valco valves
118
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Backflush of Precolumn toVent
This plumbing scheme allows slower eluting
components (end cut) which are not of
interest to be backflushed to vent. Often
a shorter version of the analytical column
is used as the precolumn. Once all the
components of interest have entered the
main column (at port 2), the valve switches,
backflushing the precolumn to vent and
reducing analysis time.
Note:
An auxiliary source of carrier or mobile
phase is required for this application.
Sample Injection
With the valve in Position A, sample
flows through the external loop while the
mobile phase flows directly through to the
chromatographic column. When the valve is
switched to Position B, the sample contained
in the sample loop and valve flow passage is
displaced by the mobile phase and is carried
onto the column.
Note:
This is especially critical for partially-
filled loops. The flow direction of the
mobile phase through the loop should
be opposite (backflush) to the flow
direction during the loading of the loop.
Detector Selection fromTwo
Columns or One Column and
Auxiliary Carrier
This unique configuration allows analyses
of different parts of one analysis with two
different detectors, without splitting or
multiple injections. For example, fixed
gases can be analyzed with a thermal
conductivity detector, followed by the
analysis of a hydrocarbon fraction with
a flame ionization detector.
Two Position Applications
6 port column switching
6 port external sample injector
4 port switching valve
CHROMalytic TECHnology Pty Ltd AUSTRALIAN Distributors e-mail:
Tel: 03 9762 2034
