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View Full Version : What you really don't want to see inside your spectrometer



mike alexander
2009-Mar-10, 09:15 PM
When a turbomolecular pump on your mass spectrometer goes from 60,000 rpm to zero in a few milliseconds...
http://img7.imageshack.us/img7/2987/blownturbo008.jpg (http://img7.imageshack.us/my.php?image=blownturbo008.jpg)

novaderrik
2009-Mar-10, 09:18 PM
oops

peteshimmon
2009-Mar-10, 09:21 PM
If you procured it on your credit card you
might have some sort of cover...

mike alexander
2009-Mar-10, 09:25 PM
If you procured it on your credit card you
might have some sort of cover...

My credit card doesn't go up to $25,000.

What you can't see in the picture is the coating of fine aluminum (mixed in with some aluminium) powder covering everything.

When these puppies blow, they blow good.


I know Swift will feel sympathy pains.

korjik
2009-Mar-10, 10:41 PM
Man, all I ever see is stars.....

:D

PetersCreek
2009-Mar-10, 10:48 PM
Man, that must've been a little exciting.


My credit card doesn't go up to $25,000.

My card limit is higher than that but my single purchase authority is only $10,000. Sorry. Even if I could swing it, there's the whole losing-the-job-and-going-to-jail thing...so sorry again.

kleindoofy
2009-Mar-10, 11:07 PM
That gives "Chitty Chitty Bang Bang" a whole new meaning. ;)

HenrikOlsen
2009-Mar-10, 11:23 PM
Reminded me of this (http://ratinthelab.wordpress.com/2008/03/11/death-of-a-turbo/), they do fail catastrophically when they go, don't they?

mike alexander
2009-Mar-11, 04:21 AM
I have a shot of the pump itself. The remaining blades are welded to the housing. You can see where they softened and smeared.

The best part is, this is the second one to fail in three weeks.

Neverfly
2009-Mar-11, 04:28 AM
I have a shot of the pump itself. The remaining blades are welded to the housing. You can see where they softened and smeared.

The best part is, this is the second one to fail in three weeks.

So .. Is there any kind of insurance on these things?

mfumbesi
2009-Mar-11, 08:29 AM
I love catastrophic failures especially if I don't have to foot the replacement bill.
All I can say is ....Eish!!!

geonuc
2009-Mar-11, 09:02 AM
Perhaps I'm not up to speed on spectrometers. What's the pump for? Vacuum pump?

Nice mess, though. As a preliminary thought, I'd blame bringing aluminum in contact with aluminium. A volatile mix, those two.

Ivan Viehoff
2009-Mar-11, 12:11 PM
When I was at university, a friend was doing a DPhil in Physics on an experiment that used a laser that cost about 5,000,000. But a year after he started, it deaded itself, it did. Fortunately he was clever enough to do a theoretical physics DPhil instead.

mike alexander
2009-Mar-11, 02:59 PM
Perhaps I'm not up to speed on spectrometers. What's the pump for? Vacuum pump?

Nice mess, though. As a preliminary thought, I'd blame bringing aluminum in contact with aluminium. A volatile mix, those two.

Yes, it's a type of vacuum pump. It's basically a turbine fan that knocks the air molecules down to a second pump for removal. Turbos are second-stage pumps; a more typical mechanical pump gets the pressure down to 10-2 torr, then the turbo takes it down to 10-6 torr. Wonderful devices until they fail.

Despite the looks, the big chunks aren't the real problem. It's the fine powder you can't see but I can, and getting it off all the active elements will be a pain.

Swift
2009-Mar-11, 03:17 PM
I know Swift will feel sympathy pains.
Ow.

Dr. Egon Spengler: It would be bad.
Dr. Peter Venkman: I'm fuzzy on the whole good/bad thing. What do you mean, "bad"?
Dr. Egon Spengler: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.
Dr Ray Stantz: Total protonic reversal.
Dr. Peter Venkman: Right. That's bad. Okay. All right. Important safety tip. Thanks, Egon.



Reminded me of this, they do fail catastrophically when they go, don't they?
Yep, the nature of things turned at high rates of speed with very tight tolerances.

Perhaps I'm not up to speed on spectrometers. What's the pump for? Vacuum pump?

Yes, a turbomolecular pump is a very high end vacuum pump. My personal experience has not been at that low a vacuum, and in processes that were too dirty for them.

