Split/Splitless Inlet
210
EPC inlet
split ratio remains constant due to electronic control. The actual flow rate
through the inlet is much higher during the injection period, transferring the
analytes quickly onto the column which minimizes sample losses that can
occur in glass inlet liners. After the pulsed time expires, the split flow and
column flow are returned to the lower flows selected for best chromatography.
Splitless mode
For an EPC inlet during splitless injections, PV1 is used to control the inlet
pressure as measured by PS. V is an on/off valve which is turned off so there
is no flow out of the split vent. PV2 is turned on at a nominal value so that
there is no back pressure on V. FS will still be measuring flow, but it is no
longer used to control PV1. In this configuration, the total flow into the inlet
is the column flow + septum purge flow. At the user specified purge time, the
inlet control is returned to split mode (see Figure 210-1 ) to allow the inlet to
be purged.
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Inlets
Jun 2001
Agilent 6890 Gas Chromatograph Service Manual