Bent Turbopump Stators and other turbomolecular questions.

[Connor Givans]

Fellow fusioneers, I seem to have worked my way into an unfortunate predicament indeed. A small piece of wood fell into my turbopump so I decided to disassemble the unit for a teardown/removal of the blades, and decided I'd clean out the oil residue and check out the guts' quality while I did so. Surprise surprise - the upper stage stators are almost all bent, at most 1cm, usually less than that. But, there's a lot of bent blades, and the stators are made from VERY thin (alas rather flimsy) sheet-metal! The pump turned freely, but I wish to re-straighten the stators before I re-assemble the unit. (I presently have all the stages in the garage sitting in-order on their centering rings.) I wondered if anyone here on the forms has ideas (or warnings) for my stator-straightening. I also plan to clean the pump for vacuum and seal it (saran wrap & tinfoil?) until it's ready for application or controller testing.

The stator column assembled with the spacing rings outside of the rotor assembly

Secondly.... The unit says "AIRCO TEMESCAL Turbomolecular pump Type 514" and I wondered if anyone had information on this pump. It seems to be part of another system, but outside of that I am quite unsure.

Tertiarily - For the choking off of this pump, I was planning on using a KF-50 cross, but I was curious if anyone had a "better idea" for choking off the pump in a more variable manner e.g., can go to a greater pump-speed but retain the low gas flow variance a fusor demands.

Thank you all for your time,
Connor Givans

[John Futter]

Conner
The stator plates are easy to straighten as best as you can. It is the rotor that matters ie no bent fins.
Turbos need a dead space immediately above the pump ie a short piece of tube equal to the pump id and about as long as the id to work properly,
it is after this you can reduce diameter to reduce conductance. Doing the above protects the pump from bending stator plates at poor vacuum (viscous flow rather than molecular flow)

reducing rotor speed also reduces pump conductance but you will have to make your own pump controller to do this

[Jerry Biehler]

I would not buy a turbo pump this old.

[John Futter]

Nitrous
doug or whatever your name is

please change your username to your real name
and also introduce yourself before posting anywhere else as the site rules require
thank you

[Dennis P Brown]

The metal is brittle and easily fatigues leading to breakage. So, bend carefully and try not to do it too often. Since these are stationary blades, even if one or even a few do break not a big issue. The rotating blades, of course, can't be lost and any significant damage to them often means the unit isn't repairable. Cleaning should be submersion only - don't use mechanical action since that risks breaking blades. The manual (if you find one) should address that process for that pump.