INFICON 3000 Micro GC Gas Analyzer Operating Manual - Manual (Page 42)

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3000 Micro GC Operating Manual
3.3.5 Detector
3000 Micro GC uses a MEMS based TCD, which has a 240 nL internal cell volume.
(See
Figure 3-12 .) The small volume provides for excellent sensitivity. For some
components, a detection limit of 1 ppm can be achieved.
NOTE: TCD sensitivity is matrix, carrier gas, and component dependent.
The TCD uses a Wheatstone bridge design and has a sample and reference
channel. The TCD detects the difference in thermal conductivity of the gas traveling
through the reference side (pure carrier gas) versus the gas traveling through the
sample side (carrier gas plus the sample gas). When ON, the TCD filament is hot.
3000 Micro GC monitors the column pressure. If carrier gas flow is turned off, the
TCD will automatically turn off.
Figure 3-12 MEMS TCD detector
3.3.6 D-Board
A Detector board, also known as a D-board, is attached to the side of each module.
The D-Board controls the module conditions and communicates module
information and setpoints to the Communications Board (C-Board, see
section
3.4.2 on page 3-15 ). 3000 Micro GC supports two types of D-board: Enhanced and
Standard.
3.3.6.1 Enhanced D-Board
Enhanced D-Board circuitry significantly reduces solvent peak tailing, resulting in
better chromatography and improved sensitivity of peaks eluting after the solvent
peak (e.g., air). This feature is most useful for applications that involve low ppm
trace analysis in a solvent gas.
3.3.6.2 Standard D-Board
The Standard D-Board circuitry is for general purpose applications with a
mid-to-high ppm analysis requirement.