Temperature compensation with table
The user can set up a table containing up to
ten value pairs for a special user-defined
medium so that the temperature dependence
of the temperature coefficient for any fluid can
be handled.
If the temperature coefficient for different
temperatures is known, the corresponding
values can be entered in the table. If the
temperature dependence of the medium is
not known, it first needs to be determined as
follows:
–
Select the temperature range in which the
measurement is to take place.
–
Take a sample of the process medium.
–
Measure the uncompensated conductivity
at different temperatures. Heat up the
sample slowly to do this. Determine the
uncompensated conductivity at different
temperatures.
–
The
α
value which corresponds to the
temperature and the conductivity value is
determined using the following formula:
α
(x)
=
T
(x)
=
The values thus calculated are entered in the
table.
(
1) 100
1
2
k
k
T
T
− ⋅
−
2
1
T
T
1
2
2
+
TAB01.CDR
T
1
T
(x)
T
2
T
k
1
k
2
k
(x)
Fig. 5.14
Determination of
temperature coefficient
α
(x)
TAB02.CDR
T
1
T
2
T
3
T
4
T
(x)
α
4
α
3
α
2
α
1
α
(x)
Fig. 5.15
Entry of table values with
calculated
α
(x)
LM253E5C.CHP
Liquisys M CLM 223 / 253
Instrument configuration
Hauser
43