Fueling system vapor recovery and containment performance monitor and method of operation thereof
First Claim
1. A system for monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system with a vapor containment system, the fuel storage system providing fuel for dispensing by at least one fuel dispensing unit, comprising:
- a vapor pressure sensor operatively connected to the vapor containment system of the fuel storage system to measure the vapor pressure in the fuel storage system; and
a monitor operatively connected to the vapor pressure sensor wherein the monitor is adapted to;
detect 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;
monitor a vapor pressure level in the fuel storage system over a period of time to determine if the fuel storage system contains a leak;
determine 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, for which the monitor is further adapted to;
calculate 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;
calculate pressure mid points from the measurement pairs; and
use 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, andabort the monitoring of the vapor pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires.
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Accused Products
Abstract
A method and apparatus for monitoring and determining fuel vapor recovery performance is disclosed. The dispensing of liquid fuel into a tank by a conventional gas pump nozzle naturally displaces a mixture of air and fuel ullage vapor in the tank. These displaced vapors may be recovered at the dispensing point nozzle by a vapor recovery system. A properly functioning vapor recovery system recovers approximately one unit volume of vapor for every unit volume of dispensed liquid fuel. The ratio of recovered vapor to dispensed fuel is termed the A/L ratio, which should ideally be approximately equal to one (1). The A/L ratio, and thus the proper functioning of the vapor recovery system, may be determined by measuring liquid fuel flow and return vapor flow (using a vapor flow sensor) on a nozzle-by-nozzle basis. The disclosed methods and apparatus provide for the determination of A/L ratios for individual nozzles using a reduced number of vapor flow sensors. The disclosed methods and apparatus also provide for the determination of fuel dispensing system vapor containment integrity, and the differentiation of true vapor recovery failures as opposed to false failures resulting from the refueling of vehicles provided with onboard vapor recovery systems.
159 Citations
10 Claims
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1. A system for monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system with a vapor containment system, the fuel storage system providing fuel for dispensing by at least one fuel dispensing unit, comprising:
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a vapor pressure sensor operatively connected to the vapor containment system of the fuel storage system to measure the vapor pressure in the fuel storage system; and a monitor operatively connected to the vapor pressure sensor wherein the monitor is adapted to; detect 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; monitor a vapor pressure level in the fuel storage system over a period of time to determine if the fuel storage system contains a leak; determine 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, for which the monitor is further adapted to; calculate 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; calculate pressure mid points from the measurement pairs; and use 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, and abort the monitoring of the vapor pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification