Endress+Hauser Liquisys M CLM253 - Setup 2 (Temperature)

Liquisys M CLM223/253 Commissioning
Endress+Hauser 39
7.4.2 Setup 2 (temperature)
Temperature coefficient α indicates the change in the conductivity per degree of
temperature change:
k(T) k(T )
0
(1+
=
(T - T ))
0
a
.
.
A0009163
Where
κ(T) = conductivity at process temperature T
κ(T
0
) = conductivity at reference temperature T
0
The temperature coefficient depends both on the chemical composition of the solution and
the temperature itself.
To determine the level of dependency, four different types of compensation can be selected
in the transmitter:
• Linear temperature compensation
• NaCl compensation
• NaCl ultrapure water compensation (neutral compensation)
• HCl ultrapure water compensation (acid compensation)
• Temperature compensation with table
Linear temperature compensation
The change between two temperature points is taken
to be constant, i.e. α = const. The α value can be edited
for linear compensation. The reference temperature
can be edited in the B7 field. The default setting is 25
°C.
1
a
T
k*
A0008945
 22 Linear temperature compensation
* Uncompensated conductivity
NaCl compensationIn the case of NaCl compensation
(as per IEC 60746), a fixed non-linear curve specifying
the relationship between the temperature coefficient
and temperature is saved in the device. This curve
applies to low concentrations of up to approx. 5 %
NaCl.
0
48
96
144
2.1
2.3
2.5
2.7
T [°C]
a [%/K]
A0008939
 23 NaCl compensation