Tank Vapor Space & Fluid Management
Ullage (Vapor Space) Level Attainment
Spit-back/Well-back Control
This fill valve ball is set lower than
the vent valve ball but does not
close until the refueling vapors
are shut off by the vent valve.
This vent valve shuts off
the refueling vapors and
creates back pressure to
lift the fill valve ball into
place.
Fuel System
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