Chromatography Forum

Hello,

I just recently started a new position, and it's been a few years since I've vented an MS. It's a 6890 5975.

I started to vent Friday afternoon, I left for the weekend, and came back this morning to see the dialogue box says:

"Vent Cycle Complete
Turbo Pump - Off
Turbo Pump Speed - Actual 0.0%
MS Source Temp - 48C
MS Quad Temp - 35C"

There's two big buttons that say "vent" and "pump down," and then Reconnect, Close, Help, at the bottom.

Is it ok for me now to power off the MS and open the vent valve? The screen on the MSD still says "Agilent 5795 MSD vent prepare . . ." and that's throwing me a little. I thought I remember ChemStation telling me that it's ok to turn off the MSD in a dialogue box.

Also, at what points do I turn off the rough pump when venting and when pumping down?

Thanks!

Sorry - 5975 is too new for me. But you are correct that the software for the older GCMS units had a built-in program for both venting and pump down, assuming that the newer software had that too.

That message is one of the quirks of the MS software : asking if you want to vent even though the MS is already vented.
As long as the turbo speed is close to zero and the source / quad temperatures at ambient, then simply power off the MS and you will hear the foreline pump stop.
Then open the vent valve to complete the vent cycle.

That message is one of the quirks of the MS software : asking if you want to vent even though the MS is already vented.
As long as the turbo speed is close to zero and the source / quad temperatures at ambient, then simply power off the MS and you will hear the foreline pump stop.
Then open the vent valve to complete the vent cycle.

Just one small caveat: if the foreline pump is plugged into the wall rather than the MSD, you will have to turn it off manually.

When your instrument says temps are <100C and turbo is at 0% but rough pump is still running, it means "vent prepare cycle" is complete, meaning you can complete the vent cycle. Turn off MSD and rough pump will turn off (as mentioned, if it's plugged into the wall you'll need to turn it off manually).

Then finish the vent cycle by truly venting it using the vent valve. Once at atmospheric pressure, it's technically vented.

The biggest thing to avoid is letting air in while the turbo is running, it may damage it. If you have a oil diffusion pump instead of a turbo, make sure that's off and cool as well.