Page 122
IR Gas Calibration
UVTOCMaintenance.fm
Section 7
must be out. If the span gas is 10000 ppm CO
2
, LK1 must be in. See
Figure 51 on page 126.
Zero Adjustment
1. The Zero adjustment is made on the 8000 controller PCB, which is
mounted inside the front door of the electronics cabinet. Figure 47
illustrates the zero potentiometer adjustment. Turn the screw clockwise to
increase the voltage and counterclockwise to decrease the voltage.
After the zero gas reading has stabilized, adjust the Zero potentiometer
so that the voltage is between 0.26 and 0.27 V. 0.27 V will produce a CO
2
ppm reading slightly above zero. If the voltage is set at 0.25 V, a zero
reading would result, however you could not be certain if the gas ppm
reading was zero or below zero. The slight gas ppm increment above zero
ensures that you are in a positive range.
Figure 47 Adjusting the Zero Potentiometer on the 8000 Controller PCB
Span Adjustment
1. Connect the appropriate span gas (1000 ppm or 10000 ppm) to the IR
and let it flow for ten minutes at 200 cc/minute until the reading stabilizes.
2. After the reading stabilizes, adjust the span potentiometer to read the
approximate CO
2
ppm, either 1000 or 10000 ppm.
If the span gas does not yield 1000 ppm ± 5 ppm, or 10,000 ppm ± 50
ppm, verify the LK1 jumper position, see Figure 51 on page 126, and if
necessary contact your manufacturer representative.
Noise will create minor fluctuations in the readings, however if these
fluctuations bracket the desired values, they are acceptable.
IR cal 49.9C
17 ppm 0.26 V
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