Venting Residual Vial Pressure - Agilent Technologies 7697A Advanced Operation Manual

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How the 7697A Headspace Sampler Works
loop equilibration, the HS six port valve switches to the
inject position, and the HS injects the sample into the GC.
The HS does not send a Start command to the GC. After the
inject time elapses, the six port valve returns to its original
position. The vial remains on the probe. The vial can be
vented (while the injection occurs) or remain pressurized.
The HS repeats the pressurization, extraction, injection, and
optional vial venting for each of the extractions specified in
the method. During the final concentrating injection, the HS
sends the start signal to the GC. The HS vents the vial
(optional), removes it from the probe, and returns it to the
tray or carousel.

Venting residual vial pressure

Regardless of the type of extraction performed, the HS can
vent residual pressure from the used sample vial out of the
Vent port on the HS back panel. This venting prevents a
pressurized vial with potentially noxious contents from being
left in the sample tray or in your lab. This venting occurs
during the injection time for each current sequence entry.
You can disable this feature.
When performing concentrated extractions, you have an
additional parameter available: you can vent the vial between
concentrating extractions as well as during the final
injection.
Advanced Operation 25