[georgemohr]

Hi all,

I'm using the 1/4" OD tubing from Stein, and I'm using his push-on fittings for items that might be removable (instrument connections for example). However I'd like something more permanent like a barbed aluminum fitting for connections inside the airframe.

Does anyone have a source for such that fit the ID of this tubing?

Thanks!
George

 

[Carl Froehlich]

I’ve had good luck with the push on fittings from Stein. If you are looking for something more robust then Nylo-Seal is what you want.
https://www.aircraftspruce.com/menus/ha/fit_znylo.html

Don’t forget the tubing inserts to go with the fittings.

Carl

 

[georgemohr]

These look just exactly like what I need. TY!!

 

[BlackhawkSP]

Hi all,

I'm using the 1/4" OD tubing from Stein, and I'm using his push-on fittings for items that might be removable (instrument connections for example). However I'd like something more permanent like a barbed aluminum fitting for connections inside the airframe.

Does anyone have a source for such that fit the ID of this tubing?

Thanks!
George

McMaster-Carr has many types too:

https://www.mcmaster.com/products/tube-fittings/brass-push-to-connect-tube-fittings-for-air/

 

[Bavafa]

I’ve had good luck with the push on fittings from Stein. If you are looking for something more robust then Nylo-Seal is what you want.
https://www.aircraftspruce.com/menus/ha/fit_znylo.html

Don’t forget the tubing inserts to go with the fittings.

Carl

Two thumbs up for the Nylo-seal, the only down side is that they are somewhat bulky. But they provide an excellent seal and very easy to install/remove.

 

[lr172]

Two thumbs up for the Nylo-seal, the only down side is that they are somewhat bulky. But they provide an excellent seal and very easy to install/remove.

+1 Just dealt with a few leaks in my PTC fittings at last Pitot Static. Replaced all with nylo seal.

 

[georgemohr]

Agree, I've purchased a few to play with.

I know the push-on connectors work, but I'm very concerned about their longevity. They rely on an o-ring sealing around the OD of the tube with nothing but then insertion pressure to effect the seal. I'm feeling like over time as those o-rings age, they will start to leak.

 

[blaplante]

I would think degradation of an o-ring in a dark place (no UV) and exposed to zero chemicals/solvents (no oil, gas, etc) would be MANY years.

 

[scard]

I've mostly shunned PTC and nylo-seal all together in favor of simple tygon tubing and barbed fittings. No leaks and much easier to work with.

 

[Bavafa]

Agree, I've purchased a few to play with.

I know the push-on connectors work, but I'm very concerned about their longevity. They rely on an o-ring sealing around the OD of the tube with nothing but then insertion pressure to effect the seal. I'm feeling like over time as those o-rings age, they will start to leak.

Another thing to watch out for in a push-on connectors is that they seal much better in a positive pressure and not vacuum. This is especially true for the cheap ones.

 

[Mikeyb]

Nylo-Seal is a reputable brand name of specific product. PTC is generic to many fittings from many sources. Parker Prestolok fittings were selected for use on NASA microwave cooling applications 20 years ago. Hundreds of connections maintained by technicians around the world without a single reported leak. Maybe a bad comparison to pitot static systems but it’s a good picture!
Mike

 

[blaplante]

I would think degradation of an o-ring in a dark place (no UV) and exposed to zero chemicals/solvents (no oil, gas, etc) would be MANY years.

 

[Bavafa]

I would think degradation of an o-ring in a dark place (no UV) and exposed to zero chemicals/solvents (no oil, gas, etc) would be MANY years.

The Nylo-Seal also seal with an o-ring and probably has the same chance of failure. It would be many years but also easy to replace.

 

[bjdecker]

Another vote for Parker PrestoLok

I ripped out all of the nylo-seal stuff a long time back and installed Parker Prestolok fittings for *ALL* of the pneumatic systems in the airplane (AOA, Pitot, static.) and Parker PE/LLDPE tubing. (.170"ID, .250"OD)

https://ph.parker.com/us/en/product-list/composite-push-to-connect-fittings

 

[BillL]

Key word: Cheap

Another thing to watch out for in a push-on connectors is that they seal much better in a positive pressure and not vacuum. This is especially true for the cheap ones.

Nothing against the Parker brand/design but it seems when humans (me included) have a problem with something they want to change the design of the thing that failed. The internal details of the PTC products vary considerably. Cheap is not a reliable way to go. Example: I had a leak in my RO system and wondered about some PTC connectors at the hardware store. They were dissembled and had plastic barbs used to retain the tube. If low cost 1/4" poly tube is used it maybe OK, but SAE nylon brake tube (higher pressure and durometer) is too hard for the barbs to dig in and hold the tube.

Quality fittings from Stein (and likely others) use stainless retainers and don't have this issue.

The o-rings in the RO lasted 20 yrs before taking a set and leaking.

Either get a trusted source and brand or take the time to know the details. Much easier/faster to do the former when building. Stein has had good parts for me.

Vinyl + barbs - in my VARTM efforts this has presented leak issues and in other applications found ease of disassembly to be a negative. YMMV. Again, it may be the quality of the components. I finally used sticky tape to cover all the connections to solve the leakage issue. Then it would hold -29" Hg (what ever the gauge says) for 24 hours.