Routine Maintenance . 65
Cooling the MCT Detector (If Fitted)
Optionally, the Frontier FT-IR may be fitted with an MCT (mercury cadmium telluride)
detector. When it is fitted in the instrument it must be cooled to 77 K before you collect
spectra. The detector is mounted in a dewar that can be filled with liquid nitrogen. The
detector is not enabled until it has been sufficiently cooled.
WARNING
Do not site the instrument in a poorly ventilated area if liquid nitrogen
will be used to cool a detector.
Oxygen depletion in an enclosed space does not trigger a gasping reflex,
and errors of judgment, confusion, or unconsciousness can occur in
seconds and without warning.
WARNING
Be sure to wait the specified time when filling the funnel and before
replacing the plug. This enables the bubbling nitrogen to settle down and
the pressure to dissipate. In addition to wearing safety goggles at all
times, stand back from the instrument after each time you fill the funnel.
WARNING
The extremely low temperature of liquid nitrogen can burn skin and
eyes. Avoid exposure by wearing protective gloves and safety goggles
whenever you work with it.
WARNING
As liquid nitrogen cools the detector it evaporates so rapidly that the
resulting pressures can send a funnel or detector cap suddenly and
forcefully shooting upward from the top of the dewar.
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