Header Tank Vent Line

[Dave S]

Curious......

The header tank vent line on our S-7 which goes to the starboard fuel tank top is made of some version of tygon (near as I can recall from previous laboratory work, there are about a zillion version of tygon).

Has anyone swapped this out and used a standard fuel line in its place?

Wondering about this since the type of tygon used does not have any reinforcement (some types of tygon do).

A person can cut anything tossing a sharp enough object in the back hard enough (passengers), but since a standard fuel line has reinforcing braids between the layers it would seem to be a bit stronger. Also wondering if it has ever happened having a less than brand-new tygon tube snap due to cold weather or embrittlement with age.

Thanks for your feedback,

Sincerely,

Dave S

KF 7 Trigear
912ULS Warp Drive

St Paul, MN

[Geowitz]

My concern would be being able to visually see the fuel in the vent line. It gives me a warm and fuzzy that the system is operating correctly when I can see it flowing. I have mine frequently secured so the likelihood of it getting caught on something is pretty slim. No real advice on the brittleness, but it's cheap and easy to replace. I have the blue stuff from spruce for when I replace mine. They claim lots of good properties including low temp resistance and pretty high tensile strength to be 50psi rated.

http://www.aircraftspruce.com/pages/...e/bingfuel.php

[Slyfox]

yup, same stuff I use. also take and put one of those low fuel warning things in there, in the vent line that is. that way if the fuel isn't going into the header tank for any reason, you know. than you have about 15 min to correct it or land.

[kmach]

Hi, the tygon in my model 5 is still very flexible after six years. It is exposed to - 20 , but is hangared. I think if exposed to long periods of uv light it would get hard sooner.

[DesertFox4]

I also use the blue Tygon from both tanks down to the header tank and the vent line. I also use it for my fuel site gauges. I change it out every year at conditional inspection time. It is always very flexible after one year. Av-gas does discolor it a little in one year hence my reason for changing it that often. That and it is very inexpensive.