At the moment I fighting with a diaphragm pump used to pump slurry to our lab mill. Must be a bad week for pumps, though Mike's problem is a little more expensive.

Torsten
2009-Mar-11, 03:30 PM
Ouch.


Despite the looks, the big chunks aren't the real problem. It's the fine powder you can't see but I can, and getting it off all the active elements will be a pain.

I guess it's not a device where a can of Dust-Off fixes the problem . . . .

mike alexander
2009-Mar-11, 04:42 PM
Ouch.



I guess it's not a device where a can of Dust-Off fixes the problem . . . .

Nooo. The problem is that there are lots of active elements inside depending on being perfectly clean to generate the right fields. Even a light coating of conductive dust will bollix it good. For that matter, a fingerprint in the wrong place can seriously affect the tuning.

jokergirl
2009-Mar-11, 05:25 PM
So what and why did it happen?

;)

HenrikOlsen
2009-Mar-11, 06:49 PM
From what I've been reading, they can die that way from inhaling a too big dust particle or a grain of sand.
At 3-15 kRPM it doesn't take much hitting a fan blade to initiate contact with something else and then everything goes.

mike alexander
2009-Mar-11, 06:58 PM
Or someone bumps it. And sometimes the bearings just wear out. The pump looked like this:

http://img15.imageshack.us/img15/4659/blownturbo002.jpg (http://img15.imageshack.us/my.php?image=blownturbo002.jpg)

Maha Vailo
2009-Mar-11, 11:32 PM
Oweee. I hope no one was hurt.

- Maha (and you thought you had a bad day) Vailo

Tarkus
2009-Mar-12, 03:31 AM
Reminds me of a head crash.

Anyone remember the horror of those?

Anyone honest enough to admit they remember the 70's

Trebuchet
2009-Mar-12, 06:50 PM
Or someone bumps it. And sometimes the bearings just wear out. The pump looked like this:

http://img15.imageshack.us/img15/4659/blownturbo002.jpg (http://img15.imageshack.us/my.php?image=blownturbo002.jpg)
Somehow that made a really interesting juxtaposition with your signature line just below it! ("Oatmeal....")

Swift
2009-Mar-12, 07:21 PM
Hey Mike, how are the "patients" doing (your patience and the MS)?

mike alexander
2009-Mar-14, 09:08 PM
The field engineer will be out Monday. Lots of expensive parts were delivered yesterday, and we're all hoping the boxes won't have to be opened.



Oweee. I hope no one was hurt.

No. The housings are designed to contain such failures.

Jeff Root
2009-Mar-15, 04:25 AM
Why weren't ALL the blades ripped out? I'd expect all or none.

-- Jeff, in Minneapolis

mike alexander
2009-Mar-15, 11:03 PM
Why weren't ALL the blades ripped out? I'd expect all or none.

-- Jeff, in Minneapolis

Good question. The larger pump that 'stopped' last weekend pretty much did rip itself to shreds. The pump in the picture is quite a bit smaller, less mass to stop. Once it makes contact with the wall, I suspect it stops within a portion of a revolution. Not enough time for the second half to make it to the contact point.

When one of the big ones goes like that, it does sound exactly like a gunshot.

kleindoofy
2009-Mar-15, 11:25 PM
... The housings are designed to contain such failures.
Hope for the best, plan for the worst. ;)

Jeff Root
2009-Mar-16, 04:34 AM
I haven't flown much, but when I have flown, I've tried to get a seat
that is not abreast of or ahead of the engines. :)

-- Jeff, in Minneapolis

mugaliens
2009-Mar-17, 10:08 PM
Well, they're designed not to disintegrate upon total failure of the turbine.

Van Rijn
2009-Mar-18, 12:09 AM
Why weren't ALL the blades ripped out? I'd expect all or none.

Good question. [snip]


(Deliberately ignoring the rest of Mike's explanation . . .)

Obviously, the image is a fake! :whistle:

cjl
2009-Mar-19, 02:34 AM
Well, they're designed not to disintegrate upon total failure of the turbine.

Yep. Besides, if they did completely give out, the result wouldn't be great for anyone, whether or not they were seated next to the engines.

I try to get a seat ahead of the engines whenever possible - it's quieter in the front :)