PURPOSE:To enable continuous measurement with high precision and durability by selectively burning only nonmethane hydrocarbon with the help of MnO2 as oxidation catalyst and seeking nonmethane hydrocarbon value after deduction of the methane portion from total hydrocarbon value. CONSTITUTION:Only nonmethane hydrocarbon of gas is selectively burned with the assistance of MnO2 as oxidation catalyst. Next, nonmethane hydrocarbon value is measured after deducting the methane portion from total hydrocarbon value of gas. It is recommended that alpha-MnO2 having specific surface area of more than 100m2/g, beta-MnO2 having specific surface area of more than 60m2/g, gamma-MnO2 having specific surface area of more than 40m2/g or the like be used as MnO2. Then, for instance, by switching from flow route (a) containing the oxidation catalyst layer A to flow route (b) not containing the oxidation catalyst layer or vice versa every few minutes, the concentrations of hydrocarbon contained in the both flow routes are measured by FID (hydrogen flame ionization) method. Thus the nonmethane hydrocarbon value is measured based on the difference between the both concentration values.
展开▼
