Sper Scientific 850045 Dissolved Oxygen - DO Pen - Manual (Page 6)

Perform the calibration procedure in an open and well
ventilated area to achieve the best possible results. Once
the calibration is complete the meter should read approx.
20.9 as this is the typical amount of O
2
in the air.
CALIBRATION
6
30
CAL Flashing
Counts down
from 30 to 0
6. Press and release the HOLD button (Fig., 1-3) - the
display will read HOLD.
7. Press and release the REC button (Fig., 1-4) - the
display will show a flashing CAL indicator and the upper
value will change to 30, then countdown to 0 (takes 30
seconds).
8. Once the countdown has been completed, the End
indicator will be displayed momentarily, then display will
return to the normal display as shown on page 3.