Troubleshooting Agilent Pump Errors due to Blockage of a Pump Head

This Information Applies To: Agilent G1312X and G7112X binary pumps.

Issue:

A blockage before the pressure sensor, e.g. in a pump head, will not give a high pressure or overpressure system error. Instead, the pump may show one of various error messages due to the pump drive experiencing too much resistance during the piston movement:

• "motor drive power" (error ID 2041, 2042)
• "servo restart failed" (error ID 2201, 2211)
• "stroke length" (error ID 2206, 2216)
• "initialization failed" (error ID 2207, 2217)
• "home position out of limit" (error ID 2203)
• "home position not found" (error ID 2204). 

If your LC system shows any of these errors, then please follow these steps to try to locate and rectify the issue.

Steps to follow:

After each step, turn on the pump, start a normal pump flow, and then check if one of the errors listed earlier re-occurs or not.

1. Remove the capillary between outlet valve and piston 2 (shown in purple in Figure 1).
2. Remove the y-capillary going from the pump head outlet to the mixing chamber (shown in blue in Figure 1). 
3. Remove the Outlet Ball Valve (OBV, shown in green in Figure 1).
4. Loosen the Active Inlet Valve (AIV, shown in yellow in Figure 1).

Figure 1. Different parts to be checked for a blockage:
Capillary between OBV and Piston 2 (purple), Y-Capillary from outlet to mixing chamber (blue), OBV (green), AIV, and its cartridge (yellow)

If the OBV or the AIV are causing the error, you may try to clean them. Sonicate the OBV or the AIV cartridge (see Figure 1) first in isopropanol, then water and then in isopropanol, each for 10 minutes (do not sonicate the whole AIV, only the cartridge).

Caution: Remove the AIV cartridge from the AIV and only sonicate the AIV cartridge. Do not sonicate the AIV body.

If this procedure does not solve the issue, you may proceed with checking the pump head interior:

1. To check if a piston is broken or if a piston seal is somehow twisted, remove the pump head and open the pump head.
2. Check the pistons for deposited material that may be hindering its movement.
3. Check if the spring in the pump head piston housing is broken (Figure 2).

   
   Figure 2. Piston Housing of the Pump Head Assembly: The red arrows show the springs pushing back the pistons. In the right part of the image, the glass piston is visible.

4. Reinstall the pump head.

If the procedures described do not solve your issue or enable you to localize a blockage in your flow path, contact your local Agilent support representative for assistance.

Learn how to effectively maintain your Agilent HPLC: Agilent 1260 Infinity LC Systems with OpenLab CDS Learning Path available from Agilent Education