76 . Spectrum 100 Series User’s Guide
Purging the Spectrometer
Under most circumstances, you do not need to purge the optical system. However, after
performing any maintenance tasks that involved opening the main cover, you may purge
the optical system to remove water vapor and CO
2
that entered while the system was
open.
Purge the sample compartment if you need to make sure that no residual water vapor or
CO
2
peaks are visible in the spectrum.
There are two separate sets of connectors for purge gas lines, one for the sample
compartment and one for the optical system. You can purge with either dry air or
nitrogen. Both remove water vapor; however, nitrogen is preferable because it also
removes atmospheric carbon dioxide.
A typical cylinder of dry nitrogen (or dry air) stores 220 ft
3
at 2200 lbf/in
2
(6.26 m
3
at 1.4
x 104 kPa). Make sure that the gas is free of oil, water, or dirt particles larger than 25 µm
(0.001 inch).
WARNING
Do not use a flammable gas to purge the instrument. The
spectrometer contains a hot source, and a fire or explosion will result.
Only use clean, dry, oil–free nitrogen or air to purge the instrument.
WARNING
Never connect the purge tubing directly to a gas cylinder or other high
pressure supply; always use a pressure regulator and set the pressure
to a maximum of 1 lbf/in
2
(6.9 kPa) before you start the flow.
A length of clear plastic tubing (4 mm internal diameter) will be required to transfer the
gas from the gas bottle to the instrument purge connectors.
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