Yokogawa EXAxt SC450 4-Wire Analyzer for Conductivity/Resistivity - Manual (Page 54)

46
IM 12D08N05-01E
Appendix 1
Temperature compensation
The conductivity of a solution is very dependent on temperature. Typically for every 1°C change in
temperature the solution conductivity will change by approximately 2%. The effect of temperature
varies from one solution to another and is determined by several factors like solution composi-
tion, concentration and temperature range. A coefficient (α) is introduced to express the amount of
temperature influence in % change in conductivity/°C. In almost all applications this temperature
influence must be compensated before the conductivity reading can be interpreted as an accurate
measure of concentration or purity.
NaCl or standard temperature compensation
From the factory the EXAxt is set with the default of a general temperature compensation function
based on a Sodium Chloride (table salt) solution. This is suitable for many applications and is com-
patible with the NaCl compensation functions of typical laboratory or portable instruments.
SC temperature compensation.
Table 11-1. NaCl-compensation according to IEC 60746-3 with Tref = 25 °C
Configure calculated temperature coefficient (TC).
Follow routing
Commissioning >> Measurement setup >>
Temp.compensation >> T.C.
Enter the temperature coefficient calculated from the
following formula:
A. Calculation of temperature coefficient factor
( With known conductivity at reference temperature).
K
t
- K
ref
α =
T - T
ref
100
K
ref
X
α = Temperature compensation factor in %/°C
T = Measured temperature in °C
K
t
= Conductivity at T
T
ref
= Reference temperature
K
ref
= Conductivity at T
ref
APPENDICES