Clunk Line

[zzw26n]

	Quote: Originally Posted by Sevans16
	I have some dubro neoprene(black) fuel line. Is it any good?

I wouldn't use the Du-Bro, it has a seam and tends to split there. Buy the HAYES.

[JoeAirPort]

I have had GREAT results with the Hayes stuff thanks to RCIGN's post a few year back. I use a brass nipple in the middle of mine to keep it from folding in half and going to the front of the tank. I always use barbs and zip ties. I had one slip off. I had one stay on without the barbs. Not sure why one would slip off and the other not. But the clunk line is one of the most important things to get right on your plane. Use Hayes, I have one on for a few seasons now. It's still very flexible. No need to replace it.

[Sevans16]

ZZ-Thanks for the tip on the dubro neoprene. I knew I had read something like that years back in my heli days.

[XJet]

	Quote: Originally Posted by bodywerks
	Are you sure the fuel tubing you got is tygon? Or is it just semi-clear yellow tubing that looks like tygon? I ask because some ARF companies(aeroworks for sure) provide fuel tubing in their kits that is only good for practicing your granny toss into the trash can.

You're dead right.

I bought some "tygon" from a hobby shop (or at least it said "tygon" on the package but noted that it didn't have tygon written on the tubing itself.

After a few months I took the tank out and found that the clunk line was as stiff as if I'd been running 20% viagra in my fuel.

Rock-hard -- in fact I'm surprised it didn't snap when I tried to bend it.

I have tried neoprene but found that I end up with tiny black particles in the bottom of the tank within a few hours and the surface of the tubing goes slightly rough. Perhaps it's something in the fuel that's affecting it but I've gone back to *genuine* tygon that I'll be checking every couple of months.

[JoeAirPort]

	Quote: Originally Posted by XJet
	You're dead right. I have tried neoprene but found that I end up with tiny black particles in the bottom of the tank within a few hours and the surface of the tubing goes slightly rough. Perhaps it's something in the fuel that's affecting it but I've gone back to *genuine* tygon that I'll be checking every couple of months.

What brand neoprene was this? I hope it wasn't the Hayes stuff. I never noticed anything like that in my tanks. I even had an in-line filter on it for a little while and nothing was in the ultra fine screen when I opened it up.

[RCAddiction]

Clunk Lines:

1. Viton 60 durometer 1/8" ID, 1/4" OD @ McMaster
http://www.mcmaster.com/#search/5119K41

2. EasyFlex @ Aerotrend
http://www.aerotrend.com/shop_subcat...ea0cd769085af9

3. Hayes medium neoprene line at TowerHobbies
http://www3.towerhobbies.com/cgi-bin...&I=LXK824&P=ML

Vent Lines and other lines external to the fuel tank:

4. Genuine 1/8" ID Tygon tubing from McMaster. It comes in large rolls and in a real Tygon box.
http://www.mcmaster.com/#search/5552K23

I hope these links are helpful.

[XJet]

	Quote: Originally Posted by JoeAirPort
	What brand neoprene was this? I hope it wasn't the Hayes stuff. I never noticed anything like that in my tanks. I even had an in-line filter on it for a little while and nothing was in the ultra fine screen when I opened it up.

Dubro.

I tried in two tanks and got the small particles appearing in both.

It might be something specific to our gasoline perhaps.

[bodywerks]

	Quote:
	I've been contemplating the Aerotrend Aquablue. Is there any difference between Easyflex and Aquablue, except the size?

The aquablue is similar in stiffness to your average tygon tubing, maybe a little stiffer. It is still gas compatable and will outlast chinese junk.

	Quote:
	To say that the Aqua Blue or "standard" stuff is stiff, is to participate in an example of extreme understatement. The EasyFlex is very similar in it's flexibility to other commonly used fuel line types albeit a bit stiffer than say Tygon or neoprene.

Hmmm, can't say I disagree, necessarily since I haven't used tygon in a while, but I seem to remember tygon being noticeably stiffer than easyflex. All I know is that the easyflex stuff flops around quite readily inside the fuel tank, and blue looks cooler

[RCAddiction]

defintely...everyone knows that the blue looks cooler. Use blue for supply line and yellow for your vent line. Very cool.

