Campbell Scientific TGA100 Trace Gas Analyzer Manual - Manual (Page 73)

that site’s gradient valve assembly to a corresponding inlet on the site selection assembly located near the TGA100. The
site selection assembly consists of four nonlatching three-way valves, one for each site. The outlets of the four valves
are connected to a manifold that is connected to the TGA100 sample inlet. The TGA100 controls the site selection
system using timing parameters supplied by the user. Normally each site is measured for 15 to 60 minutes before
switching to the next site.
Purge Dryer
Sample Dryer
Site Selection Control Cable
Sample
Bypass
Dryer Purge
Sample
Gradient
Intake
Filter
Needle Valve
Gradient Valve
Site 2
Site 3
Site 4
Site 1
Assemblies
Valve
Assembly
Control Cable
Sample Tubing
Gradient Valve
Control Cables
From Each Site
To Each Site
Site Selection
Sampling
System
Figure 5-5. Gradient Measurement at Four Sites
To configure the TGA100 for this example site selection assembly:
1) Connect digital output bit 2 to site valve 1, bit 3 to site valve 2, bit 4 to site valve 3, and bit 5 to site valve 4.
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