| 摘要 |
PROBLEM TO BE SOLVED: To provide a measuring device and a measuring method capable of measuring the trace oxygen concentration accurately by forming a calibration curve for oxygen concentration measurement in the ppb unit. SOLUTION: The accurate measurement is attained by setting the control voltage of a concentration detection cell in a comparatively high oxygen concentration range following surely the Nernst's equation in order to secure linearity of the relation between an output value of a limiting current type oxygen sensor and the oxygen concentration, installing a pump counter electrode in an exclusive air duct so that dipping is enabled from an electrode having a higher oxygen concentration when the oxygen concentration in measuring gas is below the control concentration, installing a concentration detection cell electrode and a pump cell electrode independently so as not to be influenced by a voltage drop or the like caused by a pump current, taking measures for removing the influence of interference gas such as coexisting combustible gas or the like, and integrating a means for enabling formation of the calibration curve for oxygen concentration measurement in the ppb unit into this measuring device. |
