Cryogenic Operation; Cryogenic Setpoints - Agilent Technologies 7890 Series Advanced Operation Manual

4
Columns and Oven

Cryogenic Operation

Cryogenic setpoints

148
The cryogenic valve lets you operate the oven below ambient
temperature. Minimum attainable oven temperature depends
on the type of valve installed.
The GC senses the presence and type of cryogenic valve and
disallows setpoints if no valve is installed. When cryogenic
cooling is not needed or cryogenic coolant is not available,
the cryogenic operation should be turned off. If this is not
done, proper oven temperature control may not be possible,
particularly at temperatures near ambient.
Equilibration time Set from 0 to 999.999 minutes.
Cryo [ON] enables cryogenic cooling, [OFF] disables it.
Quick cryo cool This is separate from Cryo. Quick cryo cool
cools the oven faster after a run than it would without
assistance. This is useful when maximum sample throughput
is necessary, however it does use more coolant. Quick cryo cool
turns off soon after the oven reaches its setpoint and Cryo
takes over, if needed.
Ambient temp The temperature in the laboratory. This
setpoint determines the temperature at which cryogenic
cooling is enabled.
• Ambient temp + 25 °C, for regular cryo operation
• Ambient temp + 45 °C, for Quick Cryo Cool.
Cryo timeout Cryo timeout occurs, and the oven shuts off,
when a run does not start within a specified time (10 to
120 minutes) after the oven equilibrates. Turning cryo
timeout Off disables this feature. We recommend that it be
turned On because cryo timeout conserves coolant at the end
of a sequence or if automation fails.
Cryo fault Shuts the oven down if it does not reach setpoint
temperature after 16 minutes of continuous cryo operation.
Note that this is the time to reach the setpoint, not the time
to stabilize and become ready at the setpoint. For example,
with a cool on- column inlet and cryo control in the track
oven mode, it may take the oven 20 to 30 minutes to achieve
readiness.
Advanced Operation Manual