System and method for testing fuel tank integrity

Abstract

The invention relates generally to a system and method for testing fuel evaporative systems, and more particularly to a stand-alone tank tester system (and method) for testing vehicle fuel tank integrity. Furthermore, a self-contained calibration tank with switchable leak sizes for calibrating the tank tester to multiple leak sizes is provided. Constant flow and vacuum methods for testing fuel tank integrity are also provided.

1 . A method for calculating the vapor space inside a fuel tank, comprising: 
 pressurizing the fuel tank to a predetermined pressure level;    decreasing the pressure in the fuel tank at a known rate;    calculating a vapor space measurement of the fuel tank, wherein the vapor space measurement is a function of time required for the fuel tank to depressurize at the known rate.    
     
     
         2 . A method for calculating the vapor space inside a fuel tank, comprising: 
 applying a flow of gas to a fuel tank at a predetermined rate;    ceasing the flow of gas when pressure inside the fuel tank achieves a predetermined level;    measuring an elapsed time between the application of the flow of gas and the achievement of the predetermined pressure level; and    calculating a vapor space measurement for the fuel tank, wherein the vapor space measurement is a function of the predetermined rate and the elapsed time.