| 摘要 |
<p>1530922 Gas analysis UNITED TECHNOLOGIES CORP 18 Dec 1975 [19 Dec 1974(2)] 51953/75 Heading G1A A system for measuring the amount of contaminant in a sample gas comprises a gas sample cell 28 and a cell 34 containing a reference gas, means for alternately filling cell 28 with ambient air or sample gas, means 104, 106 for producing and means 112, 110 (also Fig. 4) for moving an infrared beam and passing it alternately through the cells, detector means 128 with narrow band filters producing two electrical sgnals indicative of infrared absorbtion in the respective cells, both when the sample cell is filled with ambient air and with sample gas, means including a signal processing unit 33 for producing therefrom a signal proportional to the concentration of the contaminant in the sample gas. As notch 144 passes LEDs 146, 148, 150 and phototransistors 152, 154, 156 they provide synchronization pulses to processing electronics 33 on lines 36a, b and c. Those on line 36b are applied to FET 197 Fig. 19 so that line 196 is referenced to earth via resistor 198 to restore the D.C. component to the above signals. With two narrow band filters in detector means 128 sample and reference output signals are obtained from electronics 33 on lines 180, 182, 180' and 182' for CO and hydrocarbon respectively. These pass to a data analysis system 24 having a multi-plexing unit and a computer which computes V R AIR x V S GAS and V S AIR x V R GAS where VR and V S are voltages due to the reference and sample cells and AIR or GAS refers to whether the sample cell is filled with air or gas. The computer output i which is equivalent to the amount of CO or hydrocarbon. Details of system 24 are described with Figs. 10 and 11 (not shown), and an analogue version with Fig. 15 (not shown). The output is compensated according to a predetermined function as for example that in Fig. 13. The embodiments are the same as in Specification 1530923.</p> |
