Patent ID: 7735365

Claim:
A method for measuring an amount of a substance depleted from a storage unit, the method comprising: supporting the storage unit on a vehicle; measuring a first weight of the storage unit and any liquid substance contained in the storage unit using at least two load-measuring devices; allowing a quantity of the liquid substance to be discharged from the storage unit; measuring a second weight of the storage unit and any liquid substance contained in the storage unit using at least two load-measuring devices; and determining the amount of liquid substance discharged or allowed to be discharged from the storage unit based on the first weight measurement and the second weight measurement; wherein the at least two load-measuring devices are configured such that at least one of a force or a moment measured by one of the at least two load-measuring devices, other than gravitational force of the storage unit and its contents, is reduced or cancelled by summation with forces or moments measured by the remaining of the at least two load-measuring devices.