Thermo Scientific 450iQ Instruction Manual page 281

Optional Equipment
Internal Permeation Span Source
Figure 9–12. Installing Glass Tube pt 3
7. Insert thermistor assembly into oven tube. Make sure it bottoms out.
8. Tighten thumb screw to expand o-ring for complete seal.
9. Fasten nut.
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Thermo Scientific 450iQ Instruction Manual