Metrohm 820 IC Separation Center - Manual (Page 60)

3 Operation
819 IC Detector / 820 IC Separation Center
52
Zero Triggers the auto-zero function.
Zero Switch off the auto-zero function.
"Auto-zero" is the name used for the automatic electronic back-
ground compensation, i.e. the current measured Conductivity value
is set to zero and hence lies in the middle of the selected full-scale
range.
The auto-zero function is disabled, if the actual value of the absolute
conductivity abs. Cond. out of the limit set by the measuring Range
(see Fig. 27), the diagram below shows the operating principle of the
auto-zero function.
Fig. 26: Operating principle of Auto-zero
Before the auto-zero function is activated for the first time or after it
has been switched off, the measuring signal lies outside the full-
scale range; it is automatically set to 0 µ S/cm each time the Zero
key is pressed.
The auto-zero function can be triggered at any time using the Zero
key.
The auto-zero function works properly only when the measured
value remains relatively stable (e.g. not during the appearance of
the injection peak at the start of the chromatogram).
Zeit
0
+ Full Scale
– Full Scale
+ 1.8 Full Scale
– 1.8 Full Scale
Conductivity
Conductivity
Out of range Conductivity
Out of range Conductivity
Out of range
Zero Zero Zero