Dostmann pH 7 Vio Manuel D'utilisation page 26

This device measures conductivity at real temperature (ATC or MTC) and then converts it to the reference
temperature using the correction factor chosen in program P3.4.:
Access this setup menu to set the temperature to which you want to refer the Conductivity
•
measurement.
The device can report conductivity from 15 to 30°C. By default, it is 25°C which is correct for most of
•
the analyses.
P3.4 Temperature compensation Factor
It is important to know the temperature dependence (% change in Conductivity per °C) of the sample
being measured.
• Access this menu to change the temperature compensation factor.
• By default, 1.91% / °C is set which is suitable for most of the analyses.
Press the key , the value flashes and as indicated by the icon
enter the new coefficient. Confirm with key
Compensation coefficients for special solutions and for groups of substances are shown in the following
table:
Solution
NaCl Saline solution
5% NaOH Solution
Diluted ammonia solution
10% Hydrochloric acid solution
5% Sulfuric acid solution
Compensation coefficients for calibration standards at different temperatures for T
shown in the following table:
°C 0.001 mol/L KCl (147µS)
0
1.81
15 1.92
35 2.04
45 2.08
100
2.27
To determine the calibration coefficient of a solution, the following formula is applied:
Where tc is the temperature coefficient to be calculated, C
(T1) and at temperature 2 (T2).
Each result with "correct" temperature is plagued by an error caused by the temperature coefficient. The
better the temperature correction, the lower the error. The only way to eliminate this error is not to use the
correction factor, acting directly on the sample temperature.
Select 0.00% / °C as the temperature coefficient to deactivate the compensation. The displayed
Conductivity value refers to the temperature value measured by the probe and not related to a reference
temperature.
Series 7 Vio ENG Version 2.0 April 2020
.
(%/°C)
2.12
1.72
1.88
1.32
0.96
0.01 mol/L KCl (1413 µS)
1.81
1.91
2.02
2.06
2.22
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( ���� − 25 ) − ����
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26
use the directional keys to
Solution
1.5% Hydrofluoric acid
Acids
Bases
Salts
Drinking water
25 ° C are
ref
0.1 mol/L KCl (12.88 mS)
1.78
1.88
2.03
2.02
2.14
����1
(���� − 25)
����2 1
are Conductivity at temperature 1
and C
T1 T2
(%/°C)
7.20
0.9 - 1.60
1.7 – 2.2
2.2 - 3.0
2.0
EN