Filling The Sample Loop - Agilent Technologies G1289 Operating Manual

Introduction to Headspace and to the 7694 Headspace Sampler
Principles of Operation
vial. The pressurization valve opens, allowing gas to enter the vial for the
pressurization time. The valve then closes again.
Carrier
gas flow
Auxiliary gas
flow for vial
pressurization
Open
Closed
Carrier gas
Auxiliary gas
Figure 5. Vial pressurization. S1 is closed (vial raised on needle).

Filling the Sample Loop

The vent valve opens and the headspace gas fills the sample loop; it then vents
to atmospheric pressure through the vent outlet. A short loop–fill time
(2 to 5 seconds) may leave pressure in the loop equilibrated to the vial pressure
and allow more analyte to be injected. A longer loop–fill time
(10 to 15 seconds) will equilibrate the loop pressure to atmospheric pressure.
16
Mass flow
controller
Pressure
transducer
Pressure
Flow
regulator
restrictor
Needle
Headspace
vial
Pressure
Vent
transducer
S2
S1
6
5
1
2
3
4
Sample
loop
To GC