15 Inlets
220 Operation Manual
About the VI splitless mode
This mode is used to concentrate sample at the head of the GC column during desorb. Purge
timing delay must take into consideration the volume of the loop or trap in the external
sampler plus the transfer line versus desorb/total flow rate. Cryo focusing is required for very
volatile samples in splitless mode.
When you introduce a sample, the split 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 split valve opens.
Splitless mode pneumatics
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. The split valve is open.
Valve
Frit Frit
Frit
Valve
EPC Module
Valve
Split Vent Trap
Gas Sampling Valve
Headspace
Purge and Trap
FS = Flow Sensor
PS = Pressure Sensor
Column
FS
PS
PS
Split
Carrier Supply
80 PSI
Septum Purge
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