250 Volatiles Interface
Theory of operation
2 of 30
Jun 2001
Inlets
Agilent 6890 Gas Chromatograph Service Manual
Figure 250-1 VI flow control diagram: split mode splitless mode (Idle or after
sampling end)
Splitless mode
When you introduce a sample, the solenoid valve remains closed while the
sample enters the interface and is transferred to the column. At a specified
time after the sample is introduced, the solenoid valve opens.
Before Pre Run, when the GC is preparing for sample introduction, total flow
to the interface is measured by a flow sensor and controlled by a proportional
valve. Column flow is controlled via back-pressure regulation. See
Figure 250-1.
Sampler
Trap
Valve
open
PV2
SPR
SPR
Vent
Split
Vent
FS
PV1
Tota l f low
control loop
PS
To Colu mn
Supply
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