Varian 450-GC, User Manual

Page: 102 / 205

Injectors – 1177 Split/Splitless Capillary Injector
Page: 162 User Manual 450-GC Varian, Inc.
The Type EFC21 status field displays the actual column pressure (in the units
chosen in Setup), calculated column flow rate, calculated column linear velocity
and the split ratio. The split ratio status is either off if the split state is set to
OFF, or a whole number.
The lower part allows you to view/edit constant flow mode.
The following screen is an example of a type EFC21 method.
Constant Column Flow
Type EFC21/EFC25 with the 1177 will automatically build a pressure program
to keep the volumetric column flow rate constant during temperature
programming of the column oven when Constant Flow is selected.
The same general guidelines should be followed for all injection modes. If the
column is operated isothermally then the pressure should be kept constant. If
the column is temperature programmed then the pressure can either be held
constant or programmed. Programming the Injector pressure generally has no
significant impact on chromatography, other than a slight reduction in analysis
time. In some instances resolution may either improve or degrade depending
on the settings. A technique called Pressure Pulse is also available for use with
Constant Flow programs with Type EFC21/EFC25. Use the following guide for
setting Injector pressure and/or building a pressure program.