Troubleshooting "Vacuum Limit Not Reached" Error in Agilent LC Pumps

Answer

This Information Applies To: Agilent G1311B/C, G7110B, G7111A/B, G7112B, and G7120A Pumps and Agilent G7122A, G4225A, G1379A/B, and G1322A Degassers

Issue

The error message "Vacuum Limit Not Reached" will appear if the degasser does not reach a preset limit (default value is 100 mbar) in a predefined time window (default 8 minutes after powering on the module).  This may happen for many reasons.

One reason may be due to the condensation of vapors from volatile organic solvents. The vapors can condense in any part of the degasser and not restricted to any component. As such, the vacuum chamber, vacuum tube or the vacuum pump may all experience vapor buildup. If this occurs in the vacuum pump, it makes it less efficient to remove the air and achieve the 100 mbar level in time. It doesn’t happen often but the vacuum pump can totally fail and not turn on at all. This is easy to determine as no sound will be heard when the module is powered on.

The vapor can also cause cracks or fissures to develop in the vacuum tubing thus making it impossible to ever achieve the preset vacuum level.

The vacuum chamber may also develop condensate buildup, which will require a longer time to evacuate thus giving the error. In some rare cases, the chamber may even develop a crack.

In addition, other internal components can fail in rare cases, but in this case it is better to contact an Agilent Support representative.

The external degassers will not give "Vacuum Limit Not Reached" messages as they aren’t connected to Controlling software or Lab Advisor. The red error light will go on to indicate a problem. In addition, if a remote cable is connected to the pump, it will also turn all the modules red. Whether this cable is connected or not is optional.

Steps to follow

• To avoid this problem when using a built-in degasser, we recommend not to turn off the pump at all.
• If you must power off the pump, make sure to flush out the volatile solvent with isopropanol (IPA) thoroughly before doing so. In case, there is condensate buildup, which causes a vacuum timeout, an evacuation mode is available for 1260 Infinity II and 1290 Infinity pumps to recover from this problem (not applicable for external degassers and 1260 Infinity pumps). Just use the latest Lab Advisor, connect to the instrument, navigate to Instrument Control, toggle the evacuation mode on as shown in Figure 1, and follow the onscreen instructions:

Figure 1: Where to start the Evacuation Mode with Lab Advisor.

• For internal and external degassers alike, another option is to switch on the module, wait until the degasser goes into error and then restart the module. Doing so a couple of times may be sufficient to remove any condensate that may have formed. 
  Note: The G1322A has some advantages over internal degassers for solvents with low boiling point. The tubing is not that porous and the vacuum level is not as high as the internal degassers, thus less solvent vapor will condensate in the chamber. The G1322A also has two different modes of action, even if there is condensate, it will be removed more efficiently.

If you cannot resolve the issue, contact your local Agilent Support representative for more help.

Learn how to effectively troubleshoot your Agilent LC System: HPLC-0GEN-2201e - Chromatographic Troubleshooting for HPLC e-learning course available from Agilent education