A $5,000 Mistake

23 11 2010

All photos.

Last night I made a $5,000 mistake.

Do you see the problem?

I disassembled this butterfly valve a month ago for cleaning. Apparently when I put it back together I alligned the indicator perpendicular to the flap when it should have been parallel.

Last night I was doing a vacuum check with the clean chamber:

I set the butterfly valve to what I thought was full open (but was actually full closed!)

Do you know what happens next???

I turn on the vacuum pump. The turbopump goes to full speed.

Now the butterfly valve is actually closed. Which means the vacuum can’t get to the chamber.

Which means the chamber is at atmospheric pressure.

Then I turn the butterfly valve….

TTHHHHHWWWWOOOMMMMMPPPPPPP

Apmospheric air slams into the full speed turbopump, and it makes a bad sound.

Then I smell smoke..

And now the turbopump won’t spin up all.  I likely ruined the turbopump’s rotor – the most expensive part of the pump. Likely repair:

Worst case $5,000.

Likely case $3,000.

Best case $1200.

When I opened the valve I instantly knew what was happening, but it was too late.

I can’t believe I broke the pump AGAIN. Really heartbreaking, especially because I knew to avoid this specific condition.

The repair will likely take a month. I’m going to ship the pump out and…

I’ll be traveling in december.

I imagine the cheapest way out is to buy a used turbopump like mine to scavenge it’s rotor. Here it is:








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