202 • Appendix G: Infrared Sensors
GX-6000 Operator’s Manual
IR CO
2
Start Up and Normal Operation
For instructions to startup and use a GX-6000 that includes an infrared CO
2
sensor,
reference “Start Up” on page 25, “Measuring Mode, Normal Operation” on page 35, and
“Measuring Mode, Alarms” on page 41. Follow these instructions keeping the following
special considerations in mind:
•
A background level of CO
2
exists in fresh air. Table 25 below indicates a typical gas
reading in fresh air.
•
When you perform a demand zero during start up, operation, or calibration, you must
use the CO
2
scrubber provided with the instrument to remove background CO
2
from
the air being sampled. See “Performing a Demand Zero for Carbon Dioxide Sensors”
below.
If you have a PID sensor in your instrument, see “Performing a Demand Zero for
Instruments with a Carbon Dioxide Sensor and a PID Sensor” on page 203.
•
Since there is a background of CO
2
in air, do not use the
AUTO ZERO
feature that
can be turned on and off in Maintenance Mode. The factory setting for the feature is
OFF
.
Performing a Demand Zero for Carbon Dioxide Sensors
When setting the zero reading, the carbon dioxide scrubber shipped with the GX-6000
allows you to eliminate carbon dioxide normally found in fresh air. To perform a demand
zero, do the following:
1 . Remove the tubing from the side of the scrubber that does not have an arrow pointing
to it.
2 . Connect the tubing to the GX-6000’s inlet fitting. Be sure the arrow on the filter is
pointing toward the inlet fitting.
Figure 45: CO2 Scrubber Connected to GX-6000
3 . Wait one minute for the fresh air sample to flow through the carbon dioxide scrubber,
then press and hold the
▲
AIR button to set the zero reading.
4 . Remove the scrubber from the inlet fitting.
Table 25: Carbon Dioxide Fresh Air Readings
Sensor Range
Approximate Fresh Air
Reading
0 - 10 %vol
0.04 %vol
0 - 10,000 ppm
400 ppm
To GX-6000
CO2 Scrubber
