Patent Document ID: 20030212496
Application ID: 10401206
Patent Flag: 0

Claim One:
1. A method of determining the nitrogen concentration in a gas mixture whose carbon dioxide concentration is known, comprising the steps of: storing a database representing a number of gas mixtures whose molecular weights and carbon dioxide and nitrogen concentrations are known; modeling the molecular weight of a gas mixture as a function of the speed of sound in the gas mixture, the carbon dioxide concentration, and the nitrogen concentration, and a set of constant values, thereby obtaining a model equation; at a first temperature and pressure state of the gas mixture: measuring the speed of sound in the gas mixture, determining the constant values for the gas mixture from the database, and substituting these values into the model equation, thereby obtaining a first equation for the molecular weight of the gas; at a second temperature and pressure state of the gas mixture: measuring the speed of sound in the gas mixture, determining the constant values for the gas mixture from the database, and substituting these values into the model equation, thereby obtaining a second equation for the molecular weight of the gas; and solving the two equations for the nitrogen content of the gas mixture.