34 • Chapter 3: Operation
GX-6000 Operator’s Manual
Performing a Demand Zero
Before using the GX-6000, it is recommended to set the fresh air readings for the target
gases by performing a demand zero. This will set the CH
4
, H
2
S, CO, and PID channels to
zero and the OXY channel to 20.9%.
1 . Find a fresh-air environment. This is an environment free of toxic or combustible
gases and of normal oxygen content (20.9%).
2 . Turn on the unit as described above in “Turning On the GX-6000”.
3 . If you suspect any low-level VOC background in the area, you will need to use the
VOC zero filter.
NOTE:
If you have both a PID and a CO
2
sensor installed, you will need to follow the
directions in “Performing a Demand Zero for Instruments with a Carbon
Dioxide Sensor and a PID Sensor” on page 203 instead of following the
directions shown below.
a. Remove the plug from each end of the VOC zero filter.
b. Attach the VOC zero filter to the inlet fitting or probe. The filter does not have a
preferred flow direction.
c. Let the instrument draw through the VOC zero filter for 1 minute before
continuing.
4 . Press and hold the
▲
AIR button. The LCD prompts you to continue holding the
▲
AIR button and the buzzer will pulse while you hold the button.
5 . Continue to hold the
▲
AIR button until the LCD prompts you to release it. The GX-
6000 will set the fresh air reading for all channels. Start up is complete and the unit is
now ready for monitoring.
6 . If the VOC zero filter was used, remove the filter from the GX-6000’s inlet fitting or
probe. Reinstall the plugs on each end of the filter.
Turning Off the GX-6000
1 . Press and hold the POWER/ENTER button.
2 . TURN OFF will appear on the display and the buzzer will pulse for about five
seconds.
3 . Release the button when TURN OFF disappears from the display.