Cool On-Column Inlet Theory Of Operation; Epc Inlet - Agilent Technologies 6890 Series Service Manual

230 Cool On-Column Inlet
Theory of operation

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.
Flow
limiting Proportional
valve
frit
Figure 230-1
2 of 20
Septum holder
Pressure
sensor
PS
Inlet pressure
control loop
EPC control
Inlets
Agilent 6890 Gas Chromatograph Service Manual
Septum purge
regulator (not
adjustable)
Purge Vent Flow
SPR
15 mL/min
Spring and
alignment insert
To Detector
Jun 2001