Method and apparatus for measuring evaporative emissions in a

Abstract

Provided is a method and apparatus for measuring evaporative vehicle emissions in a fixed-volume enclosure. The method comprises the steps of providing a volume compensation means in fluid communication with a test chamber for compensating for changes in the test chamber fluid volume, where n is a positive integer, measuring the temperature of the test chamber fluid at the sample times t.sub.n, measuring the absolute fluid pressure of fluid at the sample times t.sub.n, determining the density of the evaporative emissions and the test chamber fluid at selected sample times t.sub.n, determining the mass of evaporative emissions present in the chamber, determining the theoretical volume change of the test chamber fluid at said sample times t.sub.n in accordance with the Ideal Gas Law (PV=nRT), determining the mass of the evaporative emissions in aspirated volume, summing the determined masses of the evaporative emissions to provide a calculation of the evaporative emissions aspirated by the volume compensation means during expansion of the test chamber fluid, and summing this with the final sample mass to determine the total evaporative emissions from a vehicle. In an alternative embodiment, a plurality of impingers are also provided for use in determining the aspirated mass of alcohol emissions in flexible fueled vehicles.