[Sneap] Turbo pump repair

[Manfredo (IFUSP)]

Stephen

There is a way I use to clean dirty vacuum systems. Feed the system 
(your pump) with Argon
through a needle valve and pump it out on the other end using a backing 
pump through a throttle valve.
Keep the pressure in the system at ~100-200mtorr range. It is important 
to feed the system
from one side and pump it from the other. The gas is supposed to flush 
the system.
Heat the system (and/or the gas) to ~100 - 150C. Leave it pumping for 24h.
You will end up with a gas sputtered clean system and of course dirty 
oil in
the backing pump. Hope it helps.

Manfredo

Stephen Marino wrote:
>
> We have a Varian V-700HT turbo pump that needs to have its bearings 
> replaced. The pump has permanently lubricated ceramic bearings. I 
> believe it has dry lubrication - no oil or grease. We have, in the past, 
> run high currents of beam onto titanium targets loaded with tritium and 
> consequently still have some tritium in the vacuum system. Wipe samples 
> of the inlet of the pump showed 2300 dpm of tritium contamination while 
> the outlet of the pump had only 205 dpm (New York City considers an item 
> with a measurements of <1000 dpm/100cm2 to be releasable to uncontrolled 
> areas.). Simple wiping with alcohol reduced these measurements to 350 
> and 50 dpm, respectively. Unfortunately, we can't take wipe sample 
> within the pump without disassembling it even if we can decontaminate it.
>
> Varian Vacuum will repair the pump, but it will take 6-8 weeks and cost 
> over $4k. Does anyone know of a company, other than Varian, who will 
> rebuild pumps with radioactive contamination?
>
> Alternatively, has anyone tried decontaminating a pump without 
> dismantling it?
>
> Steve Marino
>
>   

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Prof. Manfredo H. Tabacniks

University of Maryland          University of São Paulo  
UMBC - Physics, #432            USP - Applied Physics Dept.
Phone. 410 455 1937             Phone. +55 11 3091 6846
manfredo at umbc.edu               tabacniks at if.usp.br
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