FLEX
I have both Tygon and Aeroflex in my workshop (and Hayes and Viton and silicone). When new, the Aeroflex is slightly more flexible than the Tygon in the same size. The Aeroflex also tends to stay flexible longer than Tygon when used inside the fuel tank. Yes, it hardens also, but seems to take longer to harden using the gas blends I've run in Chicago and Charlotte.

Hayes is THE softest and the most flexible, but you usually need a stiffener as has been mention, like a length of brass tube, etc so that the Hayes line itself is not much longer than 2" or so.

Viton 60 duro initially is as flexible as yellow Tygon, but stays that way in fuel. Downside....it is far more expensive to use. I use it for clunks, and for the lines in my fuel jug, so that i never have to replace them.

[smokin]

i lost a SUPERXTRA at the bottom of a very low inverted flat spin due to my engine quitting.....
i found out after much searching that my tygon tubing in the tank could be used to pole vault with! i then made the switch and will never go back!


AEROTREND TUBING

get it at TBM or AIRWILD.


this is THE stuff!

[Zeeb]

	Quote: Originally Posted by RCAddiction
	4. Genuine 1/8" ID Tygon tubing from McMaster. It comes in large rolls and in a real Tygon box. http://www.mcmaster.com/#search/5552K23 I hope these links are helpful.

Hah, there it is....

I knew the number had a bunch of 4's in it

I couldn't remember the number for the Tygon you can use as fuel line, but this link RCAddiction provided shows it in the specs;

"Tygon formulation F-4040-A"

If it doesn't say that on the tubing, it isn't the right stuff. As I noted before, Tygon comes in lots of flavors and we used to use it quite a bit for various things in the air ambulance transport modules we put into aircraft and helicopters. IIRC, only the F-4040-A is gasoline compatible. Then there is the fact that other manufacturers produce yellow tubing. Who knows if any of that is gasoline compatible?

Nick is right on the EasyFlex as I just went and compared some to Tygon, it is just a tad stiffer but almost un-noticeable. I don't have any of the AquaBlue around anymore and maybe the package I got was bad or something, but it wasn't a whole lot more flexible than brass tubing.

And yes the EasyFlex will get stiff over time, but I usually change my lines each year and I've yet to find a piece of it that was stiff where I used to find Tygon stuff that was getting marginal after a year.

I think the OP has enough info to take action now...

[RCAddiction]

Okay, I've done some "flex deflection" testing.

• Precisely measured 4" lengths of new samples of the fuel tubing were fed thru a 1/4 ply plate. 4" seemed like a reasonable length for a moderate sized fuel tank.
• The plate is thick enough and holes fit tight enough so that the tubing did not flop around in each hole
• 4 identical fuel clunks (same weight, brand, etc) were applied to the end of each piece of new tubing.
• The Aerotrend had a bit of a curve to it which I oriented laterally, to minimize any effect on the direction of the deflection test. The Tygon had a smaller curve to it.
• Except for the 3/16" Hayes, the other tubing is nominally 1/4" OD.

Photos:

1. Tubing hanging vertically with clunk at bottom, left to right.
2. Tubing hanging vertically with clunk at bottom, front to back.
3. Tubing plate rotated counterclockwise to observe amount of deflection of each tubing with the same weight on it
4. Tubing plate rotated back clockwise to observe the amount of deflection in the opposition direction
5. Tubing returned to vertical hanging position once more to ensure nothing had moved significantly.

Left to right and front to back - the Hayes is the thin black tubing. The Viton 60 durometer is the thick black tubing, then the Blue EasyFlex, then the yellow genuine Tygon.

Results

• Within the realm of our use, the Tygon, EasyFlex, and Viton are very close to identical when brand new. The EasyFlex ultimately had slightly more deflection but it was not immediate.
• The Viton reacted more quickly to a change in direction than the other 2. If I had 3 hands, I would have taken a video to display this.
• The Hayes is significantly more flexible. It has the advantage of being smaller in diameter, with thinner walls, and is a softer material.