Abstract: A method is provided for determining, prior to initiating filling of a fuel tank, the volume of the fuel tank that does not contain liquid, the method comprising the steps of: placing a vapor supply conduit in sealing relationship to the fuel tank; injecting a known volume of vapor through the vapor supply conduit into the fuel tank; measuring the amount the known volume of vapor increases the pressure of the fuel tank; and determining the volume of the tank that does not contain liquid from the known volume of vapor, and the measured amount of pressure increase. In preferred embodiments this method also determines if the fuel tank is equipped with a canister for removal of hydrocarbons from vapors displaces by fuel, and if the fuel tank has a leak by analysis of the rate at which pressure decreases after injection of the vapor. The method is also preferably used as a step in a method of automated refuelling of a vehicle.

Abstract: A method and apparatus is provided for determining if a vehicle with an operating engine is at a particular location, the apparatus comprising: an antenna comprising a continuous wire formed into at least one loop; and a means to determine when the antenna is exposed to an oscillating electromagnetic field having a frequency between about 700 and about 2100 Hz of a strength characteristic of a vehicle's alternator operating in the vicinity of the antenna. In a preferred embodiment of the present invention, the sensor of the present invention further comprises a means to generate a signal when the antenna is exposed to the oscillating electromagnetic field having a frequency between about 700 and about 2100 Hz of a strength characteristic of a vehicle's alternator operating in the vicinity of the antenna, and the signal is used as an input into a logic system that requires that the signal not be generated in order for a refuelling system to refuel a vehicle in the vicinity of the antenna.

Abstract: A fuel dispensing nozzle is provided, the fuel dispenser comprising: a) a vapor recovery conduit effective to provide communication between a vapor space of a fuel tank to be refuelled and a system to remove vapors displaced by fuel added to the tank; b) a fuel supply conduit; c) a sealing device effective to mate in a sealing relationship with a fuel tank inlet; d) an optical liquid sensor within the vapor recovery conduit that is effective to generate a control signal when liquid is detected within the vapor recovery conduit; and e) a device to disenable fuel flow when a control signal is generated by the optical liquid sensor. Also, the fuel dispenser comprises a sealing device that comprises a device to determine if a sealing relationship exists between the fuel dispenser and the fuel tank inlet.