Manually Set Zero

This procedure falls under the Measurement > Settings menu option:

1. Place potassium permanganate (KMnO₄) in Chamber Out.
2. Power on the instrument and allow adequate warm-up time (3 min).
3. Press the RIGHT arrow when Measure is highlighted to begin a measurement.
4. Let the sensor stabilize and automatically begin measuring.
5. Once the measurement begins, press the RIGHT arrow until you access the Settings menu.
6. Scroll down to Set Zero.
7. Press the RIGHT arrow to highlight C₂H₄.
8. Press Enter.
9. A message appears asking “zero selected sensors?”
   • Press Enter to confirm.
10. A message appears asking to “Place KMnO₄ in CH_Out.’”
    • If KMnO₄ is in Chamber Out, press Enter to confirm.
11. The display will switch to Monitor Mode and “correcting offset” is shown at the bottom.
    • The settings will automatically change to:
      • Chamber Out= On
      • Chamber In = Off
      • Closed Loop = On
12. The instrument will run for the amount of time set in the following menu: Setup > Calibration > C2H4 > Offset Correction. It is recommended to keep this setting at 10 minutes.
13. The instrument will make a “beep” sound twice to indicate that the offset correction is complete.
    • The instrument will return to Monitor/Graph Mode and “correcting offset” will no longer appear on the display when the zero calibration is complete.
14. The measurement will continue with the original settings for the conditioning chambers and Closed Loop on/off.

Figure 16: Measurement > Settings Menu display (left); flow path of internal gas stream (right).