How to Troubleshoot no flow or no pressure issues: Binary/Quaternary/Isocratic Pumps - G131XX, and G711XX

This Information Applies To: Agilent G1311A/B/C, G7111A/B, Quaternary Pumps, and G1310A/B, G7110B Isocratic Pumps, G1312A/B/C, G7112B Binary Pumps

Issue:

How to diagnose no flow or no pressure issues on binary, quaternary, or isocratic pumps.

Resolution:

The following information should help you find what part of the pump is causing a flow or pressure problem.

Figure 1 and Figure 2 show the hydraulic paths of the pumps.

Figure 1 - Hydraulic path for the Isocratic and quaternary pump
1. From solvent bottles, 2. Inlet valve, 3. Outlet valve, 4. Damper, 5. To sampling unit and column, 6. To waste

Figure 2. The Hydraulic Path of the Binary Pump with Damper and Mixer

The most common places for a no flow/no pressure issue in a pump are:

1. Large leak in pump head.
2. Total blockage of the solvent bottle inlet filters (p/n 5041–2168)
3. Blocked or stuck outlet valve or inlet valve.
4. Blockage in the tube from outlet valve to the pressure damper- it is possible while reinstalling the pump head that the capillary can get crushed.

Troubleshooting steps:

Warning: Put on suitable gloves and other PPE for the solvents contained in your LC solvent bottles before starting this procedure. Opening fittings while the solvent filters are submerged in solvent will lead to solvents leaks. Ensure that enough lab wipes or other absorbent material is used to soak up any spills. Dispose of lab waste appropriately.

1. If you cannot see a leak at the bottom of the pump head when you try to purge, then most likely a leak is not the cause of the issue. Move to step 2.
   If you see a major leak from the bottom of the pump head or in the gap between the two pump head, please contact your local Agilent support representative.
   Also see the following knowledge base articles for detailed instructions on how to remove the pump head, change the piston seals, and then reinstall the pump head on the pump module:
    How to remove the pump head from an Agilent 1260 Infinity Binary, Quaternary or Isocratic Pump Module 
    How to change seals in a 1260 Infinity Binary, Quaternary, or Isocratic Pump without Seal Wash Option
    Reinstalling a pump head on Agilent 1260 Infinity Binary, Quaternary or Isocratic Pump Modules    
2. Put on gloves and cover the pump leak sensor/tray with paper towels to soak up any spills. Then disconnect the solvent line going into to the inlet valve at the bottom of the pump head. 
   
3. Does it drip freely?
   If the answer is yes, solvent filters are okay, and there seems to be no blockage from the solvent bottles to the inlet valve of the pump head, please move on to step 5.
   If no, remove the solvent filters and see if it now drips freely. If it does, replace solvent filters and go to step 5. If changing filters does not fix the issue, go to step 4.

4. In a quaternary pump, it may be the Multichannel Gradient Valve (MCGV) that has a blockage limiting your pump flow. Please bypass the MCGV.
   To bypass it, connect a solvent bottle of HPLC-grade IPA (with a clean solvent filter installed) to the active inlet valve on the bottom of the pump head using the Adapter Part Number 0100-1847 (see Figure 4). Attach this adapter to the Active Inlet Valve (AIV) shown by the red arrow in Figure 5, then attach the solvent inlet tube from the bottle of IPA to this adapter.
   If your pump has a passive inlet valve (PIV) installed, then you can connect the solvent inlet line from the IPA bottle to the PIV without the adapter, as shown in Figure 3.
    

   
   Figure 3. Passive inlet valve connection
   1. Passive inlet valve, 2. Solvent inlet tube
   
   

   Figure 4. Adapter, PEEK, female 1/4-28 to male 10-32

   Figure 5. AIV Fitting

5. Purge the pump.
6. Loosen the capillary coming off the top of the outlet ball valve (OBV).
7. Do you see any air or solvent?
   If yes, wait to see if you get a steady flow of solvent. Once established, then tighten the line to see if you have pressure and flow.
   If no, remove the outlet ball valve from the top of the pump head and go to step 8.

8. Do you see liquid filling up the well when the OBV was removed?
   If yes, sonicate the OBV in methanol or IPA as it may be sticking. (see Tip)
   If no, the inlet valve is the issue. PIVs and AIV cartridges (not the active inlet valve itself, Figure 6) can be sonicated in HPLC-Grade methanol or IPA (see Tip).

   
   

   Caution: Only sonicate the AIV cartridge if sonication of an AIV is required. Do not sonicate the body of the AIV as it will damage the electrical components of the valve.

   
   
   Figure 6. Active Inlet Valve (AIV)
   1. AIV Cartridge, 2. Active Inlet Valve body
   
   
   
9. Re-attach and tighten the valves on the pump head, reconnect capillaries, and try purging the pump again.
10. If the pump is still having issues, then it is time to replace the inlet and/or outlet valves as determined in the preceding troubleshooting steps. Please call you local Agilent Service Representative to arrange a service engineer visit to fix the issue.
11. Close the purge valve and make sure that the pump reaches pressure and is stable.  

Tips: Note: The solvent used for sonicating depends on the mobile phase. If your mobile phase contains a salt buffer, or old acetonitrile being used in the organic phase then use warm (Less than 60 °C) HPLC grade water for sonication.

It is recommended to have replacement parts on hand to fix the pump issue. If sonicating the valve fixes the issue it is likely to stick again, so users should prepare to replace the valve soon.

Learn more on how to effectively troubleshoot your Agilent LC Pump pump: HPLC-0GEN-2201e - Chromatographic Troubleshooting for HPLC e-learning course available from Agilent Education