Titra
Lab
®
TitraLab 870 Reference Manual
Page 273
7. Conductivity measurements
To determine a conductivity value, the TIM870 performs the following operations in this order:
1.
Measurement of the G
S
conductance (value displayed live).
2.
Cable correction (cable resistance and cable capacity correction): G
m
corrected
conductance value.
3.
The cell constant is used to calculate the
κ
conductivity at the T sample temperaure
(measured or entered).
4.
Temperature correction: conductivity recalculated at the T
ref
reference temperature or at
25°C depending on the method programmation.
7.1 Cable correction
The cable correction takes into account the cable resistance and the cable capacitance.
1. Cable resistance
The influence of the cable resistance on the G
m
measured conductance is as follows:
Where:
•
G
s
= conductance of solution (S)
•
R= cable resistance (
Ω
)
The cable resistance is entered upon creating a 2 or 3 pole conductivity cell. Enter a cable
resistance of 0 for a 4-pole conductivity cell. This value cannot be changed afterwards.
Refer to "Create electrode", page 87.
2. Cable capacity
The cable capacity influences the measurements of very low conductance. The TIM870
performs a cable capacity correction when low conductance are measured (< 4 µS).
The equation used by the TIM870 enables an accurate measurement correction to be
obtained for cable capacities up to 1000 pF.
The cable capacity is entered upon creating the electrode. This value cannot be changed
afterwards.
Refer to "Create electrode", page 87.
(
)
S
S
m
G
R
G
G
×
+
=
1
Summary of Contents for TitraLab 870
Page 1: ...TitraLab 870 pH EP IP EC ISE Titration Workstation Reference Manual D21T060...
Page 2: ...D21T060 Printed by Radiometer Analytical SAS 2008 02F...
Page 22: ...TitraLab TitraLab 870 Reference Manual Page 22...
Page 23: ...Practical examples s...
Page 24: ......
Page 32: ...TitraLab TitraLab 870 Reference Manual Page 32...
Page 40: ...TitraLab TitraLab 870 Reference Manual Page 40...
Page 41: ...Glossary...
Page 42: ......
Page 255: ...Appendixes...
Page 256: ......
Page 258: ...TitraLab TitraLab 870 Reference Manual Page 258...
Page 262: ...TitraLab TitraLab 870 Reference Manual Page 262...
Page 280: ...TitraLab TitraLab 870 Reference Manual Page 280...
Page 286: ...TitraLab TitraLab 870 Reference Manual Page 286...