I have before me a nearly identical pair of old turbomolecular pumps which I purchased on Ebay (thanks to Andrew Seltzman for pointing them out!) and collected this weekend. These things are massive; I think each one weighs about as much as I do. Needless to say, they are very difficult to move anywhere. I'll put some photographs up when I get a chance.
The rated pumping speed on these machines is 260 liters/sec, and each is driven via a belt by an external 1/2 HP, 240VAC 3-phase motor. I've bought a 3-phase AC drive on Ebay (for ~$25) which will give me programmable acceleration/deceleration rates and run speeds, fault detection, and 100 manual pages' worth of bells and whistles to play with. I can't wait to see and hear one of these machines spin up for the first time, but that will have to wait until I have space to build a proper test rig. In the mean time, I have a question regarding vacuum "throttling".
Ideally I'd like to mate the pump to my chamber as directly as possible for the sake of vacuum conductivity. It seems to be the consensus that one should place something like a butterfly valve between a diffusion/turbo pump and the chamber in order to avoid wasting precious D2 during a fusion run. However, as long as I have control over the rotor speed, could I not simply adjust the speed of the turbine to reach a comfortable pumping speed? As always, all insight and advice is greatly appreciated. |
2006-06-06 01:29 Monster turbomolecular pumps (Welch 3102) (Greg Courville) [Latest: 2006-06-06 18:14]