User guide

292 Advanced User Guide
9 Columns and Oven
To backflush using a ramped pressure program
In this case, the backflush occurs as part of the run, so the
detectors continue to collect data. During the backflush, you
may wish to turn off data collection in the data system.
1 Verify that all columns are properly configured.
2 Enter all method parameters for the analysis: sampler
parameters, inlet parameters, oven temperature profile,
detector flows and temperatures, and so forth.
3 Program the oven for the backflush.
• Include any temperature profile needed for backflush.
• Set the total run time to include sufficient time for
backflush.
4 Program the pressure ramp for the column installed between
the inlet and the CFT device. After the last analyte elutes or
after reaching the last temperature of interest, program a
fast ramp (for example, 30 psi/min) with a final pressure of
0.
5 Program the pressure ramp for the primary column installed
between the CFT device and the detector. The pressure
should increase slightly during the backflush duration so
that the flow into the detectors remains relatively stable.
If you turned off data acquisition in a data system during
backflush, remember to turn it on again at the end of the run.
To backflush using a ramped flow program
In this case, the backflush occurs as part of the run, so the
detectors continue to collect data. During the backflush, you
may wish to turn off data collection in the data system.
CAUTION
To avoid damage to an MSD, Agilent strongly recommends setting
up backflush as a post run event, not as part of a ramped column
program. If you still choose to backflush as part of a run, be very
careful that the flow into the MSD does not exceed the limits of the
vacuum pump.