Sealant for polyethylene fuel tank?

"d.l.anderson" wrote in message
...

Here's a link to a Kitfox builders site. It's not my site, but it has good
pictures of the exact same header tank itself:
http://www.scoobysworkshop.com/2005p...tors_small.jpg
http://www.scoobysworkshop.com/2005p...Done_small.jpg

There's no real build up, but the tank has thick enough walls to allow a
bit
of thread. There's no openings to allow nuts to go in, meaning that viton
ring approach is practically rules out. The guy that made the pictures has
used some kind of kit or glue to bond the brass inserts into the tank, and
it's this kit that eventually gives way and develops leaks. We got the
tank
from a previous owner who was honest enough to tell us about the problem
beforehand and we're trying to solve this in a reliable way.

Rob


OK, bigger pictures at:
http://www.scoobysworkshop.com/2005p...Connectors.jpg
http://www.scoobysworkshop.com/2005p...erTankDone.jpg

Hmmm, looks like no bosses...just threaded into the tank with a sealer
and cinched up with a nut. Is there also a pickup screen on the
inside of the tank, connected to the AN angle fitting? How about a
low point quick drain? Might be a good idea.

You could use a hole saw to cut an access hole that could later be
closed using an expanding, fuel resistant "Thermos style" pressure
cap. Four different sizes at Wicks Aircraft. The 2" TURN-TITE FUEL
CAP looks to be the most secure.
http://www.wicksaircraft.com/catalog...301/index.html
Then you could fish a straight AN bulkhead fitting like this:
http://www.wicksaircraft.com/catalog...955/index.html
with an O-ring on it down a wire and pull it out far enough to get a
bulkhead nut on it.

You should provide some means of inspecting or cleaning out the inside
of the tank anyway.

D.Anderson

Good advice, thanks everyone!

The tank already has a low point drain connection which attached to a drain
valve. Construction is the same brass insert. There's no pickup screen on
the AN fitting, it's again the same brass insert with a standard AN
connection screwed in.

As you can (barely) tell from the picture, there's also two connections on
the righthand side. The top one is unused. The bottom one fits a 'low fuel'
level detector. Plenty of holes, but none large enough to do much fishing.
Anyway, I have plenty of options to explore from this thread, thanks again
everyone.

Rob