Designation
Quantity
Measuring range
Units Resolution
1. Conductivity LF1 500 uS
B-01
DLF1
0...500.00 uS
0.01 uS
2. * Conductivity LF2 50 mS
B-02
DLF2
0...50.000 mS
0.001 mS
3. Conductivity LF3 500 mS
B-03
DLF3
0...500.00 mS
0.01 mS
Ranges can be deactivated by selecting stops '- - - - -' in the list.
Note: The measurable quantity can only be changed while sensor locking is disabled
(locking level 0).
8.3.2.Cell constant
The cell constant is the indicator used for conductivity measuring cells as determined by the
size and geometric arrangement of the measuring electrodes. It remains virtually unchan-
ged. So long as the electrode surfaces are clean and free of any insulating deposits calibra-
tion is generally not necessary. However, after cleaning, repair, or probe replacement it
may be necessary to correct the cell constant. It can then be reset as part of a calibration
process using reference solutions. The cell constant is preconfigured to the following valu-
es.
FYD741LFP: 0,500
FYD741LFE01: 0,550
Note: The cell constant can only be entered while sensor locking is disabled (locking level 0).
8.3.3.Setpoint
The probe adjustment method in which the cell constant is entered is generally less satisfac-
tory than the method of adjusting the measuring ranges on the basis of a reference solution.
In this method the conductivity of the reference solution is entered as setpoint and the probe
is then adjusted by pressing the '
ADJ
' key. In so doing the cell constant is reset based on
the quality of the reference solution.
Note: The probe can only be adjusted while sensor locking is disabled (locking level 0).
8.3.4.Temperature compensation
For this probe, under menu item 'Temp.Comp.', three different settings are available.
Temp. Comp.:
Off
No temperature compensation at low or very high conductivity values
Natural water Temperature compensation with non-linear characteristic for natural water and
high-purity water
Linear
characteristic
Temperature compensation with linear characteristic and settable temperature
coefficient
The linear temperature coefficient is entered in the next line
Temperature coefficient
1.90 %/K
If the temperature coefficient of a sample is not known, α can be defined experimentally.
We measure electrical conductivity values κ25 at (25 ± 0,1) °C and κT at a known tempera-
ture (T2 ± 0,1) °C; these values are then entered in the following equation
α
= (
κ
T
-
κ
25
) *
100% / κ
25
(T2-25)
eingesetzt.
If measuring is performed without temperature compensation, the conductivity measured at
a known temperature can be converted to 25 °C using a correction factor.
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