• Created : 
  • Modified : 
  • Category :  Agilent Knowledge Portal
  • Entry Type :  Article
  • Product Type :  GC Systems
  • Component :  GC Detectors
  • Product Name :  6850 GC System 6890 GC System 7820 GC System 7890 GC System 8860 GC System 8890 GC System
  • Task :  Troubleshooting
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How to Blank off a GC Detector for Troubleshooting

Answer

This Information Applies To: Agilent 6890/7890/7820/8860/8890 GC systems

Issue

Blanking off a GC detector can help locate the source of issues such as baseline noise, baseline spikes, elevated baseline, or detector output/performance issues.

Items Required

  • For Capillary Columns
    • No-hole ferrule (p/n 5181-3308)
    • Finger tight blanking nut (p/n 5020-8294)
    • Capillary column nut  
  • For Packed Columns

Steps to Follow

  
Warning: GC detectors are usually at high temperatures so make sure that the detector is below 50 °C before touching.

  1. Prepare the detector for maintenance: load the GC maintenance method.

  2. Wait for the detector to be off and cool enough to touch.

  3. Remove the column from the base of the detector: using a spanner initially to unscrew the column nut, then unscrewing with your fingers.

  4. Carefully withdraw the column. The end of the column can be left into the oven only If using helium, nitrogen, or argon as carrier gas.

     

      
    Warning: Due to risk of explosion, when using hydrogen as carrier, do not leave the column venting into the oven. Either cap the end of the column with a septum, or turn off the inlet pressure and leave the oven under 50 °C. 

     

  5. Assemble the blanking nut by placing the ferrule into the top recess of the nut. You can use the following combinations:

    • The no-hole ferrule with a normal capillary column nut.

    • The finger tight blanking nut with a regular capillary column ferrule.

    • The no-hole ferrule with the finger tight blanking nut (this option is ideal).

  6. Install the blanking nut into the base of the detector.

    • For the finger tight blanking nut, screw in finger tight. 

    • For the capillary column nut (with the no-hole ferrule) screw the nut finger tight, then with a wrench, tighten an additional quarter to half turn.

    • For packed column fittings, use the appropriate brass female blanking nut.

  7. Load the regular Acquisition Method (edits may be needed if using hydrogen carrier and the column flow was stopped). Wait until all the GC setpoints are reached and the detector is showing an output. Run the method (blank injection) and assess the detector signals for issues now that it is isolated from the rest of the GC.

  Learn how to effectively operate your Agilent GC system:
GC-0GEN-1013s - GC Detectors Theory and Operation e-learning course available from Agilent education
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