Patent ID: 8327689

Claim:
A method of monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system with a fuel tank that provides fuel for dispensing by at least one fuel dispensing unit, comprising the steps of: measuring a pressure level in the fuel storage system using a pressure sensor operatively connected to the fuel storage system; detecting if all of the at least one fuel dispensing units are idle, and if all of the at least one fuel dispensing units are idle, monitoring the pressure level in the fuel storage system over a period of time to detect if the fuel storage system contains a leak; determining a model to estimate a rate of change of pressure times ullage volume of the fuel storage tank in the fuel storage system for a given test pressure by: calculating a plurality of pressure rate and ullage volume measurement pairs each comprising an average pressure rate in the fuel storage tank using the pressure sensor, and ullage volume of the fuel storage tank, for a plurality of intervals; calculating pressure mid points from the measurement pairs; and using the measurement pairs and pressure mid points with linear regression to create a model of the rate of change of pressure times ullage volume at selected test pressures, wherein the monitoring of the pressure level in the fuel storage system is aborted at any time that any of the at least one fuel dispensing units are not idle before the period of time expires.