Replacing Critical Flow Orifices - Teledyne T200 Operation Manual

Teledyne API – T200 NO/NO

11.3.10. REPLACING CRITICAL FLOW ORIFICES

06858E DCN7057
/NO Analyzer Operation Manual
2 X
There are several critical flow orifices installed in the T200 (see Figure 13-7 for a
pneumatic location of each orifice). Despite the fact that these flow restrictors are
protected by sintered stainless steel filters, they can, on occasion, clog up, particularly if
the instrument is operated without sample filter or in an environment with very fine,
sub-micron particle-size dust.
Figure 11-7: Critical Flow Orifice Assembly
To clean or replace a critical flow orifice:
1. Turn off power to the instrument and vacuum pump.
2. Remove the analyzer cover and locate the reaction cell (Figure 11-5 and Figure
11-6).
3. Unscrew the 1/8" sample and ozone air tubes from the reaction cell.
4. For orifices on the reaction cell (Figure 11-6): Unscrew the orifice holder with a
9/16" wrench.

This part holds all components of the critical flow assembly as shown in Figure
11-7.

Appendix B contains a list of spare part numbers.
5. For orifices in the vacuum manifold: the assembly is similar to the one shown in
Figure 11-7, except:

Without the orifice holder, P/N 04090, and bottom O-ring, P/N OR34 and;

With an NPT fitting in place of the FT 10 fitting.
6. After taking off the connecting tube, unscrew the NPT fitting.
Instrument Maintenance
223