Chromatography Forum

Hello all,

This site seems like a great resource. I really hope that I can help contribute info in the future. Right now, though, I am in need of some help.

My employer has put in in charge of LC repairs. I have almost 5 years experience at this kind of thing, so I feel comfortable doing pretty much anything. Like I read somewhere on here I'm "a guy with wrenches".
So, my current problem is that one of our Agilent 1100 series Degassers (G1379A) seems to not be working. I couldn't find anything on Agilent's website to help me.

The vacuum pump will run for the 8 minutes initialization, and shut off. The light goes red, and everything stops running. I took everything apart, and there was some liquid in the vacuum lines (Acetonitrile, our main mobile phase solvent). I have followed the Troubleshooting guide in the manual, and I think its the Sensor. Of course Agilent doesn't sell this peice by itself, it comes paired with the control assembly, and costs about $900. I'm pretty sure ours is no good, it has an almost constant output of about 3 volts (DC).

My real question here is whether or not there should be any liquid in the vacuum lines at all. I would hate to spend the $900, install everything, and break the new sensor by filling it with solvent.

Is there any other way to check if the vacuum chambers are good without the sensor operating correctly? How can I dry all that stuff out? Any advice would be greatly appreciated.

Thanks in advance,
Greg K.

If you have a liquid in the vacuum chamber (not only in the gas permeatable tubings) there is a leak inside the vacuum chamber. Try to locate it. And the vacuum pump of the degasser stops automatically if it can not reach the setted vaccum after few minutes (I think it was 5 minutes). May be the sensor is not the problem. If there is a leak this is the problem...

Some series of vacuum degassers had problems with (probably) incorrect sensor setting. Agilent issued a solution for correction. It consists in new setting of potentiometer. Try to ask for service.

Liquid in tubes is OK.

Did you get any error messages in the ChemStation? Check the log books to see if a specific error code is recorded.

Otherwise, like others have said, liquid inside the chamber is not a good sign. Check all the connections, and maybe try to draw some liquid through each of the channels (use a syringe) to see if you can spot a leak. Unfortunately, the coil of tubing inside the degasser is quite large, and if one of those strands starts to leak, it probably cannot be fixed.

There are a number of suppliers who carry used Agilent parts. I can give you a phone number/reference if you don't know anyone locally.

Thanks for the quick replies!

Liquid is in the chamber and in the vacuum tubes leading from the chamber. I have not opened up the chambers yet, I'll try that tonight. Could liquid have moved from one chamber to the other, or are both bad? I guess I could open them up and draw liquid through and see if either or both leaks...

mbicking - my boss seems to prefer to order from the manufacturer, but if you know somewhere else to get them, I'm all ears. It's always a good idea to save the company money.

The reason I think its the sensor is that Agilent has a way of troubleshooting which component is bad by reading the mV signal from the sensor. Its supposed to start at about 2.5V and drop to 500mV as vacuum is reached. The reading I get stays steady around 3.5V. I know the vacuum is working, I can remove the vacuum tube and feel it pull.

I'll try opening the chambers up, and report what I find.

Thanks again!
-Greg K.

how old is this system? is it the standard degasser, or the micro version?

I believe the channels are all part of the same vacuum chamber; that is, I don't think each channel has a separate connection to the pump (but it has been a while since I looked). So liquid could come from any of the channels. You will just have to take it apart to see.

Regarding spare parts, there is now an entire "industry" of service and parts suppliers. Most of them are ex-Agilent service engineers who either retired, or were retired by Agilent , and now work for themselves. Many offer their own service and support contracts, and most have hundreds of spare parts. Many have years of experience, often more than Agilent has with their current staff (we could spend a long time discussing this situation, but it's all too common these days).

The biggest inventory is in GC, where the 5890 is no longer serviced by Agilent, but my local guy has racks of 1050, 1090, and 1100 parts. So, there is a good chance you can find something used if you really need it.

When you are ready to explore this option, contact me privately.

I've had to replace some vacuum tubing myself on some 1050 degassers. I got some from the auto parts store, but finally was able to locate an agilent part number. I'd also guess you have a slight vacuum leak, maybe a cracked tube.

Have you tried asking agilent for the price on an exchange degasser?

We had a degasser fault (vacuum chamber) and it was around the same price just to get an exchange rather then a new chamber and have to fit it...

Also there is a company called Crawford scientific that sell agilent spares... They are sometimes cheaper than buying direct from Agilent..