Backflush Option - Agilent Technologies 490 User Manual

Backflush Option

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8
Natural gas analysis, straight
Figure 19 Natural gas analysis
490 Micro GC User Manual
Backflush to vent is an advanced technique used to prevent
later-eluting compounds from reaching the analytical column
and detector. The main reason for applying this technique is to
keep the analytical column clean and reduce analysis time.
The Micro GC is optionally available with GC modules that
incorporate backflush capabilities.
1 = Methane
2 = Ethane
3 = Propane
4 = iso-Butane
5 = Butane
6 = iso-Pentane
7 = Pentane
6
7
50 s
A backflush system always consists of a pre-column and an
analytical column. The two columns are coupled at a pressure
point, which makes it possible to invert the carrier gas flow
direction through the pre-column at a preset time, called the
backflush time. See
The injector, two columns, and detector are in series.
The sample is injected onto the pre-column where a
pre-separation takes place; injection takes place in normal
mode. See Figure 20
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3
5
4
8
Natural gas analysis, with backflush at 8 seconds
Figure 21 on page 58.
on page 58.
4
GC Channels
50 s
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