Xylem Oxi 1970i PORTABLE DISSOLVED OXYGEN METERS - Manual (Page 21)

Oxi 1970i Operation
21 ba75691e01 01/2007
4.3 Calibration
Why calibrate? D. O. sensors age. This changes the slope of the D. O. sensor. Calibra-
tion determines the current slope of the sensor and stores this value in
the instrument.
Thus, you should calibrate at regular intervals.
Calibration data records The Oxi 1970i administrates two sets of calibration data:
Sensors of different classes can be calibrated separately. When a sen-
sor of one class is calibrated the calibration data of the other class re-
main stored. The Oxi 1970i recognizes the class of the connected
sensor and automatically uses the correct calibration data.
Calibration procedures The Oxi 1970i provides 2 calibration procedures:
z Calibration in water vapor-saturated air.
To calibrate the CellOx 325, use theOxiCal
®
-SL air calibration ves-
sel (accessory), to calibrate the DurOx 325, use the OxiCal
®
-D air
calibration vessel (contained in the scope of delivery of the sensor).
z Calibration via a comparison measurement (e. g. Winkler titration
according to DIN EN 25813 or ISO 5813). At the same time, the rel-
ative slope is adapted to the comparison measurement by a correc-
tion factor.
When to calibrate? z After connecting another D. O. sensor
z If the sensor symbol flashes, i. e. after the calibration interval has ex-
pired
Calibration interval The calibration interval (Int 3) is set to 14 days in the factory. You can
select the interval in the range of 1 ... 999 days.
AutoRead The calibration procedure automatically activates the AutoRead func-
tion.
Displaying calibration
data
Each time the instrument is switched on, the calibration data are shown
on the display for a short time (see section 4.1 S
WITCHING ON THE MEA -
SURING INSTRUMENT ). In order to view the calibration data, switch the
measuring instrument off and switch it on again.
z Set 1, for sensor class 1: – Oxygen depth armature
– CellOx 325, or
– StirrOx G
z Set 2, for sensor class 2: – DurOx 325