In a message dated 10/03/98 08:27:38, jnaylor@avnet.co.uk writes:
<< running it up the forward face and then back into the fuel tank area to be
externally vented >>
The readings of the old sight gauge were often totally different from "true by
filling", as it was all too easy for a plug of fuel to get trapped out of
sight in the vent line, which in effect subtracts from the column. So one has
to be rather careful how the coupling into the airspace at the top of the tank
is made. a) if the tank is really full or overfull, there is no airspace, so
such a pipe will be flooded, though normality should prevail when the level
comes back below the vent pipe connection, providing the pipe steadily rises.
b) but probably worse, when the tank is near full, tilts in either plane,
and sloshing, will easily send plugs of fuel back into the top of the sight
tubes on top of a column of air. With a short external line entering the
top surface of the tank, it should be possible to see that any such plugs
have drained back into the column correctly.
Venting to the filler hose behind the tank (even if high enough to be in
guaranteed airpsace) is unfortunately out, as it would certainly get flooded
---From the wrong end durng filling. So perhaps a T some way up the tank vent
line would be best. Too far up and we are back again at the original design
!
If we all try somewhere different, perhaps an optimum answer will emerge !
Graham C G-EMIN
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