Metrohm NIRS Analyzer PRO - Manual (Page 35)

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This photo shows a typical accumulation of
sample on the face of the spoon probe. This
photo was taken in a fluid bed dryer, in
between purge cycles.
As sample accumulates, the instrument will take
a sample scan and produce sample spectra for
analysis. The scan timing must sometimes be
adjusted to the flow rate, to assure that enough
sample has accumulated.
When the purge air system is activated, the
pressure through the purge holes “blasts” the
sample from the face of the probe. While a
slight film may be left on the probe window,
this is not enough to skew spectra, and can be
ignored.
The photo shows the internal control for the air
purge. This valve is controlled by Vision. A setup
screen allows setting of intervals and timing.
This shows a typical setup, though yours will
vary.
IMPORTANT NOTE:
The purge gas provided to the probe must be instrument grade, to avoid coating the probe window
with foreign substances.
Specifically, if air is provided, it should be from an “oil-less” source, and should be clean, dry, and
filtered. “Instrument-grade” air, or pure nitrogen, are two possible types of purge gas that may be
used.
The user is responsible for chemical compatibility with
the process, cleanliness of the purge gas, temperature
variation, pressure, and control over flow.