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8.2.2
Water Flushed with Nitrogen Gas
Fill water into a glass flask (e.g. Duran flask) with a lid prepared
with holes for inserting the oxygen sensor and a temperature
sensor. Close it and stream for about 10 minutes nitrogen gas
through the water. You might speed up this process by first boiling
the water (and thereby removing all dissolved gases) and then
stream the nitrogen gas during cooling through it. Insert the
oxygen sensor, and optionally also the temperature sensor, into
the flask, let it equilibrate and perform the calibration as described
in chapter 7.
Please consider that streaming N2 gas through water may cause
cooling of the water
.
Ensure a
correct temperature determination
of the 0% calibration standard!
8.2.3
Nitrogen Gas
Flush 100% nitrogen gas through a glass flask (e.g. Duran flask)
with a lid prepared with holes for inserting the oxygen sensor and a
temperature sensor. Ensure that all air has been replaced by the
nitrogen gas before performing the calibration. Insert the oxygen
sensor, and optionally also the temperature sensor, into the flask,
let it equilibrate and perform the calibration as described in
chapter 7.
Ensure that no ambient air enters the flask again during the
calibration process. Convectional gas transport is a very fast
process! It is therefore advised to keep flushing the flask with
nitrogen gas during the complete calibration process!
Please consider that nitrogen gas from gas bottles might be
significantly
cooled down
by the decompression process. Ensure a
correct temperature determination
of the calibration standard!
