Delta-T HH2, User Manual

Page: 52 / 124

WET Sensor

45
Compensation
Readings of electrical conductivity can be temperature compensated if required.
For some applications it is useful to know the true electrical conductivity at the
measurement temperature. In that case uncompensated readings are required, and
this is the default for the HH2.
For most applications the electrical conductivity is a means of estimating the ionic
content of the pore water, and for these applications it is necessary to compare
readings after they have been adjusted to a standard temperature.
Unfortunately this isn’t straightforward because:
• 20°C and 25°C are both used as standards,
•
The temperature compensation percentage depends on the particular mixture of
ions present in the pore water. For example:
ion temperature sensitivity of EC*
Na
+
2.1
K
+
1.9
½ Ca
++
2.1
H
+
1.5
NH
4
+
1.9
Cl
 1.9
NO
3

1.8
OH 
1.5
P
2
O
5
 not known
* The values quoted are approximate for 25°C.
The choice of standard temperature and compensation % will depend on what is
commonly used for comparison purposes within your application.
Temperature
Options: None, 25 ° C, 20 ° C Default: None.
Select
Options, Compensation, Temperature
.
Scroll and press Set to select one.
Press Esc to return to the main menu.
Percent
Options: -1.0 to 4.0% Default: 2.0%
Select
Options, Compensation, Percent
.
Scroll and press Set to select one.
Press Esc to return to the main menu.