Teledyne T200, Руководство по эксплуатации, Страница: 295 / 425

Teledyne API
– T200 NO/NO
2
/NO
X
Analyzer Operation Manual Principles of Operation
293
Table 13-2: T200 Valve Cycle Phases
Phase
NO/ NO
X
Valve
Status
Auto Zero
Valve
Status
Time
Index
Activity Figure
NO
Measure
Open to
Auto Zero
valve
Open to
reaction cell
0 - 2 s
Wait period (NO dwell time). Ensures reaction cell has
been flushed of previous gas.
Figure
13-3
2 - 4 s Analyzer measures chemiluminescence in reaction cell.
NO
X
Measure
Open to
NO
2
converter
Open to
reaction cell
4 – 6 s
Wait period (NO
X
dwell time). Ensures reaction cell has
been flushed of previous gas.
Figure
13-3
6 – 8 s
Analyzer measures NO + O
3
chemiluminescence in
reaction cell.
Cycle repeats every ~8 seconds
Auto
Zero
Open to
Auto Zero
valve
Open to
vacuum
manifold
0 – 4 s
Wait period (AZERO dwell time). Ensures reaction cell
has been flushed of sample gas and chemi-
luminescence reaction is stopped.
Figure
13-4
4 - 6 s
Analyzer measures background noise without sample
gas
Cycle repeats every minute
13.2.2. FLOW RATE CONTROL - CRITICAL FLOW ORIFICES
Sample gas flow in the T200 analyzer is created via the use of several flow control
assemblies (see Figure 13-6 for an example) located in various places in the gas streams
of the instrument. These assemblies consist of:

a critical flow orifice

two o-rings, Located just before and after the critical flow orifice, the o-rings seal the
gap between the walls of assembly housing and the critical flow orifice

a sintered filter

a spring (applies mechanical force needed to form the seal between the o-rings, the
critical flow orifice and the assembly housing)
Figure 13-6: Flow Control Assembly & Critical Flow Orifice
06858E DCN7057