Yokogawa SC72 Personal Handheld Conductivity Meter - Manual (Page 58)

IM 12D03D02-01E
7-3
7. Measuring Principles of this Instrument
7.3 Temperature Compensation and Finding Temperature
Compensation Coefficient
• Temperature Compensation
Table 7.1 shows the conductivity ratio at each liquid temperature when the conductivity
of a NaCl solution at 25
؇C is 1.
Table 7.1 Conductivity Ratios at Different Temperatures in
NaCl solutions
T0701.EPS
0.542 1 1.531
0
؇
C 25
؇
C 50
؇
C
2.103
75
؇
C
2.677
100
؇
C
As shown in the above table, liquid conductivity changes with liquid temperature. So, in
order to compare conductivities, conductivity values at a fixed liquid temperature are
needed. This SC72 meter includes standard temperature conversion functions, to display
a liquid conductivity value converted to 25
؇C, so this meter can be used for such
conductivity measurement comparisons. Temperature compensation coefficients of an
NaCl solution are stored in the SC72 meter. No other temperature coefficient setting is
required (for NaCl solutions).
Table 7.2 shows temperature coefficients of various electrolytic solutions.
Table 7.2 Temperature Coefficients of Electrolytic Solutions
T0702.EPS
Solutions
Lithium benzoate solution
Sodium acetate solution
Potassium chloride solution
Sodium hydroxide solution
Sulfuric acid
---
2.20
1.74
1.74
1.07
2.28
2.20
---
---
---
2.28
2.20
1.98
1.87
1.38
Temperature coefficient (%/
؇
C)
1mol/l 1/10mol/l 1/1000mol/l
• Finding Temperature Coefficient
If temperature coefficient tables containing the liquid to be measured can not be found,
measure conductivity twice at two liquid temperatures between 10 and 30
؇C with
temperature coefficient set to 0.00 and use the equation shown below to find approximate
temperature coefficient (
␣).