Spirometer techniques for measuring molar composition in argon carbon dioxide mixtures

Abstract

This paper examines a new technique for measuring gas composition through the use of a spirometer. A spirometer is high precision pressure transducer which measures the speed of sound in a gas through the emission and reception of ultrasonic pulses, commonly used in medicine to measure patient lung capacity. The spirometer was successfully calibrated to measure gas composition to an accuracy of 1.75% ± 1.23% by ratio by weight. By using a spirometer, the speed of sound was measured for a trapped volume of Argon CO₂ mixtures at ratios of 80 : 20, 85 : 15, 90 : 10, 95 : 5, and 100 : 0. The temperature dependence of the transit time was observed to behave according to the Laplace Formula, except for the presence of dramatic drops that were dependent on the Argon concentration. An argument is presented that these drops are technical limitations of the spirometer.