Columns and Oven 4
Advanced User Guide 55
This completes column mode selection. Next you must specify
the inlet conditions either during the entire run (if you selected
either of the constant modes) or at the beginning of the run (if
you selected either of the ramped modes).
Setting the column parameters for constant flow or constant pressure
If the column is defined, you can enter any one of these
quantities—the GC will calculate and display the other two.
For example, you may have selected Constant pressure as the
column mode. You decide to specify, as a starting condition, the
column flow. The GC will compute the pressure necessary to
achieve this flow (as well as the average linear velocity) and
hold this pressure constant during the run.
If you select Constant flow as the mode and specify column flow
as the initial condition, the GC will still calculate the pressure
necessary to achieve this flow, but it will adjust the pressure as
necessary to maintain constant flow.
If the column is not defined, you can enter only pressure.
Constant flow can still be specified, but the GC cannot know
what the flow is.
1 Press [Col #] and enter the column number.
2 Scroll to the Pressure or Flow or Velocity line.
3 Type the desired initial value, followed by [Enter]. The GC
will compute and display the other two values. Adjust them,
if you choose to, by repeating steps 2 and 3 but note that
changing any one changes all three.
This completes setting the initial carrier gas condition.
Enter a flow or pressure program (optional)
If you selected either the ramped pressure or ramped flow
column mode, the column parameter list contains entries for
setting up a ramp program.
You begin with an initial value, either Initial Pressure or Initial
Flow, and an Initial time. At the end of that time, Rate 1 begins and
runs until it reaches Final pressure (or Final flow). It remains at
that value for Final time 1. You can then add a second and third
ramp, each consisting of a Rate, a Final value (pressure or flow),
and a Final time.
The program ends when it reaches a Rate that is set to 0 (Off).
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