Replacing the Split Vent Trap Cartridge Filter on a 7890/7820 GC System

Answer

This Information Applies To:  Agilent 7890/7820 GC Systems with SSL, MMI, PTV, or VI inlets. 

Issue

Split vent trap replacement is recommended as part of the scheduled preventive maintenance. Sometimes, it has to be replaced when the inlet pressure is too high, or the split vent flow cannot be reached. 

The replacement frequency will vary with the GC application. 

For other GC models, see: Replacing the Split Vent Trap Cartridge Filter on a 8890/8860 GC System 

Items Required

• QuickPick PM kit, for split vent trap (p/n 5188-6495), includes filter cartridge and two O-rings
• Torx T-20 key 

Steps to follow

1. Set the oven temperature and the inlet temperature to 35^oC, and allow them to cool down
   
   

   Warning: The oven or inlet may be hot enough to cause burns. If either is hot, wear heat-resistant gloves to protect your hands.

    
2. When the temperatures reach near 35^oC, set the total flow to zero and turn off the carrier gas supply pressure
3. Remove the pneumatics cover to access the trap assembly (Figure 1):
   
   

   Warning: The split vent trap may contain residual amounts of any samples or other chemicals you have injected into the GC. Follow your company’s safety procedures for handling these types of substances while replacing the trap filter cartridge.

   
   Figure 1 Trap assembly.
   1. Split vent valve, 2. Knurled nut on weldment assembly, 3. Retaining clip, 4. Split vent trap screw
   
   

4. Completely loosen the split vent valve screws (Figure 1, 4) that secure the split vent valve in place
5. Loosen the screw that holds down the split vent trap and rotate the retaining clip
6. Loosed the knurled nut (counterclockwise) on the weldment assembly. This assembly contains the split vent trap
7. Lift the split vent valve and trap assembly together from the mounting bracket, and unscrew the split weldment on the filter trap assembly 
   
   

   Caution: Be careful not to stress (twist or bend) the tubing between the split vent valve and the trap as it make cause small fractures and leaks.

       
8. Open the weldment, remove the trap and the two O-ring seals
9. Seat the new O-rings on the new filter cartridge
10. Insert the new trap into the weldment. The narrow end goes toward the front of GC
11. Start closing the weldment by threading the knurled nut onto the other side. Do not tighten yet
12. Place the filter trap assembly in the mounting bracket and install the retaining clip
13. Reinstall the screws of the split vent valve
14. Fully tighten the split vent front weldment onto the trap
15. Turn on the column flow and inlet temperature and purge for 10 to 15 minutes
16. Check for leaks, see: How to Run and Interpret the Inlet Leak and Restriction Test for the Agilent 7890/8860/8890 GC Systems 
17. Install the pneumatics cover
18. Reset the EMF counter if needed
19. Restore the analytical method.
    
    

Tips: This procedure is also available in the video: Change the Split Vent Trap - GC Troubleshooting Series

Learn how to effectively maintain your 7890 GC: GC-7890-2232z - How to Replace the 7890 Split Vent Trap e-learning course available from Agilent education.