wtw Multi 350i, Operating Manual

Page: 51 / 108

Multi 350i Operation
49
4.6 Dissolved oxygen
4.6.1 General information
You can measure the following variables:
!
DO concentration
!
DO saturation index ("DO saturation")
!
DO partial pressure
DO measurements with the Multi 350i can be carried out using a Con-
Ox, CellOx 325, DurOx 325 or StirrOx G DO sensor. The stirrer of the
StirrOx G DO sensor has to be supplied with voltage separately using
the NT/pH Mix 540 power supply. The measuring instrument automat-
ically recognizes the type of the connected DO sensor.
The measuring instrument is supplied with the following functions:
!
AutoRange (automatic switchover of the measurement range), If a
measuring range is exceeded, AutoRange causes the measuring in-
strument to automatically change to the next higher measuring
range and back again. Therefore, the instrument always measures
in the measuring range with the highest possible resolution.
!
The AutoRead function (drift control) for checking the stability of the
measurement signal. This ensures the reproducibility of the measur-
ing signal. The display of the measured variable flashes until a sta-
ble measured value is available.
Note
Incorrect calibration of DO sensors will result in incorrect measured
values.
Calibrate at regular intervals.
Caution
When connecting an earthed PC/printer, measurements cannot be
performed in earthed media as incorrect values would result.
The RS232 interface is not galvanically isolated.
Temperature sensor The DO sensor has an integrated temperature sensor that always mea-
sures the current temperature of the test sample.