| 摘要 |
PURPOSE:To adjust the zero point and span of an ultrared gas analyzer, while flowing gases to be measured to a sample cell, by using an aptical attenuator of preset attenuation in a wavelength range other than the range to be measured. CONSTITUTION:There is interposed between a sample cell 2 and a detector 4 a narrow band pass filter 3 which allows the ultrared ray of the wavelength range having no absorption by the gases to be measured to pass therethrough. The ultrared ray coming from a light source 1 and passing through the cell 2 and the filter 3 is received by the detector 4, and the gain of an amplifier is so adjusted that the indication takes the maximum of the scale thereby to adjust the zero point. Then, an optical attenuator 4 having the same attenuation as the absorption of the ultrared ray due to the gases of 50 ppm is inserted into an optical path so that the quantity of the light received is measured by the detector 4 to determine the span of 0 to 50 ppm. After the span is determined as in the above, the filter 3 and the attenuator 5 are removed, and a filter allowing the absorption band range of the gases to pass therethrough is inserted into the optical path so that the concentration of the gases passing through the cell 2 may be measured (although requiring conversion). |
