Vaisala HM70 - Manual (Page 65)

Chapter 12 ______________________________ Calibration and Adjustment of HM70 Series Probes
VAISALA _______________________________________________________________________ 63
11. Give the lower reference humidity value by using the arrow
buttons. Press
OK .
12. Set the probe to the higher reference humidity. Press READY
when the reading is stabilized. You can follow the stabilization
from the
GRAPH display.
13. Give the higher reference relative humidity value by using the
arrow buttons. Press
OK .
14. Confirm the adjustment, press YES (by pressing NO you
return to adjustment mode display and no changes are made). If
the difference between two references is less than 50 %,
adjustment can not be done.
15. Adjustment has been carried out. Press BACK to exit the
adjustment mode press EXIT to return to the basic display.
16. Replace the screw onto calibration button.
You can attach a sticker on the calibration button screw to seal the
calibration.
1-Point Adjustment
Usually it is recommended to make an adjustment in two reference
humidities. If adjustment is done by using one reference humidity (1-
point adjustment), select the reference humidity so that it represents
the measuring environment. Make the adjustment in one point as
instructed in the previous section 2-Point Adjustment (select
1-point
adjustment and follow the display instructions).
Temperature Adjustment
Temperature adjustment in one or two points can be done if there is
reason to believe that the adjustment is changed. If adjustment is done
only in one point, reference condition shall represent the measuring
environment.