power failure risk on vacuum and mass spectrometer

[Jasmine]

Deal All,

I have a question, in case there is power failure and both mass spectrometer and the rotary vane pump are off for some time, i was told that this is not good because the rotary vane pump will cause problem to the mass spec, but was not told why. Could you please explain this? How long can the power failure last without the mass spec being at risk? I am only worried in case there is power failure during sunday when no one is in the lab to inform us about the power failure. I would really appreciate your answers on this problem.

Thanks

[AICMM]

Jasmine,

The MS manifold is being pumped down by the diffusion pump which is backed by the rotary vane roughing pump. If the power goes out, the MS manifold is at a lower vacuum than the roughing pump so you run the risk of backstreaming roughing pump oil into the MS manifold and smearing oil all over the MS parts. I have only ever seen it happen once, long ago, and I had the pleasure of cleaning the diffusion pump and manifold. One way to minimize the danger is to put the rough pump on the floor (lower than the MS.)

Best regards.

[Kostas Petritis]

There are also special traps that can be put in between that almost eliminates the problem.

[Jasmine]

Thanks Kostas and ATCMM.

ACTMM, so even if there is power outtage, the mass spec will be okay for hours as long as the roughing pump is below the mass spec? You see, I am only worried of this occuring in case it happens on a sunday and I am not aware about the power outtage happening.

[Jasmine]

Dear Kostas,

Can you please tell me examples of these traps that you mentioned, how they work for protecting the mass spec, etc.

Thanks

[Kostas Petritis]

Hi Jasmine,

It is like a plastic box connected on the top of our Edwards pumps, with a capacity of about half the tank or more of our rough pump. I think that is called "baffle" but I am not sure. If you give a call to Edwards they will be able to tell you about it...

[AICMM]

jasmine,

Try the following web site for more information:

http://www.sisweb.com/index/vacuum/traps.htm

They have foreline pump traps.

Honestly, I would be less worried about the shut down you have when you loose power than the start up you have when you re-gain power. If you have a long outage and you turn on a turbo or diff stack with a loose manifold seal, you will have a good chance of having a really big leak. In my personal experience, most power outages occur 8-5 since these are the times that demand is the highest. However, if your power is really spotty, perhaps you should look for a short term UPS to prevent any issues.

Best regards.

[Jasmine]

Hi Kostas and AICMM,

Thank you both so much for your suggestions. I will look into both of them.