Teledyne Sample Gas Flow Valves and Routing, 9110T Valve Cycle Phases, NO/ no

Model 9110T NOx Analyzer Principles of Operation

Figure 13-7. Vacuum Manifold, Standard Configuration

Configurations will vary depending on the optional equipment that is installed. For example:

∙An 9110T with the optional internal span gas generator installed will add another FT8 connector and orifice assembly to the manifold where the FT28 fitting is shown in the above drawing.

∙An optional sample gas dryer will add a Tee-fitting so that two ¼” tubes can be connected to the same port.

13.2.1.2. Sample Gas Flow Valves and Routing

As discussed in Section 13.1, the measurement of NOx, NO and NO2 requires that the sample gas flow cycles through different routes that include and exclude various scrubbers and converters. There are several valves that perform this function:

∙The NO/NOX valve directs the sample gas either directly to the reaction cell or through the unit’s NO2 converter, alternating every ~8 sec.

∙The Auto Zero valve directs the sample gas stream to completely bypass the reaction cell for dark noise measurement once every minute, which is then subtracted as a measurement offset from the raw concentration signal.

Table 13-2: 9110T Valve Cycle Phases

	NO/ NOX	Auto Zero	Time
Phase	Valve	Valve		Activity	Figure
			Index
	Status	Status
NO	Open to	Open to	0 - 2 s	Wait period (NO dwell time). Ensures reaction cell has	Figure
	Auto Zero			been flushed of previous gas.
Measure	valve	reaction cell			13-3
			2 - 4 s	Analyzer measures chemiluminescence in reaction cell.
	Open to		4 – 6 s	Wait period (NOX dwell time). Ensures reaction cell has
NOX		Open to		been flushed of previous gas.	Figure
Measure	NO2	reaction cell			13-3
				Analyzer measures NO + O3 chemiluminescence in
	converter		6 – 8 s
				reaction cell.
			Cycle repeats every ~8 seconds

Teledyne Analytical Instruments 329