Agilent Technologies 7697A Advanced Operation Manual page 49

Advanced Operation
If the initial vial pressure is low, the HS will make
adjustments.
• The final vial pressure cannot be < 1 psi (6.9 kPa) at
NTP.
• When using the constant volume vial fill mode, it is
possible to develop insufficient vial pressure. If the vial
pressure at the start of sampling would result in a final
sample loop/vial pressure < 1 psi (~7 kPa), the HS will
stop sampling when the sample loop/vial pressure reaches
1 psi.
How the HS calculates the default sample loop fill parameter The
HS takes vial size and atmospheric conditions into account
when calculating the default sample loop volume.
Vial Size Absolute Pressure
10 mL Final Pressure - 2/3 initial pressure
20 mL Final Pressure - 5/6 initial pressure
NTP pressure displayed on the instrument is Absolute
Pressure - 1 standard atmosphere.
Custom
In this mode, you can set the rate at which the loop fills,
the final sample loop pressure, and a time for the loop to
equilibrate after filling. Refer to
Loop fill ramp rate: The rate of pressure decay from the vial
and through the loop. If you suspect excess sample is being
lost during loop fill, lower the flow rate.
Loop final pressure: Since the sample loop and vial are
connected, this is also the final vial pressure. The HS cannot
pull vacuum on a vial.
• In general, set a value > 7 kPa (1 psi).
• The final pressure should provide enough pressure drop
from the initial value to make sure the sample loop is
filled.
Method Development
Ramp Rate
40 psi/min
20 psi/min
Figure 12 as needed.
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