36 Agilent 7890 Series Troubleshooting
2 ALS and Detector Symptoms
NPD Adjust Offset Process Fails
• Inspect the jet to see if it is clogged. (See To Check for a
Plugged NPD Jet.)
• Measure the actual detector flows. (See To Measure a
Detector Flow.) If the hydrogen or makeup flows are zero or
much lower than the displayed flow, suspect a plugged jet.
• Check the condition of the bead. Replace if necessary.
• Verify that the flow settings are correct. See Flows,
temperatures, and bead information.
• If the process still fails, there could be a large leak in the
system. This causes measured flow rates to be different from
actual flow rates. Thoroughly leak check the whole system,
especially the detector column fitting. (See Checking for
Leaks.)
• Set the equilibration time to 0.0.