Radiometer Analytical TitraLab 870, Справочное руководство

Страница: 274 / 286

Titra Lab ® TitraLab 870 Reference Manual
Page 274
7.2 Cell constant correction
The TIM870 calculates and displays the
κ
conductivity of a solution on the basis of the
G
m
conductance measured (after cable resistance and capacity correction) and the K cell
constant of the conductivity cell used.
κ
(in S
.
cm
-1
) = K x G
m
(in S)
The K constant (expressed in cm
-1
) is a specification of the conductivity cell which depends on
the cell geometry.
To measure conductivities, you must know K. With the TIM870, you can directly enter the K
value in the Edit electrode menu (
see "Cell constant (parameter)", page 74. ) or determine K
by calibrating the conductivity cell ( see "Electrode calibration (conductivity)", page 108. ).
7.3 Temperature correction
Two types of temperature correction are available using the TIM870:
• The linear correction,
• The non-linear correction of "Natural water" type.
The linear correction
Conductivities are corrected to a reference temperature using a temperature coefficient (
θ
), a
reference temperature and the following equation:
Where:
• T
ref
= reference temperature in °C
• T= sample temperature in °C
•
κ
Tref
= conductivity at T
ref
•
κ
T
= conductivity at T
•
θ
= temperature coefficient of the sample in %/°C
With the TIM870, the reference temperature can be entered between 0 and 99°C (resolution:
1°C) and the temperature coefficient between 0.00 and 9.99 %/°C (resolution: 0.01 %/°C).
These 2 parameters are available in the Edit method > Parameters menu,
see "Temp. correction None/Linear/Nat. water", page 246.
( )
T
ref
Tref
T T
κ
θ
κ ×
− × +
=
100
100