| 摘要 |
1,188,308. Infrared gas analysis. UNITED STATES STEEL CORP. Aug. 8, 1967 [Aug. 25, 1966], No.36395/67. Heading G1A. An infrared gas analyzer is calibrated periodicallyby the use of an automatic standardizer controlling the introduction of known standardizing gases into the analyzer and including means to vary the output of the analyzer amplifier, and a reference and sensing unit provided with a source of reference voltages and a comparator to compare the analyzer amplifier output with a reference voltage. The calibration is a two-stage operation. Firstly, a timer 28 in the standardizer 26 causes opening of a valve 16 to introduce into the analyzer a "zero" gas. This has a very low known proportion of a known gas and is used to calibrate the zero reading on the analyzer indicator 4 by automatic adjustment of a potentiometer 22A. The timer 28 also energizes relay 58 to close contact 58c and connect the references source 70 across the coils 46, 48 of the comparator 42, a dual bistable magnetic amplifier. The net ampere turns in coil 44 connected to the output of the analyzer amplifier, are connected with the sum of the ampere turns in coils 46 and 48 and depending on which is greater, a relay 72 or 76 is energized, causing motor 36 to drive potentiometer 22A in such a direction as to change the analyzer amplifier output and equalize the ampere turns in coil 44 with the sum of 46 and 48. The relay 72 or 76 is then de-energized. Valve 16 is then closed and valve 12 is opened to introduce "span" gas into the analyzer. This has a known proportion of known gas very near the maximum percentage reading on the indicator and thus is used to set the maximum indication value, this time by automatic adjustment of a potentiometer 24A. The timer energizes relay 54 to cause the reference source 70 to the connected only across coil 46. As before, either relay 72 and 74 are energized this time, to cause appropriate movement of potentiometer 24A acting on the amplifier 3 to equalize the ampere turns in coil 44 with those in 46. On equalization, the relay 72 or 74 is de-energized and the timer closes valve 16 and opens 8 to introduce the gas to be analyzed. |
