Agilent Technologies 7820A Manual page 223

Maintaining Your GC
• Review the Maximum Bead Voltage setting and adjust, if
necessary.
• Review the Dry Bead and Auto Adjust Bead settings.
Restore normal NPD operating gas flows.
18
19 With all gases on, heat the detector to 150 °C and hold for
about 15 minutes, then increase the temperature to 250 °C
and hold for 15 minutes.
Increase the temperature to operating value (310 to 320 °C
20
recommended). Allow 15 minutes for equilibration.
21 Check the NPD leakage current. (See
Leakage Current"
installation or see the
22 If using an Agilent data system, connect to the instrument.
23 Restore the analytical method. Confirm the detector
hydrogen, air, makeup gas flow rates.
Start the Adjust offset process. Enter the desired offset in the
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Target offset field. The default offset is 30 pA for white or
black beads. For white and black beads, an offset of 25 to
30 pA is sufficient for most applications. The bead life may
be shortened at a higher offset.
Reset the bead counter. See
25
Operation Manual.
"To Check the NPD
on page 230.) If > 2.0 pA, verify bead
Troubleshooting
To Reset an EMF Counter
11
Maintaining the NPD
manual.
in the
223