Agilent GC FID Jet Restriction Test

This Information Applies To: Agilent GC Systems with Flame Ionization Detector (FID)

Issue:

The Flame Ionization Detector (FID) jet could become clogged with ferrule material, column bleed, or heavy molecular analytes. The clogged jet will affect the flow of hydrogen fuel, which causes the FID to have ignition difficulty or flame out. This FID Jet Restriction test allows us to quickly confirm if the FID jet is restricted and maintenance may be required.

Steps to follow:

Warning: FID body, column nut, and jet are hot and unsafe to touch when heated if the detector temperature is above 60℃. Use the proper Personal Protective Equipment.

For 6890 and 7890 series GC Systems:

1. Turn Off Air and Makeup gas flows using the acquisition software or the GC keypad.

2. Turn On Hydrogen Flow and set it to 75 ml/min.

3. Monitor the makeup gas flow reading.

4. If the Makeup gas reading is higher than 1ml/min then the jet may be clogged (see Figure 1). In this case, exchange the jet, or clean it with a wire, see How to Clean an FID.

   
   Figure 1. Jet restriction test results
   1. Unrestricted jet, 2. Partially clogged jet

Tips: If the GC keypad is unresponsive, the GC could be in shutdown status. Use the Up and Down arrow to navigate to the shutdown zone, i.e. Flame. If the flame status is showing as flashing Off, the GC is in flame shutdown status. Press the Off button on the keypad to permanently turn off the flame and to clear the shutdown status. The keypad should be responsive after clearing the shutdown. This clearing of the firmware shutdown is also applicable for shut down on any pressure, temperature, or flow zones on any inlets or detectors.

For 8890, 8860 and Intuvo 9000 GC Systems:

FID Jet Restriction Test is available as a built-in diagnostic test in the touchpad or the browser interface. (See How to use the Browser Interface for 8890 and 8860 GC Systems)

1.  In the touch screen display or browser interface, select Diagnostics view. (See Figure 2)

2.  Click or press Diagnostic Tests.

3. Select either Front Detector or Back Detector.

4. Select the Jet Restriction Test.

5. Click or press Start Test.

   
   Figure 2. Jet Restriction test in the browser interface
   
   

6. Follow the instructions on the screen to get the test result. 

7. If the test fails, exchange the jet, or clean it with a wire, see How to Clean an FID.

Learn how to effectively troubleshoot your Agilent Flame Ionization Detector: GC-7890-2250s - Agilent 7890 Series GC: Flame Ionization Detector (FID) Maintenance and Troubleshooting  GC-MULTI-2250s - FID Maintenance and Troubleshooting e-learning available from Agilent education.