aerobat,
I would not put Tygon iside the fuel tank at all. It does not necessarily take a year for this stuff to get to be to stiff to enable the clunk to go to the bottom and top of the tank. Just for an example, I have a new ARF that has a pre-plummed tank. Without ever even having gas in the tank the clunk hangs in mid-air and does NOT settle to the bottom of the tank at all. I will be removing the tygon and replacing it with Hayes Neoprene with barbs and tie wraps and a stiffener to keep the line form falling forward like I have been doing with all my gassers.... Without the clunk going to the full top or bottom or sides of the tank how often do you think the clunk will be submerged in gas? Fix it right the first time. Planes are to expensive to be playing guessing games. Bill