Agilent Technologies 6890 Series, Service Manual, Page: 236 / 867

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Jun 2001
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Nitrogen Phosphorus Detector (NPD) 320
Recommended settings
• Turn the hydrogen flow off during solvent peaks and between runs.
• If your NPD is
Off
for a long time in a high-humidity environment, water
may accumulate in your detector. To remove it:
a. Set the detector temperature at 100°C and maintain it for 30 minutes.
b. Set the detector temperature to 150°C and maintain it for another
30 minutes.
Temperature programming
The NPD is flow sensitive. If you are using temperature programming, in
which the column flow resistance changes with temperature, set up the
instrument as follows:
• With an EPC inlet, set the carrier gas in the Constant flow mode. Set
EPC detector makeup gas to Const makeup. NonEPC detectors provide
constant makeup gas flow.
• If you have an EPC inlet and an EPC detector and choose to work in the
constant pressure mode, the makeup gas should be set in the
Col+mkup = const mode.
Jets and collectors
The capillary optimized NPD is only used with capillary columns. It is shipped
with the standard jet and collector.