Originally Posted by AKNick

Doing a little maintenance and noticed my clunk line grew... let’s just say I have viton in there now! Wowza.

You think this could have contributed to the flameouts you had with your GP76?

Originally Posted by ghoffman

So, why use anything other than Viton?
The translation from lawyer to English: Tygon really doesn’t work with gasoline, but it is cheaper...

Exactly. It’s far cheaper (something like $1 vs $5 a foot right?) and I like that for applications outside the tank I can SEE fuel flow through tygon. More than once that has helped me diagnose carb issues and running problems, watching the lines to confirm the pump pulses or look for air bubbles.

As you know I am 100% onboard with viton clunk lines. I’ve been using it in tank since at least 2012, if not earlier.

I worry about Tygon swelling and getting hard, expanding on the fittings, so I just ordered 5 feet from McMaster and it is done. If the carb is getting gas, I know all is well. I can’t see them when I’m flying anyway.

Originally Posted by ghoffman

I worry about Tygon swelling and getting hard, expanding on the fittings, so I just ordered 5 feet from McMaster and it is done. If the carb is getting gas, I know all is well. I can’t see them when I’m flying anyway.

If Viton 'all the way' gives you peace of mind then that's the best reason to use it!

Originally Posted by Hinckley Bill

If Viton 'all the way' gives you peace of mind then that's the best reason to use it!

Probably true. When I see yellow Tygon now, my brain immediately thinks “future failure”.

Originally Posted by crankcase

Just to clarify the Sullivan tubing formulations.

I think in your test so far you have the Sullivan "Tygon" which to me seems like a yellow tinted polyurethane in my opinion.

Proflex would be a variant of FKM, I believe.

Then we have Sullivan Buna high temp smoke oil tubing. Not discussed in this thread so far.

If you were to take the Sullivan "Tygon" in my photo below and introduce it to a heat gun or even an open lighter flame. It will exhibit much different results that that of Tygon F-4040-A which is the standard Tygon tubing that we are used to & manufactured by Saint Gobian. Dubro Tygon line is just repackaged lengths of F-4040-A .

The Sullivan "Tygon" will immediately turn glossy and almost immediately catch fire under flame. Once extinguished & cooled it will be rock hard. Tygon F-4040-A will get slightly glossy & char. It will not ignite as easy even sustained under a flame. Once cooled it will still retain the same flexibility as it did without exposure to flame. This leads me to at least conclude that Sullivan "Tygon" and Tygon F-4040-A are not the same formulation.

So at days end.... which tube for inside the gas tanks.

The blue flor, I understand, is very fragile.

Thoughts.

Originally Posted by Kitchenman

So at days end.... which tube for inside the gas tanks.

The blue flor, I understand, is very fragile.

Thoughts.

Viton inside the tank.

Bob

Originally Posted by BobUSA

Viton inside the tank.

Bob

Viton inside, no question. It is completely inert to gasoline. And at $4.50 a foot, $10 plumbs the entire plane. I have found that the yellow or blue stuff even takes a permanent set on the fuel dot, and does not seal well.

which is the VITON you purchase?

This one https://www.mcmaster.com/5119K41/

Originally Posted by RCAddiction

This one https://www.mcmaster.com/5119K41/

Correct.

I just looked up my 1st order of 10' of that Viton tubing p/n from McMaster: 6/9/2008.

Zero of that line has hardened or changed at all, whether inside tanks, or on fuel pumps, etc. And no, I don't use ethanol-free fuel. Normal 89 or 91 octane pump gas from a good quality brand like Shell, etc.

Originally Posted by RCAddiction

This one https://www.mcmaster.com/5119K41/

thank you so much!

that is the one I ordered. I am maybe 50% done setting ups this airplane:

Viton is one of those things that archeologists will find 1000 years from now and it will be useable.

Originally Posted by RCAddiction

This one https://www.mcmaster.com/5119K41/

Will this be good to fit DLE 55 carb and tank lines ?