| 摘要 |
A portable, infrared, multiple gas analyzer for measuring the concentration of a plurality of infrared absorbent gases with a simple optical arrangement for transmitting an infrared beam along an optical path along with gas mixtures to be analyzed. Light transmitting tubes arranged in a U-like configuration transmit infrared energy and the gases applied thereto over a small path to an infrared detector from an infrared source and provide electrical analog output signals representative of the detected gases. The detector output signals are processed by D.C. processing circuits including an analog to digital converter and microprocessing circuits for providing digital, binary coded, output signals representative of the detected gas concentration of the infrared absorbent gases. The analyzer can be readily calibrated by applying a non-infrared absorbent gas to the gas analyzer to provide a maximum output signal level with the infrared beam on and the background level or dark level signal with the beam off. The gas mixture having the infrared absorbent gases to be measured are applied to the analyzer for measurement and the resulting analog signals are amplified under control of a microprocessor for determining whether or not a preselected signal level stored in the microprocessor memory is exceeded or not. If not, the gain of the amplifier is increased to compensate for the aging of the analyzer. An offset voltage is applied to the analog to digital converter under control of the microprocessor to the amplified gas signals for increasing the resolution of the converter output signals only during the time intervals the absorbent gases are being measured. The microprocessor is programmed to execute a program for calculating the detected concentration of the gases undergoing analysis based on the previously acquired and stored "zero" gas level, dark level and known gas factors to provide the desired digital, binary coded, gas concentration signal from the analyzer.
|
