Xylem MULTI 1970I PORTABLE MULTIPARAMETER METERS - Manual (Page 29)

Multi 1970i Operation
27
4.4 Dissolved oxygen
4.4.1 General information
Note
D. O. measurements with the Multi 1970i can only be carried out using
a CellOx 325 or StirrOx G D. O. sensor. The stirrer of the StirrOx G
D. O. sensor has to be supplied with voltage separately using the
NT/pH Mix 540 power supply.
You can measure the following variables:
z D. O. concentration
z Oxygen saturation
The measuring instrument is supplied with the following functions:
z AutoRange (automatic switchover of the measurement range). If a
measuring range is exceeded, AutoRange causes the measuring in-
strument to change automatically to the next higher measuring
range and back again. Therefore, the instrument always measures
in the measuring range with the highest possible resolution.
z The AutoRead function (drift control) for checking the stability of the
measurement signal. This ensures the reproducibility of the measur-
ing signal. For details of how to switch the AutoRead function on/off,
see page 31.
Warning
When connecting an earthed PC/printer, measurements cannot be per-
formed in earthed media as incorrect values would result.
The RS232 interface is not galvanically isolated.
Preparatory activities Perform the following preparatory activities when you want to measure:
1 Connect the D. O. sensor to the measuring instrument. If the D.
O. sensor is connected to the active REL socket, press the
<M> repeatedly if necessary until the O
2
status display indica-
tor appears. If the D. O. sensor is connected to the inactive
REL socket, press the <M> key for 2 s, until the O
2
status dis-
play indicator appears.
2 Calibrate or check the measuring instrument with the sensor.
How to calibrate is described in section 4.4.5 from page 21.
3 Use <
▲> <▼> to toggle between the measuring modes, D. O.
concentration (mg/L) and D. O. saturation (%).