YOKOGAWA SC150, Instruction Manual

Page: 43 / 58

IM 12D7B4-E-H
37
Calculation example
Calculate the temperature co-efficient 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.
Set the temperature coefficient in the SC150 converter.
147.6 - 124.5
x 100= 1.298 %/C
α
=
124.5(31.0 - 25) - 147.6(18.0 - 25)
Where t
1
, t
2
: liquid temperature (°C)
K
1
: conductivity at t
1
(°C)
K
2
: conductivity at t
2
(°C)
K
2
K
1
K
ref
T
2
T
1
T
ref
T [ºC]
K
[
µ
S
/c
m
]
Fig. 11-1. Conductivity
B. Calculation of Temperature Coefficient 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 coefficient set to 0,00%/°C and use the
following equation to calculate a temperature coefficient (
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
2
- T
ref
))
K
1
+
α
( T
2
- T
ref
) - K
2
+
α
( T
1
- T
ref
) = K
2
- K
ref