Patent ID: 8226123

Claim:
A fuel tank comprising: a tank shell having a bottom and a bight in the bottom, the bight providing a riser within an interior of the fuel tank, the riser creating a primary sump and a secondary sump, the primary and secondary sumps conjoining in a space of the fuel tank higher than the riser; a first vent valve venting the fuel tank, the first vent valve being configured to be closed when a level of fuel in the primary sump is equal to or higher than a first predetermined filling level that is lower than the riser; and a second vent valve venting the fuel tank, the second vent valve being configured to be closed when a level of fuel in the secondary sump is equal to or higher than a second predetermined filling level that is lower than the riser, wherein the first and second vent valves are arranged such that a volume of air or vapor dome within the fuel tank when full is equal to or greater than a prescribed volume of air or vapor dome needed to maintain a prescribed capacity of the fuel tank when full.