330 Thermal Conductivity Detector (TCD)
Theory of operation
2 of 24
Jun 2001
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Figure 330-2 TCD flow path switching
Vent
Reference
switching
Makeup
valve
Column effluent diverted to bypass
channel. Filament surrounded by
reference gas.
Column effluent diverted to filament
channel. If sample is present, thermal
conductivity rises or falls, depending on
gas type.
flow