!
 
I read some of the threads about Duotight but these are about twice as expensive as far as I can tell - is there a code or something?

2X the adapters you listed above = $22
2X Duotight from morebeer - $12
 
I installed about 50 duotights in a production brewery with confidence. I've also sold about 2500 of them so far and all the reports (about 4) of cracking were verified as being wrench tightened from the start. If users would heed the advice to lubricate the threads and hand tighten, these problems don't exist. If you're rebuilding an Chevy engine and the head bolt torque specs are 125 foot pounds, do you recommend buying a Ford because a head bolt sheered after torquing to 180 ft/lb? RTFM.
 
Bobby, all respect to you and whatever data you have, but going from the anecdotes here there's clearly too small a differential between "gas tight" and "circumferential crack" on those Duotight 1/4" FFL adapters to risk them when more hardy alternatives are available...

Cheers!
 
Bobby_M said:
I installed about 50 duotights in a production brewery with confidence. I've also sold about 2500 of them so far and all the reports (about 4) of cracking were verified as being wrench tightened from the start. If users would heed the advice to lubricate the threads and hand tighten, these problems don't exist. If you're rebuilding an Chevy engine and the head bolt torque specs are 125 foot pounds, do you recommend buying a Ford because a head bolt sheered after torquing to 180 ft/lb? RTFM.
Click to expand...

On the CO2 or beer side? They work great for me on beer side.

At least (10) of the ones that have failed for me I purchased from you, so you can bump that number a bit:). (Edit, checked and I've ordered (32) from you and about a dozen from other sources, out of which I've had about 15-20 fail with 8 of them being on a QD that did not see a wrench]. Several were on quick disconnects (developed after a month or two). I never use a wrench to tighten the quick disconnects, only manifold connections.

I'm an engineer, I read the datasheet/manual/whatever before using something new. Tubing is great and I do not regret the change, just cannot justify using the duotight connectors on CO2 when they can develop leaks at any time.

PXL_20210130_005345021.jpg
 
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I guess I need to do more reading but Im not sure as to why people use EVA barrier for gas. I mean, I can understand using it for liquid as what goes through those lines is what you drink but with the gas, as long as it dont leak, why does it matter?

(I like my pretty red gas lines)
 
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Gass diffusion is based on partial pressures of the gases, not total pressure. With 100% CO2 inside the gas line and atmosphere pressure outside there will be O2 diffusion through the 'red gas' line over time. The EVA barrier has a much lower diffusion rate. I kept some kegs on tap for 10+ months, preventing O2 from entering the lines is important to me.
 
So if I dont plan on keeping my kegs on tap for more than a month or 2, should I be OK? I dont want O2 in my beer either.

I guess I dont understand the science of it. If c02 is pressurized in a tube, and c02 is used to push O2 out of the keg when you purge, how the hell does O2 push its way into gas lines that are filled with pressurized c02?
 
Gases want to mix together, that's the short version. If there's no O2 in a line, pressurized or not, it still wants to go in.

If you haven't already be sure to give this thread a read regarding how to flare the tubing, what oetiker to use if you go that route, diameter information, not overtightening, and so on. It's good good info and tips.

https://www.homebrewtalk.com/threads/duotight-leaks.688681/
 
Diffusion of a gas is when molecules of that particular gas move from an area where they have a higher partial pressure to an area in which that particular gas exerts a lower partial pressure.

Diffusion is different from “bulk flow” (mass movement or convection).

'Bulk flow", gas movement is from a difference in total pressure, and the mix of different gases move together along the total pressure gradient.

Diffusion, gases move along their individual partial pressure gradients. In a static environment this continues until no partial pressure differences exist for any gases in the 2 areas.

The material of the line determines how fast diffusion through it occurs.
 

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