Vaisala GMT220 - Manual (Page 31)

Chapter 5 ______________________________________________________________ Maintenance
VAISALA _______________________________________________________________________ 31
0505-236
Figure 11 Location of the GM70 Adjustment Button
6. Press OK to confirm the adjusting.
7. Select CO2 , press SELECT.
8. Press YES to give the ambient pressure and temperature values.
To continue adjusting press EXIT .
9. Now the adjustment mode is on. Press GRAPH to confirm that the
readings have stabilized. Go back and press ADJUST to select the
adjustment method.
10. Select 2-point adjustment , press SELECT . Press READY with the
stabilized reading in the lower reference concentration.
11. Give the lower reference concentration value by using the arrow
buttons (for example, if you are using pure nitrogen, enter value 0
ppm). Take care that you give the correct value in correct units, as
you cannot revert the earlier values after accepting the new values.
Press
OK .
Next move on to the adjustment at the second (high-end)
reference point.
12. Take out the tubing from the low-end gas bottle and connect it to
the high-end gas bottle.
13. Let the high end reference gas flow and stabilize with a flow rate of
0.6 l/min. Follow the reading of GM70, and after it has stabilized,
wait for 6 more minutes.
14. Press READY with the stabilized reading in the higher reference
concentration.
15. Give the high-end reference concentration value by using the arrow
buttons. The analyzed CO
2
concentration of the reference gas is
typically printed on the bottle.
Take care that you give the correct value in correct units, as you
cannot revert to the earlier values after accepting the new values.
Press
OK .