| 摘要 |
PURPOSE: To obtain a natural gas detector operable based on the absorbance of infrared-rays by determining a ratio signal between first and second absorption signals in response thereto. CONSTITUTION: The gas detector functions based on the absorption of the infrared-ray energy of a gas sample pressure fed through a gas sample chamber formed of a photocell 12. The gas sample is analyzed using the photocell 12 for measuring the path length of a gas sample beam, an infrared light source 14, and an infrared detector 16 interposed with a turnable chopper wheel 18. More specifically, the infrared detector 16 detects first and second measuring signals indicative of the first and second wavelengths absorbed by the gas sample and a ratio circuit 27 determines the ratio signal between the first and second absorption signals in response thereto. The ratio signal is fed to an analytical circuit 25 and a predetermined gas concentration level is reached, and alarm is delivered from an alarm circuit 33. |
