Chromatography Forum

Dear all,

I'm working with a GC-MS that has not been used for the past 8 years. It is an Agilent 6890-5973N. I was able to put it online and it seemed to work fine until we had a power shortage last week end. When I came in the vacuum sideplate was open, the foreline pump was on. I guess also the turbo pump was on (at low speed), but I'm not sure of that.
My problem now is that when I pump down the turbo pump reaches 100% as usual, but after 22 min it starts to decelerate slowly but constantly (when it reached 85% I vented). I have a Edwards Standard Turbo pump. The controller have 4 lights, 1 green and 3 red. I noticed now that the 3 red are on and the green one is off. I don't know how they were when the machine was working before the power shortage.
Do you know what those lights mean? do you have any suggestions to fix the problem before I decide to buy a new turbo pump? is it possible that the turbo pump is fine and only the controller is to be replaced?
Thanks in advance for your help

Francesca
University of New Hampshire, USA

I am surprised that the turbo pump worked at all after setting idle for eight years. When you say you had a “power shortage” do you mean low voltage or the power when off (no power to the instrument)?

The green light being off probably means that the pump is not functioning. Go to the Edwards Web site (http://www.edwardsvacuum.com/) and do a search on Controllers and see what you can find.

You will probably have to replace the pump and/or the controller. Look for rebuilt pumps.

Hi ods-at-pacific,

the whole building was without electricity, but I don't know for how long since it happened during the night.
Thanks for the hint, but I hoped there was something I could try to fix before buying replacements.

F

at least check first that the rough vacuum is within specification.

Did you check for large leaks in the system, especially at the transfer-line nut, and in the hose that connects your MS to the rough pump? Does the rough pump have enough oil in it (look at the inspection window).

Hi all, thanks for your replays. I found the problem, I think... Actually there were probably two problems: the PTFA valve had a leak and I tightened the column too much at the interface so it was probably cracked. Now the turbo pump is back at work!