Optional Equipment
Filter Wheel Purge
9-2 Model 48i Instruction Manual Thermo Electron Corporation
Figure 9-1. Purge Housing Assembly
Calibration Note The stability of the purge gas is very important. Since this gas is in the same
optical path as the sample, changes in the composition of the purge gas can
change the calibration of the instrument. Therefore, either zero air or a
non-toxic dry inert gas, such as nitrogen, is recommended for use in this
option. Other than the effect of the purge gas, operation and calibration of
the instrument is not affected by the addition of the purge housing.
A constant purge flow of approximately 140cc/min is recommended for
optimum performance. This is produced by feeding a purge gas to the rear
panel bulkhead at a constant pressure of 15 psig. A 0.000-inch glass
capillary (green) will deliver the required 140cc/min purge flow. Flows
greater than this are not recommended due to unstable cooling effects on
the IR source. Lower flows are acceptable as long as the purge housing is
adequately purged for the application.
Purge Wheel Housing
Motor Plate
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