Inlet Systems
Packed column inlet
When operating the inlet with septum purge, low bleed septa are unnecessary and the selection of septa should be made primarily for good sealing and extended septa life reasons.
On a periodic basis (every 1 to 2 months), the Teflon•coatedO•ring sealing the purge cavity should be replaced.
Electronic flow sensor
If Electronic Flow Sensing (EFS) is installed in the carrier gas system to the inlet, total supply flow rate through the system may be displayed (see Chapter 7, Electronic Flow Sensing, for details). This is particularly convenient in situations when carrier flow must be turned off (as when changing gas supplies, or if supplies must be turned off nightly, weekends, etc.).
Note: The EFS requires at least one hour for thermal equilibration for reliable readings.
Assuming the system to be leak•free(and if total flow is < 200 ml/min), after setting the desired column flow rate, total flow through the system should be noted via the EFS.
The original column flow rate is reestablished simply by adjusting the mass flow controller so the original total system flow rate value is displayed again.
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