230 Cool On-Column Inlet
Theory of operation
2 of 20
Jun 2001
Inlets
Agilent 6890 Gas Chromatograph Service Manual
EPC inlet
An EPC controlled PCOC inlet is a forward pressure regulated system that
provides flow to the column. A pressure sensor is located just ahead of the
inlet and with the proportional valve forms a closed loop electronically
controlled system. In addition, a flow limiting frit (750 mL/min at 50 psi) is
located at the pneumatics entrance. A septum purge regulator (SPR)
maintains septum purge flow between 7 and 15 mL/min.
Figure 230-1 EPC control
Flow
limiting
frit
Proportional
valve
Pressure
sensor
Septum holder
Septum purge
regulator (not
adjustable)
PS
SPR
Inlet pressure
control loop
To De tector
Spring and
alignment insert
Purge Vent Flow
15 mL/min
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