PSA: Duotight Actually Does Need Grease

[AlexKay]

Duotight fittings and EVABarrier tubing work really well together, and I’ve always found it relatively straightforward to just hook everything up and have it be leak-free without further worry.

But. It is, in my opinion, all too easy to fail to insert the tube all the way into the fitting, past the second (“duo,” natch) o-ring. Then it is generally still leak-free, up until the point where you strain the fitting, at which point either gas or liquid comes shooting out.

I am here to report that it is highly recommended to coat the end of the tubing in food-grade keg grease before inserting into the fitting.

“Well, duh,” you might say. But until yesterday, I had always been content just muscling the tubing in. Things have changed:

On the right (light gray body, dark gray release ring) is an older Duotight fitting. It has always been my experience that a judicious application of force will seat the tubing correctly, no grease needed.

On the left (dark gray body, black release ring) is a fitting I just bought. No amount of force I was able to apply would guarantee a two-o-ring seal while dry. It needs grease.

Posted so others can learn from my mistakes.

 

[Deadalus]

Not to side track your suggestion but I think the lighter gray fitting is John Guest or another manufacturer. I could be mistaken but I've found Duotight flare x ptc to be skinnier, like left.

Personally I've purchased several of the newer Duotights with the black rings and they seemed easier to set. I'd say that relates to the collar more readily extending.

One possible trend I've noticed is that any residual bend in the Evabarrier sometimes makes insertion harder.

 

[wepeeler]

I have had a few people respond that twisting the tubing into the new duotights can damage the teeth, but that has not been my experience. No grease needed. Just a slight twist as you insert and the tubing seats all the way. I haven't had any leaks since.

 

[day_trippr]

I have almost 50 PTC fittings in service and never used grease on any of them
I use a legit tubing cutter and put a Sharpie mark on the tubing ends to show the full insertion depth...

Cheers!

 

[worlddivides]

I might need to try this. I've never had any problems with the Duotight fitting I use for gas. Zero leaks. However, the Duotight I use for liquid only fits snugly with no leaks maybe 20% of the time. The other 80% of the time it leaks. Now, I tried a ridiculous number of adapters before using Duotight and they ALL leaked, and Duotight is the one that leaked the least, which is why I use it, but I'm not sure what the trick is. I generally only use Duotight for closed transfers, having my normal liquid quick disconnect have the beer line forced over both ends with zero leakage (but I use Duotight on the gas quick disconnect with zero issues).

I might need to try keg lube just to see if it does stop the leaking.

 

[AlexKay]

I have almost 50 PTC fittings in service and never used grease on any of them
I use a legit tubing cutter and put a Sharpie mark on the tubing ends to show the full insertion depth...

Cheers!

Well I have over 100 PTCs and …

I also have a purpose-built plastic tubing cutter. I like the Sharpie idea, but with this last batch of the newest Duotights, the problem wasn’t knowing whether the tube was all the way in. It clearly wasn’t. The problem was that no matter what I did to finesse, wrangle, or force the issue, I simply could not get the tubing inserted properly. Until I went and got some grease.

 

[day_trippr]

I don't recall ever seeing someone prescribing grease before.
I'd at least make sure whatever you're using for lubrication is compatible with the gasket material...

Cheers!

 

[simbabrew]

I use a bit of Keg Lube on EvaBarrier tubing that I plan to insert and remove over time. The DuoTight's have twin O rings inside, and I think the lube helps preserve them when the tubing is being inserted and removed repeatedly.

 

[odie]

I recently started using keg lube...highly recommended.

I had leaky fitting...then I realized there was a "depth gauge" on the fitting. So I used that but half the time I couldn't get the tube all the way in.

a little keg lube helps a lot...and even then, some fitting were still very hard to get all the way in.