Agilent Technologies 490 Micro GC User Manual

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Agilent 490 Micro GC Natural Gas Analyzer
User Manual
Agilent Technologies
3
Tuning the Backflush Time
Tuning the Backflush Time on CP-Molsieve 5A, PoraPLOT U, or CP-Sil 5 CB
Tuning the backflush time is necessary for each new
CP-Molsieve 5A channel, PoraPLOT U channel, and 4 meter
CP-Sil 5 CB channel. This chapter describes how to tune the
backflush time for these channels.
• The goal for tuning the CP-Molsieve 5A is to get all methane
on the column while later-eluting components such as
moisture, carbon dioxide, ethane, and higher hydrocarbons
are backflushed.
• The PoraPLOT U is tuned on the propane peak while all other
components that elute after propane are backflushed.
• The 4 meter CP-Sil 5 CB is tuned on the n-pentane while all
other hydrocarbons that elutes after n-pentane are
backflushed.
Tuning procedure for the backflush time
1 Set the backflush time to 0 seconds and analyze the
checkout sample or a proper sample for the specific channel.
The goal of this is to identify the components in the
calibration standard.
2 Change the backflush time to 10 seconds and perform a run.
The following can be observed:
• When the backflush time is set too early, the peaks of
interest are partially or totally backflushed.
• If the backflush time is set too late, the unwanted
components are not backflushed and show up in the
chromatogram.
3 Perform runs with different backflush times until there is no
huge difference in the peak of interest. To fine tune the
backflush time, set smaller steps (for example 0.10 seconds)
until you find the optimal backflush time.

Agilent Technologies 490 Micro GC Specifications

General

Brand	Agilent Technologies
Model	490 Micro GC
Category	Measuring Instruments
Language	English