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Instrument Overview
Carrier Gas Connection
Carrier Gas Connection
The carrier gas line is connected to the Micro GC at the back panel Carrier 1 or Carrier 2 port.
Do not use any kind of plastic tubing since air will diffuse through the tubing, which may cause
C AU T I O N
noisy baselines and decreased sensitivity. The metal tubing must be clean for GC use. Buy either
flamed or chromatographically clean tubing.
Specifications for the carrier gas:
Pressure:
Purity:
Dry and free of particles:
Gas Clean filters are recommended to remove any traces of moisture and oxygen. For low-level
analysis, consider using a better grade of carrier gas.
Gas Clean filters are filled with nitrogen. If you are not using nitrogen as the carrier gas, flush filters
and gas lines after installation of a new filter.
The type of analysis you want to perform dictates the type of carrier gas to use. The difference
between the relative thermal conductivity of the carrier gas and the sample components should
be as high as possible. See
Table 3
Gas type
Hydrogen
Helium
Methane
Oxygen
Nitrogen
Carbon monoxide
Your Micro GC is configured for a specific carrier gas, either He and H
WAR N IN G
any carrier gas selection in your Agilent data system corresponds to the carrier gas physically
connected to your Micro GC. Use only the carrier gas corresponding to this configuration. If you
change the carrier gas type plumbed to the Micro GC, you must change the corresponding
carrier gas type in the data system.
Hydrogen is flammable. If you are using hydrogen as a carrier gas, pay particular attention to
WAR N IN G
possible leaks at connections inside and outside of the Micro GC. Use an electronic leak tester.
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Table 3
Relative thermal conductivities
Relative thermal
conductivities
47.1
37.6
8.9
6.8
6.6
6.4
550 kPa ±10 kPa (80 psi ±1.5 psi)
99.999 % minimum
Gas Clean filters recommended
for several relative thermal conductivities.
Gas type
Ethane
Propane
Argon
Carbon dioxide
Butane
Relative thermal
conductivities
5.8
4.8
4.6
4.4
4.3
or N
and Ar. Ensure that
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Agilent 990 Micro GC User Manual
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