Flare fittings plastic to metal

[NLSurfer]

For plastic to metal fittings like this:

Should a plastic piece like so be inserted between:

I've read that they should or shouldn't be needed depending upon who you ask.

I realize with the ball lock taps they have a small rubber piece at the tip like so:

If going from a brass flare male end to a duo-tight female end there would be no such piece like that between them with adding a small plastic flare washer.

Also, does anyone have general advice on torque on these. Half past, quarter past hand tight, etc?

 

[McMullan]

I wouldn't use flare washers where plastic fittings are connected to metal. The plastic fitting does the intended job. To be honest, compatible metal flare fittings don't really need a plastic washer. If they don't fit well, use one. If I were you I'd forget about the plastic fitting and connect your gas valve and (and preferably grey) disco with barbed swivel nuts. It's going to be much more reliable and serve you for much longer.

 

[day_trippr]

You do not use a "fish-eye" washer between the Duotight fitting and the brass valve, nor with the quick disconnect.
The internal mating surface on that plastic fitting will provide all the deformation needed to achieve a gas tight seal for the brass interface, and the captive gasket on the end of the disconnect will provide that same deformation - somewhat redundantly...

Cheers!

 

[NLSurfer]

Thanks for the help! I was really hoping to go from these male flare end to EVABarrier tubing somehow.

Is there any other simple way to go from the male flare end to EVABarrier tubing? I tried some1/4 compression nuts and sleeves I had around but those don't work.

Maybe I'll just go back to the old school flare swivel nuts and vinyl gas tubing.

 

[day_trippr]

Is there any other simple way to go from the male flare end to EVABarrier tubing?

I haven't seen anything beyond the John Guest/Duotight/DMfit one-piece plastic fittings similar to the one shown...

Cheers!

 

[McMullan]

Is there any other simple way to go from the male flare end to EVABarrier tubing?

A swivel nut is the simplest way and, imo, the most reliable. They work absolutely fine with EVABarrier tubing.

 

[NLSurfer]

Do you mean use a swivel nut with a barb fitting and place the EVABarrier tubing over the barb?

Most of the EVABarrier tubing is 4mm inside diameter, and I see swivel nuts with 3/16 barbs. Would 3/16 be too big for 4mm tubing, or would it work with some heat and lube? I guess they also sell 5mm EVABarrier tubing too, which might work perfectly.

 

[McMullan]

Yes, 3/16 barbs are fine for 4mm ID EVABarrier tubing. I've got some with slightly bigger 5mm barbs. Dip the end of the tube in hot tap water for 10-15 sec then push over the barb, run under cold tap to shrink then clamp it. It helps a lot if the swivel nut is fitted to a disconnect first, before pushing the tube on.

 

[NLSurfer]

Thanks! I'll give it a go.

 

[Bobby_M]

There's nothing wrong with Duotight fittings on EVA barrier. I've sold over 10,000 feet of EVA and hundreds of of duotights and I can't count on one hand how many problems I heard about. Right, but I sell them so of course I'd say that right? Well, I sell bevlex tubing and swivel barbs too and the profit is all the same so.... I just rebuilt my own kegerator and it's 100% EVA and duotights.

 

[Bobby_M]

Thanks for the help! I was really hoping to go from these male flare end to EVABarrier tubing somehow.

Is there any other simple way to go from the male flare end to EVABarrier tubing? I tried some1/4 compression nuts and sleeves I had around but those don't work.

Maybe I'll just go back to the old school flare swivel nuts and vinyl gas tubing.

The only thing people are advising against is using the white flare gasket between those two fittings. No one said it won't work. You only need to use the white flare gaskets when the two opposing sides are stainless steel.

 

[NLSurfer]

Hi Bobby,

What does your duotight evabarrier tubing setup look like? Any chance you have a pic handy?

Did you remove all the barbed connectors from reg and add duotight from there, or are you using the kegland regulators too?

 

[NLSurfer]

So, I switched my duotight flare female fittings for some John Guest fittings and a leak issue I was having seems to have gone away. I was getting a small drop on the regulator overnight when I shut it off at the tank.

I noticed that the John Guest fittings have a much larger mating surface with flare. You can tell by the difference in hole size in the picture below (I know not the best pic). The plastic on the John Guest also seemed harder.

 

[McMullan]

John Guest are undeniably much better quality. If I need a push fitting for a particular job and John Guest do one, I'll go with John Guest. But I do use Duotight fittings when I have to. Fine on fixed systems, where the tubing doesn't get pulled in this and that direction, like on a mobile CO2 bottle/regulator; and where regular disassembly is required*. Push fittings aren't designed for repeated disassembly; the stainless teeth dull and the plastic wedge-like filaments holding them weaken due to stress fractures. In these cases I'd go with swivel nuts. Stainless swivel nuts are designed to be disassembled and reassembled until the cows come home. A lot tougher than push fittings, too. They are superior in some situations. They're not 'old school' at all.

Having said that, I'm looking at my modified cask setup and laughing, because it's literally festooned with push fittings:

*After extended use, and even when following good line cleaning practices, I was surprised to discover what looked like biofilms establishing inside beer line push fittings.

 

[NLSurfer]

Are you guys holding your pressure overnight (12+ hrs) and checking your high pressure gauge for a drop on your reg, or only holding it for an hour or two. I didn't notice a drop when I did it for 2 hours, but when I did it for 18 hrs and re-energized the primary it went up a bit more noticeably.

 

[Bobby_M]

Hi Bobby,

What does your duotight evabarrier tubing setup look like? Any chance you have a pic handy?

Did you remove all the barbed connectors from reg and add duotight from there, or are you using the kegland regulators too?

I don't. I just took the whole system apart again because my chest freezer failed. I'm in the middle of building a new kegerator but I'm going to put all the same EVA/Duotight back in that one too. I only use one pressure so off the primary I route one EVA line around the back perimeter of the kegerator and use the Duotight TEES to make taps for each keg. My primary reg uses male flare on the output already, but I would have changed out the shutoff valve to one with MFL on the output if I didn't already have it.

 

[Bobby_M]

Are you guys holding your pressure overnight (12+ hrs) and checking your high pressure gauge for a drop on your reg, or only holding it for an hour or two. I didn't notice a drop when I did it for 2 hours, but when I did it for 18 hrs and re-energized the primary it went up a bit more noticeably.

Did your pressure drop with the kegs connected or disconnect?

 

[NLSurfer]

With the kegs disconnected and none of the secondary regs pressurized. Just testing between the primary and secondary main line and manifold.

 

[Bobby_M]

Then you definitely have a slow leak that needs to be discovered. Soapy water on every joint, look for the fine bubbles.