
9 of 32
Jun 2001
Agilent 6890 Gas Chromatograph Service Manual
Nitrogen Phosphorus Detector (NPD)
320
Correcting NPD hardware problems
The baseline drifts (upward) significantly during an oven program
•
If the oven temperature is increasing dramatically during a run (for exam-
ple, from 50 to 350°C) a change of between 10 and 15 pA is normal. Howev-
er, if you suspect that the baseline drift is excessive, heat the inlets and
oven to a temperature above 300°C for 60 minutes to eliminate excess
baseline drift during oven programs.
•
Verify that the detector insulation is not cracked or damaged.
High detector baseline of GC at room temperature
•
Moisture in the detector can cause the baseline to be at 10s or even 100s
of pA when the detector is at a low (such as room) temperature. Set the
detector temperature to 150°C with the detector gases on. The baseline
should drop below 1 pA in approximately 10 minutes.
The signal baseline does not fall below 3 pA when the bead voltage is 0
•
The ceramic insulators may be dirty. The insulators must be very clean
for NPD performance to be satisfactory.
Содержание 6890 Series
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Страница 27: ...24 of 24 Jun 2001 Contents Contents Agilent 6890 Gas Chromatograph Service Manual ...
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Страница 195: ...260 Solvent Vapor Exit Accessory Leak testing 10 of 10 Jun 2001 Inlets Agilent 6890 Gas Chromatograph Service Manual ...
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Страница 389: ...360 Auxiliary EPC Replacement procedures 16 of 16 Jun 2001 Detectors Agilent 6890 Gas Chromatograph Service Manual ...
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Страница 479: ...520 Gases Supplying valve actuator air 14 of 14 Jun 2001 Site Preparation Agilent 6890 Gas Chromatograph Service Manual ...
Страница 485: ...530 Power Grounding 6 of 6 Jun 2001 Site Preparation Agilent 6890 Gas Chromatograph Service Manual ...
Страница 491: ...540 Instrument Specifications Detectors 6 of 6 Jun 2001 Site Preparation Agilent 6890 Gas Chromatograph Service Manual ...
Страница 492: ...600 Performance Verification How to check the performance of the 6890 instrument 610 Checkout Chromatograms ...
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Страница 555: ...840 Shutdowns 10 of 10 Jun 2001 Error Codes and Internal Diagnostics Agilent 6890 Gas Chromatograph Service Manual ...
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Страница 637: ...1110 Valves Liquid sample valves 6 of 6 Jun 2001 Valves Agilent 6890 Gas Chromatograph Service Manual ...
Страница 647: ...1120 Valve Box Removing the valve box assembly 10 of 10 Jun 2001 Valves Agilent 6890 Gas Chromatograph Service Manual ...
Страница 675: ...1150 Troubleshooting Pressure check 6 of 6 Jun 2001 Valves Agilent 6890 Gas Chromatograph Service Manual ...
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Страница 717: ...1225 Main Board 6890N Fuses 6 of 6 Jun 2001 Electrical Agilent 6890 Gas Chromatograph Service Manual ...
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