Teledyne 6400EH - Sulfur Dioxide Analyzer - Manual (Page 57)

UV Fluorescence SO2 Analyzer Troubleshooting
Teledyne Analytical Instruments 45
7. if you are replacing the Critical Flow Orifice itself
(p/n:00094100), make sure that the side with the colored window
(usually RED) is facing upstream to the flow gas flow.
8. Re-assemble in reverse order. See the Spares List in Appendix B
for part numbers.
9. After re-connecting the power and pneumatic lines, flow check
the instrument as described in the Section 11.5.2 of the 6400E
Operator’s Manual.
Figure 10-1: Flow Control Assembly