Measuring The Temperature; Fdo ® Check Procedure; Why Should You Check The Sensor; When Should You Check The Sensor - wtw Oxi 3315 Operating Manual

Dissolved oxygen
Criteria for a stable
measured value
®
check proce-
FDO
dure
26
The Stability control function checks whether the measured values are stable
within the monitored time interval.
Measured parameter
D.O. concentration
Oxygen saturation
D.O. partial pressure
Temperature
The minimum duration until a measured value is assessed as stable is the mon-
itored time interval. The actual duration is mostly longer.

5.1.2 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.
®
5.2 FDO check procedure

5.2.1 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.

5.2.2 When should you check the sensor?

Checking can be useful in the following cases:
 When the check interval has expired
(the [check] status indicator is displayed.)
 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

5.2.3 Carrying out the FDO

Check in water vapor-saturated air.
Use the check and storage beaker (FDO ® Check) to carry out the FDO ®
check procedure.
Time interval Stability in the time
interval
20 seconds Δ : better than 0.03 mg/l
20 seconds Δ : better than 0.4 %
20 seconds Δ : Better than 0.8 mbar
20 seconds Δ T (°C): Better than 0.02
®
check procedure
Oxi 3315
ba75944e02 03/2012