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.
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Nikelopez
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Vacuum Pump

Post by Nikelopez »

I would highly appreciate anyones opinion. I was looking for a vacuum pump and stumbled upon this model. But before I purchase I would your guy's opinion on this.
Its speed displacement of 14.1 CFM and an ultimate pressure of 1x10-4 Torr.

(Leybold D16 D16A Trivac Rotary Vane Dual Stage Mechanical Vacuum Pump)

http://www.pchemlabs.com/product.asp?pid=650

Any opion appreciated.

Thank You,
Nikelopez
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Tyler Christensen
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Re: Vacuum Pump

Post by Tyler Christensen »

It's a decent pump, although the price is far more than I'd suggest unless you have the money and want a pump that you know will come in good shape. You can get one on ebay for a tenth of that price although it probably won't come with a guarantee or warranty.

Keep in mind the 1e-4 torr rating won't actually be possible, that's just the rating when the inlet is capped off with a gauge, the moment you put a chamber on it you won't get that far or even approach it probably.
Nikelopez
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Re: Vacuum Pump

Post by Nikelopez »

Yes the price on the new one is quite a lot. However I just put this as an example because, i found the same model at an store near where I live selling it for 150. It looks to be in good form. I was just asking because I debating over whether or not it will help me and my partner get a vacuum great enough to achieve fusion.
Tyler Christensen
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Re: Vacuum Pump

Post by Tyler Christensen »

If in good condition it'll certainly get you to demo fusor pressures. Nearly everybody here (I'm not sure of anyone who uses a mechanical pump to get their actual fusor running) has a high vacuum pump stage after the mechanical pump, either diffusion or a turbo pump. Even if the mechanical can pull low enough for fusion, it'd do it so slowly you wouldn't realistically want to use it for it.
Nikelopez
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Re: Vacuum Pump

Post by Nikelopez »

I believe you sorta answered my next question. What I had in mind was using this mechancial pump along with a diffusion pump and a micromaze for actual fusion. But I'm not qutie sure if it'll be enough. But what from you recently stated I'm inferring it should do the job.
John Futter
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Re: Vacuum Pump

Post by John Futter »

NIKELOPEZ
These are very good pumps and has more than enough capacity for any fusion project.
Tyler is also correct a very good one running on our vac systems @ work gets around 3 by ten to the minus three millibar after a couple of weeks working as a backing pump on a 1000l/sec turbo pump.

So there is enough for demo mode, probably not enough for real fusion mode, but a diff or turbo pump will get you there just like that.
PS that pump is suitable for up to 500l/sec diff pumps or 1000l/sec turbo drag pumps.
Nikelopez
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Re: Vacuum Pump

Post by Nikelopez »

Thank You both,
Mr. Futter and Mr. Christensen

I think thats what ill end up doing. Using this pump for demo mode and for real fusion use it as well along with a diffusion pump and a micromaze.
John Futter
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Re: Vacuum Pump

Post by John Futter »

Nikelopez
you will not need the micromaze unless you want to recover some of the D2.
But I di recommend a foreline trap to keep the backing pump oil vapour out of the diff/ turbo.
yes the micromaze will do this as well but infinitely more difficult to clean.
Most forline traps use alumina beads that are not that expensive but if you are poor and have a furnace heating them to around 600-800 degrees celcius makes them as new
Tyler Christensen
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Re: Vacuum Pump

Post by Tyler Christensen »

I don't have any traps in my diffusion system anywhere and haven't had any problems with pretty heavy use over the last year. I think quality oils is sufficient to not need traps for fusion work, at least in my experience. Of course if you have the extra money for one, might as well stick it in.
Wilfried Heil
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Re: Vacuum Pump

Post by Wilfried Heil »

These are great pumps. Try to get one of the newer "B" series like a Trivac D4B if possible. The older "A" series is just as good, but it may become difficult to find replacement parts for it later.

I would always use a foreline trap on the pump to prevent oil backstreaming into the chamber. You also need an oil mist filter on the exhaust of the pump. Plan for 2-3 oil changes with new and clean (dry) oil.

It is funny that a lot more of these pumps are available in the US than in Germany. They are used extensively in the semiconductor industry.

A smaller pump would also work, unless you plan to have a really big chamber. It makes a lot less noise and uses less electricity. The one that I use on the fusor is a Trivac D1.6B, with no additional turbo or diffusion pump needed. It reaches a base pressure of 3 mTorr in just a few minutes. I suppose that John's accelerator chamber is a lot bigger than ours.
myID
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Re: Vacuum Pump

Post by myID »

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
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Doug Coulter
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Re: Vacuum Pump

Post by Doug Coulter »

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!
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Richard Hull
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Re: Vacuum Pump

Post by Richard Hull »

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
richnormand
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Re: Vacuum Pump

Post by richnormand »

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
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Re: Vacuum Pump

Post by lutzhoffman »

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.
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