Xylem YSI VARiON Plus 700 IQ H, Operating Manual, Page: 29 / 62

VARiON
® Plus
700 IQ H Matrix adjustment, check and calibration
29
ba76207e02 12/2020
4 Matrix adjustment, check and
calibration
4.1 General information
Calibration free
operation
The VARiON
® Plus
700 IQ H sensor is immediately ready to measure
after being equipped with electrodes. For precise measurements, it is
only necessary to adjust the electrodes to the sample matrix ("matrix
adjustment"). In the recommended application (see section
1.3 R
ECOMMENDED FIELDS OF APPLICATION
), the measuring characteris-
tics of the electrodes remain stable for their entire service life. Thus,
calibration is not recommended.
Possible changes of the sample matrix can be determined by occa-
sional comparison measurements (e.g. photometer) and compensated
for by a new matrix adjustment as necessary. The sensor does not
have to be taken out of the sample for this. At the same time, a matrix
adjustment provides information on the state of the electrodes.
Drift potential: Simultaneously with the matrix adjustment (or calibration), the drift volt-
age DV(mV) of the electrode is determined. It serves to evaluate the
long-term behavior of the electrode. The drift voltage changes due to
the following factors:
 Influences due to the sample composition (matrix)
 Changes of the electrode characteristic(s).
Zeroing The temporal change of the drift voltage is recorded in the calibration
history so the long-term behavior of a electrode can be evaluated. As a
start value, the user has to set the drift voltage to zero (zeroing) at the
beginning of this evaluation period in order to observe any changes in
the calibration history.
The zeroing for an electrode is done within the MATRIX ADJUSTMENT
or CALIBRATION procedure if the zeroing was selected for the elec-
trode (checked off). It becomes effective if the procedure was success-
fully carried out.
Carry out the zeroing when commissioning the electrode so you can
watch in the calibration history the entire working period of the elec-
trode.
It is not possible to zero an electrode with the CHECK procedure, as
this procedure stores no data in the sensor.
Resetting the slope with
the zeroing
Zeroing with the MATRIX ADJUSTMENT procedure resets the slope to
the default setting (+ or - 59.2 mV) at the same time. Zeroing with the
CALIBRATION procedure replaces the existing slope with the newly
determined value.