13 Detector
13.3 Thermal conductivity detector (TCD)
165
GC-2010 Plus
13.3.3 Setting the detector gas flows
The gas tubing is routed so that the reference gas effluent is used as the makeup gas of the
TCD. Helium and nitrogen are available as the makeup gas.
The TCD sensitivity is proportional to the difference in thermal conductivity between the
sample and the carrier gas. Because the thermal conductivity of the sample is lower than
that of the carrier gas, the TCD sensitivity increases as the thermal conductivity of the carrier
gas increases.
For high sensitivity analysis, use gas with a purity of 99.9995 % or more.
Thermal conductivity k (x10
-4
Wm
-1
K
-1
) at room temperature, 300 K
13.3.3.1 Screen description
Select [Det Gas] (PF menu) from the [DET] key main screen to display the flow screen
shown in Fig. 13.3.4
When the start sequence is the “Start Flow” status on the [SYSTEM] key screen, the
makeup gas flow starts. When the stop time elapses and the detector temperature
drops to the value set by [Stop Seq] (PF menu) on the [Det Gas] (PF menu), the
makeup gas flow stops.
Gas
Thermal
conductivity
Gas
Thermal
conductivity
Simple
compounds
He 1499
Inorganic
compounds
CO
2 166.2
H
2 1815 H2O 181
N
2 259.8
Organic
compounds
acetone 115
Ar 177.2 hexane 128
Fig. 13.3.4 Setting the detector gas flows
Refer to “OPTIMAL FLOW”
in “13.3.3.2 Parameter list”,
and check whether the flow
rate of each detector gas is set
correctly. If not, set it to the
correct value.
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