1 Reply Latest reply on Dec 5, 2018 7:05 AM by spacefish

    HPLC Degasser/ Gradient Pump "No Vacuum"



      I've just yesterday encountered a problem with our HPLC (Agilent 1220 LC model). After a full day of sample prep I found I couldn't run my sequence as my gradient pump would never switch to ready in Chemstation. Scrolling over the pump status gives the error "no vacuum" insinuating that the degasser is faulty. I called support and was told we likely have to replace the degasser.


      My question is is there anything that could cause this other than the degasser before we go ahead and replace that part? Could any tubing or frits be causing a leak that would be a much easier fix, etc? This is my first encounter having to go through repairs like this on this type of instrumentation so any help, suggestions to try, or troubleshooting tips are appreciated.

        • Re: HPLC Degasser/ Gradient Pump "No Vacuum"

          You can use Lab Advisor to monitor / set the vaccum Level for most pumps.

          This can be used to debug the problem / to check if there is any vacuum generated..

          If this error occours either the pump or the sensor might have failed or the pump is not able to reach the vacuum level set inside the firmware.


          The vaccum pump is a membrane pump, you might be able check if the membrane welded itself to the seat due to solvent vapor or if there is any other mechanical failure.. (We don´t recommend opening the instrument)



          You can get Lab Advisor here: http://labadvisor.pl29.agilent.com/latest

          The screen shown above is found under "Instrument Control"


          A temporary fix would be to set the vacuum level to 1000mbar (Ambient pressure) to get rid of the "not ready" state, however this essentially disables the Degassing of the solvents.

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