| 摘要 |
<p>PROBLEM TO BE SOLVED: To easily perform the span calibration of an infrared gas analyzer at a low cost by imparting a prescribed chopping frequency to the infrared gas analyzer on the basis of the corresponding relation between a subject gas concentration and the chopping frequency. SOLUTION: A motor 1 is formed of, for example, a stepping motor, which rotates a sector 3. The sector 3 is a disc-like rotator having a slit or hole, which chops the infrared ray emitted from a light source 2. The infrared ray chopped by the sector 3 is passed through a cell 4 and detected by a detector 5. The cell 4 has a gas inlet port 4a and an outlet port 4b so as to carry a gas in the inner part. A zero gas is carried to the cell of an infrared gas analyzer to impart a chopping frequency corresponding to a prescribed gas concentration value A, and the input value S to the detector of the infrared gas analyzer at that time is measured. A subject gas is then carried to the cell in the state where the copping frequency is returned to a prescribed value to detect the input value M to the detector, and M×(A/S) is taken as the gas concentration after span calibration.</p> |
