User guide

Configuration 2
Advanced User Guide 35
You should check configurations for all columns to verify that
they specify the correct pressure control device at each end. The
GC uses this information to determine the flow path of the
carrier gas. Only configure columns that are in current use in
your GC’s carrier gas flow path. Unused columns configured
with the same pressure control device as a column in the
current flow path cause incorrect flow results.
It is possible, and sometimes appropriate, to configure both
installed columns to the same inlet.
When splitters or unions exist in the carrier gas flow path,
without a GC’s pressure control device monitoring the common
junction point, the individual column flows cannot be
controlled directly by the GC. The GC can only control the inlet
pressure of the upstream column whose inlet end is attached to
a GC’s pressure control device. A column flow calculator
available from Agilent, and provided with Agilent capillary flow
devices, is used for determining pressures and flows at this type
of junction.
Some pneumatic setpoints change with oven temperature
because of changes in column resistance and in gas viscosity.
This may confuse users who observe pneumatics setpoints
changing when their oven temperature changes. However, the
flow condition in the column remains as specified by the
column mode (constant flow or pressure, ramped flow or
pressure) and the initial setpoint values.
To configure multiple columns
To configure multiple columns, repeat the procedure above for
each column.
These are the available choices for Inlet, Outlet, and Thermal zone.
Some will not appear on your GC if the specific hardware is not
installed.
Table 1 Choices for column configuration
Inlet Outlet Thermal zone
Front inlet Front detector GC oven
Back inlet Back detector Auxiliary oven
Aux# 1 through 9 MSD Aux thermal zone 1
PCM A, B, and C Aux detector Aux thermal zone 2
Aux PCM A, B, and C Aux 1 through 9