Clunk Line

[RCAddiction]

Al, actually the Japanese carmakers were sticklers for fluorosilicone (Viton is fluorocarbon) and liked to use LCP (liquid crystal polymer) for pump inlets since while expensive, it was dimensionally extremely accurate and chemically resistant.

Not saying these are accurate today, but they were in 1990:
Ford - get it done right
GM - get it done on time
Chrysler - get it done cheap - hence the Buna-N. Stupid decision, parts failed within 6 months.

[Al Lewis]

I use quite a lot of BunaN. We mill our own for some applications but certain things I design for are very particular about what gets near them so Viton is also used a lot.

[RCAddiction]

Viton is great, except when cold. That's was the main advantage of Fluorosilicone, lower temp capability and lower durometers possible than Viton.

[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.
Real tygon should last a year minimum, but I prefer Aerotrend Easyflex. You can get it directly from them online, through Airwild hobbies, or at your LHS if they carry it. I swear by it and have never had to change it out.

[RCAddiction]

Aeroflex is a good alternative if you can't get Viton easily. I've also found it to stay flexible, longer than Tygon and certainly better than the terrible yellow PVC tubing being passed off by ARF makers as Tygon. The problem is that Aeroflex has become more difficult for me to obtain, unless I order direct from Aerotrend.

[Sevans16]

I'll second the Aeroworks fuel line is junk. I had. An AW 75cc Extra. I had radio failure during the 5 flight. A month later I pulled the tank apart and the clunk line was hard as a brass tube. WTF??? I should note the fuel line outside the tank is fine but only 6-8weeks since it held gas for the first time.

So I am on the look out for a clunk line. I know a lot of heli guys run the Hayes but say to change it once a year, they run 30% and there is something about the exhaust that's is hard on clunk lines.

[A-Track]

I've had good luck with the du-bro stuff, some of my lines have been on the plane for a few years and are still almost like new. I have used other stuff in the past can't remember exactly who made it, might have been sullivan, but that stuff turned rock hard in a couple months of flying.

[StevL]

	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.

Now that is a good question. This was semi clear yellow tubing provided by H9 with their Carden Edition Yak.

I have a SD Extra 260 that I know I used Tygon. I'm going to take the fuel tank apart this week and see how the clunk line is in this one.

[Sevans16]

I have some dubro neoprene(black) fuel line. Is it any good? It's all I could get at the LHS. I need to order something I guess? Anyone have info on the Viton tubing. I have a grainger account. I have not ordered from McCarr in ages!!

[sgillmore]

	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. Real tygon should last a year minimum, but I prefer Aerotrend Easyflex. You can get it directly from them online, through Airwild hobbies, or at your LHS if they carry it. I swear by it and have never had to change it out.

Great information here. After many years in R/C, I'm just getting into gas. I believe this one thread alone has given me info that will be prevent a potentially frustrating and possibly disastrous problem.

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

Also, what do most people use on a 50cc...3/32 or 1/8?

Thanks.

[Zeeb]

	Quote: Originally Posted by StevL
	Now that is a good question. This was semi clear yellow tubing provided by H9 with their Carden Edition Yak. I have a SD Extra 260 that I know I used Tygon. I'm going to take the fuel tank apart this week and see how the clunk line is in this one.

Well like all things technical, not all are as they appear....

Tygon is a brand name and it comes in various flavors for different fluids. IIRC, the 4044F is the stuff you want for gasoline????

I don't remember for sure as I don't use it anymore, but the stuff has the numbering on the tubing itself.

Now as for neoprene, same story; different blends are commonly available and usually just called neoprene, doesn't necessarily mean it's gasoline compatible.

Frozen seals on a 40 + year old aircraft still being good? Well I won't dispute that as I don't have much personal knowledge about the retrieval and restoration of that P-38. But I will say there is a LOT of difference between the seals/lines one might find in automotive use and the MIL-SPEC stuff used on full scale aircraft.

I like the Aerotrend Easyflex, but as noted above it is getting difficult to get.

[Zeeb]

	Quote: Originally Posted by sgillmore
	I've been contemplating the Aerotrend Aquablue. Is there any difference between Easyflex and Aquablue, except the size? Also, what do most people use on a 50cc...3/32 or 1/8? Thanks.

Ahhh, another question I had which was only answered by buying both Aerotrend types.

Are you familiar with the old joke about the state of the male member on a honeymoon night?????

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.

1/8" is the size I use and I think most will tell you that size is what's normally found on the gassers.