User guide

290 Advanced User Guide
9 Columns and Oven
Backflushing using a capillary flow technology device
Because the following capillary flow technology (CFT) devices
connect to a controlled carrier gas supply, they can be used to
backflush a column:
G2855B Capillary Flow Technology Deans Switching System
G3180B Capillary Flow Technology Two- Way Splitter (with
makeup gas)
G3183B Capillary Flow Technology Three- Way Splitter
G3185B QuickSwap Accessory
A conceptual diagram for a simple setup is shown in the figure.
After the last analyte of interest elutes, you can program a
decrease in inlet column flow with an increase in the
pressure/flow from the Aux EPC or PCM connected to the CFT
device, thereby reversing column flow and forcing the
remaining analytes off the column and out of the inlet split vent.
You can do this using a post run program or as a ramped
pressure or flow program.
To set up a post run backflush
A main advantage of the post- run backflush method is that the
GC turns off detection during this time. If using an MSD, this
helps prevent damage to the detector and is the recommended
backflush method.
Split Vent
Tra p
Inlet
Column
CFT Device
Auxiliary
EPC/PCM
Detector