RKI Instruments GX-3R Pro - Page 75

75 • Chapter 5: User Mode and Calibration GX-3R Pro Operator’s Manual
5. Press and release POWER MODE. The example below shows the standard 4 sensors
(combustible gas, O
2
, CO, H
2
S).
6. Make sure the GX-3R Pro has been turned on for at least 45 seconds before continuing.
7. Press and hold AIR until the screen prompts you to release it.
8. If the fresh air adjustment passes, the instrument returns to the Gas Cal menu.
9. If the fresh air adjustment fails, “FAIL AIR” displays. Press and release POWER MODE to
acknowledge the failure. See “Troubleshooting” on page 118.
Performing a Zero Adjustment on the CO
2
Sensor
(CO2 ZERO CAL)
Performing a zero adjustment on the CO
2
sensor sets the sensor’s zero to a known concentration
of CO
2
(0 ppm or 0%).
Preparing for a CO2 ZERO CAL
To set the zero reading on the CO
2
sensor, you will need:
• 100% nitrogen (N
2
) cylinder
• 0.25 LPM fixed flow regulator
• Non-absorbent tubing
• Calibration cup
1. Confirm that the regulator knob is turned all the way clockwise. Screw the 0.25 LPM fixed
flow regulator onto the calibration cylinder.
MAINTE 7:49
20.9
O2 %
0 0 0.0
CH4 %LEL CO ppm H2S ppm
AIR CAL
MAINTE 7:49
HOLD AIR KEY
AIR CAL
MAINTE 7:49
ADJUSTING ZERO
RELEASE