Hach si792 D series, User Manual

Page: 76 / 96

Calibration
74
8.1.2.2 Calibration in water
The water must be in equilibrium with air (percent saturation for water is
100%). The exchange between air and water is very slow. To speed up
the calibration, make sure that there is a steady flow during calibration.
1.
Press
CAL
, enter passcode:
1100
,
ENTER
. The display will briefly
show CAL and then the entered (or default) humidity value.
2.
Remove the sensor from the process and place in the calibration
water.
3.
Enter the actual relative humidity (for water always 100% relH) and
press
ENTER
. The display will show the entered (or default)
barometric pressure.
4.
Enter the barometric pressure and press
ENTER
. A drift check will
begin. The drift check may take some time. When complete, the
display will show the concentration in the units specified in the
configuration menu.
Note: To exit the drift check after > 10 seconds, press CAL
(accuracy will be reduced).
5.
Accept the calculated value for the concentration or adjust the value
as necessary and then press
ENTER
. The display will show the new
slope and zero (relative to 25 °C and 1.013 mbar).
6.
Press
ENTER
to end the calibration. Return the sensor to the
process. The measured value will be shown in the display
alternately with Hold.
7.
Press
ENTER
to return to the measure mode.
8.1.3 Gas calibration (volume concentration)
Make sure that GAS is selected in the configuration menu (
Table 9 on
page 36
).
1.
Press
CAL
, enter passcode:
1100
,
ENTER
. The display will briefly
show CAL and then the entered (or default) humidity value.