HPLC Degasser/ Gradient Pump "No Vacuum"

Question

Hello,

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.

spacefish · Accepted Answer

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.

fiezah502 · Answer

Hi,

I have the same problem as well. We are using LC 1220 Infinity series. We tried flushing the system with isopropanol for 10 minutes just in case the bubbles are present. However, this does not solve the problem. The pump failed to get ready within the period of time and at the end the pump showed "error" (red light) and machine stopped. Error " degasser cannot reach the level within the specified time" shown.

What could be the problem? We already check if there is any leaking on every tubing but nothing. All seem fine. My second guess is the degasser/pump hardware may be the broken. There was one time we keep on restarting the machine and still got the same pump error. Only after 3 hours of restarting, it finally worked ( we still don't know why this happen).

How is your HPLC now? Did it worked after you tried changing the setting as recommended by Spacefish?

gmartinetti01 · Answer

Hi fiezah,

I never ended up turning the whole degasser off, although I assume that would work if you really just need to get it running. I would like a working degasser and vacuum pump though.

We got someone from pace to look at it. The problem was a tiny leak in the degasser which the guy solved just by taking the whole thing out and tightening some screws on it. He also said when he started it up that morning that it did work without an error, but that having this error pop up for a whole day every once in a while is very common and usually caused by a TINY leak in the degasser so it's not totally sealed. I'm not sure exactly which screws he tightened on it, but maybe you can do a bit of digging from there. It's likely that. Hope that helps.

gmartinetti01 · Answer

Here is the part you are looking for (degasser chamber). It's behind your binary pump, you will have to take it apart. agilent part # 5067-4734

HPLC Degasser/ Gradient Pump "No Vacuum"

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