Knick Stratos Pro A401B PH, User Manual

Page: 122 / 196

122
Zero Adjustment (ISFET)
This adjustment allows the use of ISFET sensors with differing nominal
zero (pH only). The function is available when Sensor selection = ISFET
has been set during configuration. Zero adjustment is disabled for any
other sensors.
The adjustment is made using a zero buffer (pH 7.00).
Permitted range for buffer value: pH 6.5 ... 7.5.
Temperature-corrected input. Maximum zero offset: ± 200 mV.
Display Action Remark
Select Calibration.
Press enter to proceed.
Ready for calibration.
Hourglass blinks.
Display (3 sec)
Now the device is in
HOLD mode.
Immerse sensor in a pH
7.00 buffer. Enter the
temperature-corrected
pH value in the range
6.50 to 7.50 using the
arrow keys (see buffer
table).
Confirm with enter.
If the zero offset of
the sensor is too
large (> ± 200 mV),
a CAL ERR error
message is gener-
ated. In that case the
electrode cannot be
calibrated.
Stability check.
The measured value
[mV] is displayed.
The “hourglass” icon is
blinking.
Please note:
Stability check can
be stopped (by
pressing enter).
However, this re-
duces calibration
accuracy.
Zero adjustment