26
Rev. 1 20.12.2019
EN
In a conductivity measurement the value shown on the display is the conductivity calculated at
the reference temperature. Then the effect of temperature on the sample is corrected.
When measuring pH, on the other hand, the pH value at the displayed temperature is shown on
the display. Here the temperature compensation involves adapting the slope and the electrode
offset to the measured temperature.
P3.3 Reference Temperature
Conductivity measurement is strongly related to the temperature.
If the temperature of a sample increases, its viscosity decreases and this leads to an increase in the mobility
of the ions and the measured conductivity, although the concentration remains constant.
For each conductivity measurement, the temperature to which it refers must be specified, otherwise value
obtained is meaningless. Generally, as temperature we refer to 25 ° C or more rarely to 20 ° C.
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°C to 30°C. By default, it is 25°C which is correct for most
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 analyses.
Press the key
, the value flashes and as indicated by the icon
use the directional keys
to enter the new coefficient. Confirm with
.
Compensation coefficients for special solutions and for groups of substances are shown in the following
table:
Solution
(%/°C)
Solution
(%/°C)
NaCl Saline solution
2.12
1.5% Hydrofluoric acid
7.20
5% NaOH Solution
1.72
Acids
0.9 - 1.60
Diluted ammonia solution
1.88
Bases
1.7 – 2.2
10% Hydrochloric acid solution
1.32
Salts
2.2 - 3.0
5% Sulfuric acid solution
0.96
Drinking water
2.0
