Agilent Technologies 6890 Series Service Manual page 269

330 Thermal Conductivity Detector (TCD)
Theory of operation
switching valve that switches paths through the TCD cell several times a
second. The switching valve oscillates between two flowpaths, one for each
channel of the TCD cell. The makeup gas line sweeps past the end of the
column and carries the column effluent into the TCD cell.
Reference gas
Makeup gas
Figure 330-5
6 of 24
Pressure
On/off
regulators
solenoid
valves Restrictors
Manual TCD flow diagram
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Reference
switching
valve
Makeup flow
Vent
Jun 2001