Xylem COND3210 HANDHELD CONDUCTIVITY METERS - Manual (Page 34)

Operation Cond 3210
34 ba75794e01 01/2009
4.4.5 Determining the cell constant
(calibration in control standard)
Why determine the cell
constant?
Aging slightly changes the cell constant, e. g. by coatings. As a result,
an inexact measured value is displayed. The original characteristics of
the cell can often be restored by cleaning the cell. Calibration
determines the current value of the cell constant and stores this value
in the meter.
Thus, you should calibrate at regular intervals (we recommend: every
6 months).
Procedure You can determine the actual cell constant of the conductivity
measuring cell by calibrating with the control standard in the following
ranges:
z 0.450 ... 0.500 cm -1
(e.g. TetraCon 325, nominal cell constant 0.475)
z 0.800 ... 0.880 cm -1
(cells with a cell constant of approx. 0.840)
The cell constant is determined in the control standard, 0.01 mol/l KCl.
Cell constants outside the ranges quoted above cannot be calibrated.
In the delivery condition, the calibrated cell constant of the meter is set
to 0.475 cm
-1
(conductivity measuring cell, TetraCon 325).
AutoRead
(stability control)
The calibration procedure automatically activates the AutoRead
(stability control) function.
Display calibration data You can have the data of the last calibration displayed (see section
4.4.6).
Calibration evaluation After the calibration, the measuring instrument automatically evaluates
the current status of the calibration. The evaluation appears on the
display and in the calibration record.
Display Calibration
record Cell constant [cm
-1
]
+++ within the ranges
0.450 ... 0.500 cm
-1
or
0.800 ... 0.880 cm
-1
Error Error
outside the ranges
0.450 ... 0.500 cm
-1
or
0.800 ... 0.880 cm
-1
Eliminate the error according to
chapter 6 W
HAT TO DO IF ...