Epc Inlet; Split Mode Operation; Pulsed Split Mode - Agilent Technologies 6890 Series Service Manual

210 Split/Splitless Inlet

EPC inlet

EPC inlet

Split mode operation

For an EPC inlet in split mode, the proportional valve, PV1, is a mass flow
controller for the total inlet flow as measured by the flow sensor, FS. V is an
on/off valve which is turned on to allow flow out of the split vent. PV2 is a
back pressure regulator controlling the inlet pressure as measured by the
pressure sensor, PS. SPR is a calibrated regulator/frit which is used to control
the septum purge flow.
Flow
limiting
frit
Proportional
valve1
Safety shutdown mode:
Proportional valve1 closed
Proportional valve 2 open
On/off valve open
Figure 210-1

Pulsed split mode

For EPC inlets in this configuration, the split flow and the column pressure
(flow) are programmed up to a higher value prior to sample injection. The
2 of 30
Total flow
control loop
Septum holder Pressure
FS
104 mL/min
Flow
PV1
sensor
EPC control split mode flow diagram. 100:1 split ratio
Inlets
Agilent 6890 Gas Chromatograph Service Manual
Septum purge
regulator
sensor (not adjustable)
~3 mL/min (He, N
PS
SPR
~6 mL/min (H
Column head pressure
control loop
V
Inlet vent flow (split)
100 mL/min
Valve PV2
Proportional
open
valve 2
To Detector
Septum purge
, AR/CH )
2 4
)
2
Jun 2001