Preventive Maintenance
Packed column inlet
Caution
Column flow is interrupted while changing septa; since some columns may be damaged at elevated temperature without carrier flow, cool the oven to ambient before proceeding.
WARNING Exercise care! The oven and/or inlet or detector fittings may be hot enough to cause burns.
Turn off carrier flow and decrease head pressure to zero. Remove the septum retainer nut and old septum. Insert a new septum. Replace the septum retainer nut, tightening it to finger•tightness(as tight as possible by hand without using any kind of tool). Do not overtighten; the retainer nut is spring•loadedto provide sufficient pressure for sealing. Restore carrier flow.
Insert/liner care
Cleaning inlet inserts and/or liners is discussed under Liner and/or insert care, later in this chapter.
Leaks
Leaks in the gas plumbing system can affect chromatographic results dramatically. The following procedure checks the flow system up to but not including the column connection. If this portion of the system proves to be leak free, refer to procedures later in this chapter to leak•checkthe detector.
1.Turn off detectors. As necessary, set oven and heated zone temperatures to ambient and allow zones to cool. Turn off gas supplies at their sources.
2.Remove any installed column and cap the inlet at its column fitting.
3.Turn on gas to the inlet at its source and adjust its supply pressure to 344 kPa (50 psi).
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