User guide

Inlets 8

Advanced User Guide 267

During sampling

Pressure upsets caused by switching valves in the external

sampler can cause fluctuations in column flow rates. To

compensate for this, the interface is flow controlled during

sampling time. The sampling flow rate is calculated from the

pressure setpoint that is active when sample introduction

begins. This flow control starts when the GC goes into the Pre

Run state (when your system is automated and the Pre Run

light is on or during manual operation when you press [Prep

Run]) and ends after the interface’s Sampling end setpoint

expires.

Flow to the interface is measured by a flow sensor and

controlled by a proportional valve.

Valve

Frit

Valve

EPC Module

FS = Flow Sensor

PS = Pressure Sensor

Column

Carrier Supply

80 PSI

Septum Purge

Gas Sampling Valve

Headspace

Purge and Trap