Tank fittings

[Jesse Jenks]

I want to run an internal vent line from the root rib to the outboard
forward corner (high point) of my fuel tanks. As discussed by Ken, he used
an extra W-159 flange on the inside on the inside of the root rib. I was
thinking of just using AN bulkhead fitting through the root rib.
What arrangement of fittings do you use on the outside of the upper sight
guage tank outlet to connect to the cross vent, the inverted J vent, and the
sight tube? It would either require a cross fitting or two T fittings as far
as I can tell.
New to plumbing
Thanks.
Jesse





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[Ken]

Jesse Jenks wrote:

I want to run an internal vent line from the root rib to the outboard
forward corner (high point) of my fuel tanks. As discussed by Ken, he used
an extra W-159 flange on the inside on the inside of the root rib. I was
thinking of just using AN bulkhead fitting through the root rib.

I was not brave enough to try that. Seems to me that it would be very
easy to break the proseal and have a leak just from tightening the fittings.

What arrangement of fittings do you use on the outside of the upper sight
guage tank outlet to connect to the cross vent, the inverted J vent, and the
sight tube? It would either require a cross fitting or two T fittings as far
as I can tell.
New to plumbing
Thanks.
Jesse

The recommended practice is an elbow at the top of the sight tube and a
separate tank fitting (W-159) for the vent. There is a bulletin and also
discussion on this in archives although I don't know what the newer
manual says. There is several inches of space between the wing root and
the fuselage of course.

Then you need one 'T' at the bottom of the inverted 'J'. The T will be
available in female pipe threads for use with hose barbs for plastic
cross vent tubes, or flare connections for aluminum cross vent tubes. I
assume you want a flare on the vertical connection to the 'T'.
Ken




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[Jesse Jenks]

Ken,
OK so not a good idea to use a bulkhead fitting in the tank.
If I understand what you are saying I should have separate tank outlets for
the vent line and the upper sight gauge line? I would then put a T fitting
in the vent outlet, and an elbow in the upper sight gauge outlet? This would
make for a total of 4 outlets in the root rib, including the lower sight
gauge outlet, and the fuel feed outlet.
Why not just have one outlet for the vents and upper sight gauge and use a
cross fitting there for a total of 3 outlets in the root rib?
Also, do you stay with 3/8" aluminum fuel line for the vents and into the
sight gauge (just the short piece from tank to cabin), or use 1/4" in those
areas?
Thank you
Jesse

From: Ken <klehman@albedo.net>
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: Re: Tank fittings
Date: Fri, 19 Aug 2005 09:35:58 -0400

Jesse Jenks wrote:

I want to run an internal vent line from the root rib to the outboard
forward corner (high point) of my fuel tanks. As discussed by Ken, he

used

an extra W-159 flange on the inside on the inside of the root rib. I was
thinking of just using AN bulkhead fitting through the root rib.

I was not brave enough to try that. Seems to me that it would be very
easy to break the proseal and have a leak just from tightening the
fittings.

What arrangement of fittings do you use on the outside of the upper sight
guage tank outlet to connect to the cross vent, the inverted J vent, and

the

sight tube? It would either require a cross fitting or two T fittings as

far

as I can tell.
New to plumbing
Thanks.
Jesse

The recommended practice is an elbow at the top of the sight tube and a
separate tank fitting (W-159) for the vent. There is a bulletin and also
discussion on this in archives although I don't know what the newer
manual says. There is several inches of space between the wing root and
the fuselage of course.

Then you need one 'T' at the bottom of the inverted 'J'. The T will be
available in female pipe threads for use with hose barbs for plastic
cross vent tubes, or flare connections for aluminum cross vent tubes. I
assume you want a flare on the vertical connection to the 'T'.
Ken




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[Ken]

Jesse Jenks wrote:

Ken,
OK so not a good idea to use a bulkhead fitting in the tank.
If I understand what you are saying I should have separate tank outlets for
the vent line and the upper sight gauge line? I would then put a T fitting
in the vent outlet, and an elbow in the upper sight gauge outlet? This would
make for a total of 4 outlets in the root rib, including the lower sight
gauge outlet, and the fuel feed outlet.
Why not just have one outlet for the vents and upper sight gauge and use a
cross fitting there for a total of 3 outlets in the root rib?

Hmmm I can't imagine why you'd want a cross fitting anywhere. I used 4
tank connections because I continued the vent line to the outboard front
corner of the tank. There could be slugs of fuel in that line and I
didn't want that to affect the sight guage. I may not have typed what I
meant on my last post but as long as you have a separate fuel outlet
completely separate from the sight gauge and vent, I imagine you can do
most anything you wish.

Also, do you stay with 3/8" aluminum fuel line for the vents and into the
sight gauge (just the short piece from tank to cabin), or use 1/4" in those
areas?

I'm using 1/4".
Ken





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[Jesse Jenks]

Ken,
I was thinking sight tube, cross vent, and inverted J vent. That's three
different paths, and if I only use one tank outlet for all three... that's
why I had the idea to use a cross fitting. I see what you mean about
possibly getting an incorrect indication in the sight tube if you had a slug
of fuel in the vent line. A good argument for putting an extra outlet in the
root rib, but shouldn't the level in the sight tube eventually equal what is
in the tank even if a slug of fuel comes into the top of the sight tube from
the vent line? If not then maybe I could make sure the top of the sight tube
is higher than the vent line so any fuel in the vent line won't go into the
top of the sight tube.
Jesse





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[Ralph Baker]

Jesse,
Take a look in the Aircraft Spruce and Wicks catalogs for the myriad
fittings available. Sort of a plumbing "Erector Set". Don't forget
that aircraft flares are 37 degrees, not automotive 45 degrees.
Ralph Baker



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[Jesse Jenks]

Thanks Ralph,
I have been looking in the ACS catalog, that's the problem.. too many
possibilities.
Jesse

From: "Ralph Baker" <rebaker@sc.rr.com>
Reply-To: <rebel-builders@dcsol.com>
To: <rebel-builders@dcsol.com>
Subject: tank fittings
Date: Mon, 22 Aug 2005 00:00:52 -0400

Jesse,
Take a look in the Aircraft Spruce and Wicks catalogs for the myriad
fittings available. Sort of a plumbing "Erector Set". Don't forget
that aircraft flares are 37 degrees, not automotive 45 degrees.
Ralph Baker



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