5890 Series II GC 5972 Mass Spec Release Vacuum

Discussions about GC and other "gas phase" separation techniques.

8 posts Page 1 of 1
Our small college is in the process of getting this 5890 Series II GC 5972 Mass Spec system operational.
While testing out the pump while it was attached to the mass spec, we just unplugged it and thought that enough air would leak into the mass spec from the GC input hole.

Nope it did not. Pump oil was pulled back into the diffusion pump. We cleaned out the diffusion pump, put in new oil.

Now, how do we release the vacuum when we are done using this system?
You should read instructions manual before operating MS.
Probably there is a valve to vent MS.
There is a valve on the front of the MS that you can open to release the vacuum after "venting" in the chemstation software. I'm with dblux. If you've never worked with an ms before, be sure to read everything - no matter how trivial you think it might be.
dblux_ wrote:
You should read instructions manual before operating MS.
Probably there is a valve to vent MS.


There are software controls to vent the MS, and for the pump down.

I'm concerned that you tried to pump down without anything connected to the MS inlet, and got pump oil pulled over. Hope everything was really cleaned out very well!
I agree with Consumer Products Guy. I have lost power multiple times to my 5890/5972 and have never had the rough pump back stream to the dif stack. You must have a completely plugged transfer line and an extremely short rough pump hose.

If you did get back streaming into the dif stack you will have oil all through the MS. You will need to disassemble the source and thoroughly clean everything, plus replace the EM horn. You'll also have to change the rough pump hose and clean out the rough pump gauge assembly.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
Do the "72"s have the quartz quads? I jumped from a 70 to a 73.
If the quads are quartz, you need to be very careful cleaning them.
Yes, the '71 and '72 have the silica quads. They are a complete pain; very delicate and very, very hard to clean adequately. Makes me really miss the big ol' clunky ones in the 5970.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
rb6banjo wrote:
There is a valve on the front of the MS that you can open to release the vacuum after "venting" in the chemstation software. I'm with dblux. If you've never worked with an ms before, be sure to read everything - no matter how trivial you think it might be.


There is no valve on the 5971/5972 instruments for venting. On those instruments you went through the vent cycle in software to cool the oil diffusion pump, then once the pump and source were cool, you removed the column or slid the unit far enough away from the GC to remove the clamp on the interface and vent it there. You also had to remove the interface before you can remove the top plate and source/quad assembly. The vent valve was introduced with the 5973 models.

The rough pump should have an anti-suckback valve so that oil does not flow back up into the MS, but if they are old these can fail. Normally the helium flow of 1-2ml/minute is enough to allow the MS to come to atmospheric temperature in about 30 minutes without the backflow, but best to just remove the column when you turn off the power switch which stops the rough pump.

Do not vent the system between the rough pump and the diffusion pump, that will cause diffusion pump oil to suck back into the analyzer, and that is horrible to clean out of the system.
The past is there to guide us into the future, not to dwell in.
8 posts Page 1 of 1

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