User guide

Configuration 2
Advanced User Guide 37
A simple example
An analytical column is attached at its inlet end to a
spit/splitless inlet located at the front of the GC and the column
outlet is attached to an FID located at the front detector
position.
Since only a single column is configured, the GC determines
that it controls the inlet pressure to the column by setting the
front inlet pressure and the outlet pressure is always
atmospheric. The GC can calculate a pressure for the front inlet
that can exactly overcome the resistance to flow presented by
this column at any point during a run.
Slightly more complex example
A precolumn is followed by a AUX 1 pressure controlled splitter
and two analytical columns. This requires three column
descriptions.
The GC can calculate the flow through the precolumn using the
precolumns physical properties to calculate the column’s
resistance to flow, along with the front inlet pressure and the
AUX 1 pressure. Your analytical method can set this flow
directly for the precolumn.
For the flow in the two parallel analytical columns 1 and 2, the
GC can use the column’s physical properties to calculate the
split flow through each individual column, at a given AUX 1
pressure, with both columns exiting to atmospheric pressure.
Your analytical method can only set the flow for the lowest
numbered column in a split , analytical column 2. If you try to
set the flow for column #3, it will be ignored and the flow for
column #2 will be used.
Table 4 Analytical column
Column Inlet Outlet Thermal zone
Analytical column Front split/splitless Front FID GC oven
Table 5 Precolumn split to two analytical columns
Column Inlet Outlet Thermal zone
1 - Precolumn Front inlet AUX 1 GC oven
2 - Analytical column AUX 1 Front detector GC oven
3 - Analytical column AUX 1 Back detector GC oven