Measuring gas concn., esp. carbon di:oxide in mixtures - from variation in speed of sound at certain frequencies

摘要

Method and arrangement for determining the concn. of a gas in a mixt. of gases esp. for measuring the CO2 content, takes advantage of the increase in the speed of sound in some gases, at certain frequencies. This is detected by measuring the dispersion of sound in the mixt. in a dispersion zone to establish the dispersion This is then compared with dispersion curve for the pure gas. The speeds of sound outside the dispersion zone are also measured and compared for the pure gas and the mixt. Two different frequency sound waves of known phase relation are transmitted over a measurement path contg. the mixt. and their phase angle compared at the end of the path.