IM 12D08N05-01E
APP-1
<APPENDIXES>
APPENDIXES
Appendix 1 Temperature compensation
The conductivity of a solution is very dependent on temperature. Typically for every 1°C
change in temperature the solution conductivity will change by approximately 2%. The
effect of temperature varies from one solution to another and is determined by several
factors like solution composition, concentration and temperature range. A coefficient (α) is
introduced to express the amount of temperature influence in % change in conductivity/°C.
In almost all applications this temperature influence must be compensated before the
conductivity reading can be interpreted as an accurate measure of concentration or purity.
n
NaCl or standard temperature compensation
From the factory the SC450G is set with the default of a general temperature
compensation function based on a Sodium Chloride solution. This is suitable for many
applications and is compatible with the NaCl compensation functions of typical laboratory
or portable instruments. SC temperature compensation.
Table 1
NaCl-compensation according to IEC 60746-3 with Tref = 25 °C
T
Kt
α
T
Kt
α
T
Kt
α
0
0.54
1.8
60
1.76
2.2
130
3.34
2.2
10
0.72
1.9
70
1.99
2.2
140
3.56
2.2
20
0.90
2.0
80
2.22
2.2
150
3.79
2.2
25
1.00
―
90
2.45
2.2
160
4.03
2.2
30
1.10
2.0
100
2.68
2.2
170
4.23
2.2
40
1.31
2.0
110
2.90
2.2
180
4.42
2.2
50
1.53
2.1
120
3.12
2.2
190
4.61
2.2
2.2
200
4.78
2.2
n
Configure calculated temperature coefficient (TC).
Follow routing
Commissioning >> Measurement setup >> Temp.compensation >> T.C.
Enter the temperature coefficient calculated from the following formula:
A. Calculation of temperature coefficient factor (With known conductivity at
reference temperature).
K
t
- K
ref
α
=
T - T
ref
100
K
ref
X
α = Temperature compensation factor in %/°C
T = Measured temperature in °C
K
t
= Conductivity at T
T
ref
= Reference temperature
K
ref
= Conductivity at T
ref
