SCHOTT ProLab 4000, Operating Manual

Page: 157 / 228

ProLab 4000 Conductivity
157 ba75646d03 12/2012
10.3 Determining the cell constant (calibration in control
standard)
Why determine the cell
constant?
Due to aging, the cell constant slightly changes. As a result, an inexact
measured value is displayed. Calibration determines and stores the
current value of the cell constant.
Thus, you should calibrate at regular intervals. The calibration data of
non-ID sensors is stored in the meter. For ID sensors, the calibration
data is stored in the sensor.
You can determine the cell constant of the conductivity measuring cell
in the ranges 0.450 ... 0.500 cm
-1
, 0.585 ... 0.715 cm
-1
or 0.800 ... 1.200
cm
-1
by calibrating in the 0.01 mol/l KCl control standard or set it man-
ually in the range 0.250 ... 2.500 cm
-1
or 0.090 ... 0.110 cm
-1
.
Besides, the fixed cell constant 0.010 cm
-1
can be selected.
In the delivery condition, the calibrated cell constant of the meters is set
to 0.475 cm
-1
(conductivity measuring cell LF413T(-ID).
CalClock The expiry of the CalClock reminds you to clean the measuring cell. It
is still possible to measure.
The CalClock is set to 180 days in the factory. You can change the
interval (see page 142).
Stability control During calibration, the stability control is automatically activated.
Display of calibration
data and download to
interface
You can display the data of the last calibration (see page 168 and
page 160). Subsequently, you can transmit the displayed calibration
data to the interface, e. g. to a PC, with the
<PRINT> key.
Note
The calibration record is automatically transmitted to the interface
after calibrating.