Vacuum Pump

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
myID
Posts: 139
Joined: Wed Jun 25, 2008 6:16 pm
Real name:

Re: Vacuum Pump

Post by myID » Wed Jun 16, 2010 6:13 pm

Hi-

I have been using several different Leybold Pumps- from my experience the quality is great and all the service I had from Leybold was really good- pretty expensive but I guess this could be expected... The service manuals are really helpful so you should try to find them for your pump.
I am not too familiar with prices in the US but if the pump is in good condition 150 seems OK.

Kind regards
Roman

User avatar
Doug Coulter
Posts: 1312
Joined: Sun May 27, 2007 7:18 pm
Real name: Doug Coulter
Location: Floyd, VA, USA
Contact:

Re: Vacuum Pump

Post by Doug Coulter » Wed Jun 16, 2010 6:29 pm

Great pump, but way overkill on the liters/second for a small fusor like project -- you don't need anywhere near that much of you've got a diff or other HV pump this is backing up -- the power and noise this has associated with it may turn into a pain, actually. I have an almost identical one about half the capacity and it's far too big already, and one that size that I groan at the power bills from.

The older belt driven slower pumps work fine, are quieter and use less power, but if you can get one of these cheap, by all means go for it. You might even be able to sub a smaller motor on it if you're the type to do that kind of thing -- they don't need much horsepower except when they are pulling right from near atmosphere.

I think that Tyler etc are right that no one is getting by on a mech pump alone. We use a mech pump and a too-big (3") diff pump here, both with diffoil 20 (cheap but ok) oil so no cross contaminaion is possible, but are converting that system to a 2" diff pump with DC 705 and a tiny 1/4 horse mech pump from a Leybold leak detector -- and expect that will be better sized than the overkill the former represents. Try to find an air cooled diff pump if you can -- saves tons of hassle with plumbing -- one less thing to fail which is always good in a system that tends to get more complex over time.
Why guess when you can know? Measure!

User avatar
Richard Hull
Moderator
Posts: 12431
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Vacuum Pump

Post by Richard Hull » Wed Jun 16, 2010 8:46 pm

The first amateur fusion done in a fusor in the US was done on a mechanical pump... and a refrigeration service pump at that! Not a lot of fusion, but definitely there, real and measureable. Admittedly there was a micromaze in the foreline. (usually good for about 1 order of magnitude over the mechanical pump when clean and freshly baked out.

Still, no big number fusion guys currently use a mechanical pump alone. You just have to have another pump after the mechanical pump if you want to do impressive fusion. It is not a matter of final pressure, but a matter of cleanliness that makes the difference.

With a mechanical pump only, you are on the nasty end of fusion, with as much oil and remnant gases in the chamber as deuterium fuel. Not a good situation.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

richnormand
Posts: 288
Joined: Sat Aug 27, 2005 12:30 pm
Real name: rich normand

Re: Vacuum Pump

Post by richnormand » Thu Jun 17, 2010 10:12 pm

Hi Nikelopez,

I got one of these Trivac D16 AC for free, broken of course!
The main metric roll-pin on the second rotor broke, leaving the rotor free, and the remnants of the roll-pin scored the vanes and the eccentric cylinder metal surface. That jammed the shaft and broke the motor coupling.

I got a full rebuild kit from Duniway, remachined the eccentric surface with a car cylinder hone. The difficult part was to remove the hardened steel roll-pin that was left in the blind back of the rotor.

At any rate should you decide on this pump and rebuild it I can help you with photos of the process, rebuild/user manual pdfs and such.

I typically get better than 4 mTorr vacuum (if I trust my thermocouple gauge down there) at the end of a 36" stainless flexible pipe. Its ratings are great as a fore pump for diff or turbo. The unit is very rugged and has been in use for almost two years now under pretty harsh conditions.

So, if the price is right, this is a pretty good well made pump in my opinion.

lutzhoffman
Posts: 188
Joined: Tue Dec 08, 2009 1:59 am
Real name:

Re: Vacuum Pump

Post by lutzhoffman » Thu Jun 17, 2010 10:50 pm

Hello:

Great pump, but kind of big for fusor work. Check out the pump threads its all been said before. I just want to add one note:

I found what I thought was an awesome deal on a 5CFM Leybold-Oerlikon pump a while back, that is until I priced the re-build kit at $360 US ! My father, who is a retired instrument & tool and die maker, even warned me: "The Swiss make real nice stuff, but watch out if you ever need any parts." But did I listen nooo, well you live and learn.

Now if I am shopping for used pumps, I price these first, way before I even consider buying any pump. Personally I like some of the Japanese pumps also like the Ulvac, which folks often do not consider.

Do not discount belt drive pumps either, they do have many advantages. Check out the pump threads, you will not regret it.

Post Reply