wrote in message
oups.com...
It does provide good venting of
the tank. It does have a drawback in that if the tanks are full and
the plane is slightly wing low (sitting with the wing wheel on, for
example), water will tend to siphon from the low wing out the vent
hole. This vent is about 5/16th diameter on my Zuni.

Steve,
I should maybe manifold all three lines at the turtle deck that would
prevent siphoning.
I believe also the 5/16" vent tube will be enough, as each tank is
relatively
small and all will have a separate dumb valve.
The centre tank is 2 x 8 gal. front 2x 6 and the back 2x5gal.

one or two foam ribs outboard of the root rib. The intent of
this system was to keep the water plumbing all in/on the wing. That
way, there would be no leaks into the fuselage.
Is this similar to what you are planning to do, but with one
tank ahead of and one behind the spar?

I was planning on placing the valves in the front and back tank
and stay with a standard 2 ball valve set-up for the spar tank.
Tank you
Udo