Dissolved oxygen
Multi 3620 IDS
50
ba77169d06
10/2021
Criteria for a stable
measured value
The
Stability control
function checks whether the measured values are stable
within the monitored time interval.
The minimum duration until a measured value is assessed as stable is the mon-
itored time interval. The actual duration is mostly longer.
7.1.2 Measuring the temperature
For reproducible D.O. measurements, it is essential to measure the tempera-
ture of the test sample.
IDS D.O. sensors measure the temperature with a temperature sensor inte-
grated in the IDS sensor.
7.2
FDO
®
check procedure (check of the FDO
®
925)
7.2.1 Why should you check the sensor?
With the FDO
®
Check procedure, you can find out in a simple manner whether
the
FDO
®
925
®
D.O. sensor should be cleaned or calibrated.
7.2.2 When should you check the sensor?
Checking can be useful in the following cases:
When the check interval has expired
If the measured values seem to be implausible
If you assume that the sensor cap is contaminated or at the end of
its lifetime
After the sensor cap was exchanged
Routinely within the framework of the company quality assurance
7.2.3 Carrying out the FDO
®
check procedure
FDO
®
check proce-
dure
Check in water vapor-saturated air.
Use the check and storage beaker (FDO
®
Check) to carry out the
FDO
®
Check
®
procedure.
Measured
parameter
Time interval
Stability in the time inter-
val
D.O. concentra-
tion
20 seconds
Δ
: better than 0.03 mg/l
D.O. saturation
20 seconds
Δ
: better than 0.4 %
D.O. partial
pressure
20 seconds
Δ
: Better than 0.8 mbar
Temperature
15 seconds
Δ
: better than 0.5 °C
