Maintaining the NPD 11
Maintaining Your GC 223
• Review the Maximum Bead Voltage setting and adjust, if
necessary.
• Review the Dry Bead and Auto Adjust Bead settings.
18 Restore normal NPD operating gas flows.
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.
20 Increase the temperature to operating value (310 to 320 °C
recommended). Allow 15 minutes for equilibration.
21 Check the NPD leakage current. (See “To Check the NPD
Leakage Current” on page 230.) If > 2.0 pA, verify bead
installation or see the Troubleshooting manual.
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.
24 Start the Adjust offset process. Enter the desired offset in the
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.
25 Reset the bead counter. See To Reset an EMF Counter in the
Operation Manual.
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