YOKOGAWA SC450G - Page 68

IM 12D08N05-01E
APP-2
<APPENDIXES>
B. Calculationoftemperaturecoefcientfactor(withtwoknownconductivity
values at different temperatures)
Measure the conductivity of the liquid at two temperatures, one below the reference and
abovethereferencetemperaturewiththetemperaturecoefcientsetto0,00%/°Canduse
thefollowingequationtocalculateatemperaturecoefcient(α).
K
T
K
ref
=
1+α ( T - T
ref
)
K
2
- K
1
α
=
K
1
( T
2
- T
ref
) - K
2
( T
1
- T
ref
)
K
1
K
2
K
ref
=
=
1+α ( T
1
- T
ref
)
1+α ( T
2
- T
ref
)
K
1
(1 + α ( T
2
- T
ref
)) = K
2
(1 + α ( T
1
- T
ref
))
K
1
· α ( T
2
- T
ref
) - K
2
· α ( T
1
- T
ref
) = K
2
- K
1
Where T
1
, T
2
:liquidtemperature(°C)
K
1
:conductivityatT
1
(°C)
K
2
:conductivityatT
2
(°C)
Figure 1 Conductivity
Calculationexample
Calculatethetemperatureco-efcientofaliquidfromthefollowingdata.
Conductivity124.5µS/cmataliquidtemperatureof18.0°Candaconductivity147.6µS/
cm at a liquid temperature of 31.0 °C.
Substituting the data in the above formula gives the following result.
147.6 - 124.5
x 100= 1.298 %/C
α =
124.5(31.0 - 25) - 147.6(18.0 - 25)
SetthetemperaturecoefcientintheSC450Gconverter.