G 1400 series
Measurement Basics | 5
B-H87.0.0X.DK2-3.0
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5.5
Temperature compensation
The conductivity of aqueous solutions is temperature-dependent. The temperature
dependency varies greatly according to the type of solution. With temperature
compensation, the solution is calculated back to a uniform temperature in order to
compare it independently of the temperature. The normal operating temperature for
this is 25 °C. However, it can also be adjusted to 20 °C.
5.5.1
NLF temperature compensation according to EN 27888
For most applications, such as fish husbandry applications and measurement of
surface water and drinking water, non-linear temperature compensation for natural
water NLF is sufficiently accurate in accordance with EN 27888.
The normal operating temperature is 25 °C.
The recommended application range of NLF compensation is between 60 μS/cm and
1000 μS/cm.
5.5.2
Linear temperature compensation LIN
(only available at G 1420)
If the function of the temperature compensation is not known exactly, a linear
temperature compensation is normally adjusted in the device.
Open the Configuration menu and select the parameter
TCOR
. Configuration parameter
LIN
and
TLIN
correspond to TK
lin
.
Put simply, this means that the temperature dependency is approximately the same
over the considered concentration range of the solution.
Temperature coefficients of 2,0 %/K are most common.
Formula LF
Tref
= LF
TX
/ ((1 + TK
lin
/ 100%) * (TX - T
ref
))
A temperature coefficient can be determined, for example, with measurement of a
solution at 2 temperatures, T1 and T2, with temperature compensation switched off.
Formula TK
lin
= ((LF
T1
- LF
T2
) * 100%) / ((T1
– T2) * LF
T1
)
TK
lin
= value is entered in the Configuration menu in parameter
TLIN
.
LF
T1
= conductivity at temperature 1
LF
T2
= conductivity at temperature 2
5.5.3
Compensation of weak NaCl solutions
(only available at G 1420)
Compensation of weak NaCI according to EN 60746-3 solutions in pure and ultrapure
water
