| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure the concentration of nitrogen oxide in exhaust gas by surely reducing nitrogen dioxide in the exhaust gas to nitrogen monoxide.SOLUTION: A nitrogen oxide measuring instrument 1 is provided which comprises a sampling tube 2 for sampling exhaust gas and an analyzer 3 to which the exhaust gas sampled by the sampling tube 2 is introduced, for analyzing the concentration of nitrogen oxide in the exhaust gas. The sampling tube 2 includes a reduction sampling tube 2A having a reduction catalyst for reducing nitrogen dioxide in the exhaust gas to nitrogen monoxide, and an inactive sampling tube 2B that does not have reduction action. Either the exhaust gas sampled by the reduction sampling tube 2A or the exhaust gas sampled by the inactive sampling tube 2B is selectively introduced to the analyzer 3. |
