When bad things happen to good machines

Discussion in 'Off-Topic' started by nsaspook, Mar 22, 2015.

  1. nsaspook

    Thread Starter AAC Fanatic!

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    Stopping in a fraction of a second at 28,000 RPM

    Controller in manual so it never received a stop/brake signal during a shutdown sequence.
     
  2. paulktreg

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    Doesn't look too bad.

    An hammer and some super glue should sort it out! :D
     
  3. jpanhalt

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    Jan 18, 2008
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    What was it? A centrifugal pump?

    John
     
  4. bushrat

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    If WD-40 and duck tape cannot fix it, then it is un-fixable..
     
  5. joeyd999

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    That's a turbomolecular vacuum pump, isn't it?

    You have nicely illustrated why I don't have one installed in my shop.
     
  6. MrChips

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    A turbo pump. I have one of those running in my lab.
     
  7. Rolland B. Heiss

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    Wow! It was painful to view the image man... To use the parlance of our times, that sucks!!! Beautiful metal however but one cannot judge an element by the cover perhaps? :oops:
     
  8. nsaspook

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    I finally got to open the machine it was running in. If I get approval I'll post a short video of the machine insides. The blades that are missing in the pump flew about 10 feet inside a beam chamber destroying internal shields and sending metal bits flying.
    The Ultra High Vacuum MagLev pump is designed to take the full power of the compressor section deceleration but the side casing is an inch thick solid SS plate that is now bulged out in the middle.
    Pump Data
     
  9. #12

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    Anybody want to give me, "turbomolecular vacuum pumps for Dummies"?

    I'm reading, but this is so foreign to me!
    What is, "operating fluid"?
    Do these things only operate into a partial vacuum at their output side?
    If it can throughput 200 liters per second, liters of what? Certainly not standard earth atmosphere...
    What could possibly leak or generate 200 liters of gas per second and be called a vacuum chamber?
    The vacuum levels seem incredible, like molecules per cubic meter would be a useful label.
    Are my questions bad enough to describe how unequipped I am to understand this?
     
  10. GopherT

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    A turbo molecular pump creates a vacuum from 10^-4 torr and pulls down to 10^-7 or more.
    I've been out of the electron microscope, mass spectroscopy, ion implantation and mocvd semiconductor business for some time but that's a start. The volumes are at the rated vacuum pressure. High volume, low net mass.

    You need a rough vacuum pump to get to the pressures that a turbo can start doing something.

    The other option is vapor diffusion pump. Whole other mechanism.
     
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  11. #12

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    Finally getting a grip on it. Somewhere around 10,000 times as good a vacuum as I am used to working with, and 200 liters per second of that doesn't require a very large pipe.:p
     
  12. Wendy

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    Mar 24, 2008
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    Never messed with those. The roughing pumps were used to allow the cryopumps to take over in the sputtering machines at my old job.

    Took me a minute to recognize what I was seeing. Impressive.
     
  13. MrChips

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    [​IMG]


    http://en.wikipedia.org/wiki/Turbomolecular_pump

    It took me awhile to wrap my head around how a turbomolecular pump works.

    What is the "operating fluid"? None.
    A turbo pump has to run in a vacuum (or partial vacuum).
    You cannot run a turbo pump on its own. It would self destruct. You have to create a vacuum first using a roughing pump that brings the pressure down to below 10^-3 torr. Then you can turn on the turbo pump to take the pressure down to 10^-6 torr.

    Think of marbles floating around in vacuum. The blades of the pump literally have to hit the marbles and knock them out of the chamber towards the roughing pump.
     
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  14. #12

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    Page 31, spare parts, part number 40, "operating fluid reservoir". Seems to be about the bearing that exists in case of magnetic support failure.
     
  15. nsaspook

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    Some types use a fluid mechanical bearing on the foreline side but the one that turned into salad was a total maglev design and was completely dry with no "operating fluid".
     
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  16. KL7AJ

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    We used diffusion pumps in the UCLA plasma lab for such low pressures. No moving parts, but are they bizarre...I don't even think the inventor knew how they worked!
     
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  17. Hypatia's Protege

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    Actually diffusion pumps operate on an analogous principle -- Instead of 'batting' [the molecules] about with impellers, we drive them 'out' with (accelerated) ions -- Crudely stated, in either case, it's about increasing entropy ('chaos index', if you will) and letting 'statistics' take it from there! :cool:

    Best regards
    HP
     
  18. nsaspook

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    We stopped using diffusion pumps 20 years ago, much too messy. :D Instead of clean bits of metal exploding you have an oil film on every part of a machine from the pressure shockwave in the vacuum chamber.
     
  19. jpanhalt

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    No diffusion pump I have used (oil or mercury) ionized and accelerated the vaporized fluid. You may be thinking of an ion pump, which works differently (http://en.wikipedia.org/wiki/Vacuum_pump).

    As nasaspook said, oil diffusion pumps do contaminate a system, but nothing like a mercury diffusion pump did, even with a liquid nitrogen cooled trap.

    John
     
  20. Hypatia's Protege

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    A less frequent occurrence with the (IMO generally superior) Hg systems -- albeit nastier from a HAZMAT standpoint:rolleyes:

    Best regards
    HP
     
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