30
3.
Enter the engineer menu (procedure given at Appendix 2, Figure 15),
highlight CALIBRATE, long press ENTER button for 8 seconds to enter the
next menu.
Figure 17
Highlight STANDARD GAS and adjust the value to that of the concentration of
CO
2
standard gas. If the standard gas concentration precision is to 2 decimal
places numbers round up accordingly.
Then highlight CAL-BEGIN and long press the ENTER button for 8 seconds,
at the same time, open the standard gas as set per Figure17 and the device
will begin to calibrate. The screen will display the message ‘ADJUSTING!’ as
sown in FIGURE 18.
Figure 18
The thick cross bars in the display will be erased as time passes and the
calibration will end when they are completely erased. If the calibration is
successful, the menu will show ADJUST OK and subsequently exit into