Critique this turbomolecular pump backed by Welch 1400 setup

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.
Post Reply
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by John Futter »

pictures are needed
Jerry Biehler
Posts: 975
Joined: Tue Nov 24, 2009 3:08 am
Real name:
Location: Beaverton, OR

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Jerry Biehler »

$850 for an old belt drive pump? I can find you a much newer Adexien direct drive pump tested for about $500.

Big port connects to the fusor. Small port connects to the roughing pump. So you will need and ISO-100 fitting to adapt to whatever you put on the chamber.
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by ian_krase »

That is indeed a somewhat expensive rotary vane pump. Usable ones are available for less.

That turbo pump is a total gamble. The seller hasn't tested it, and does not take returns. I would not risk it. It also does not look like it includes the controller (unless that's actually a built in controller. Read the manual.) Controller can cost as much as the pump, though if you are very good at electronics you can build your own. A totally broken pump is almost totally worthless, a worn out but not destroyed one can be repaired by a dealer (for over a thousand USD) or by you (using expert knowledge of turbo internals, careful analysis of the manual, and the blessing of Divine Providence).


UHV valves can be... problematic. They optimize UHV ability over practicality at normal vacuum levels. A fusor does not get anywhere near UHV, even beam on target accelerator will probably consider UHV to be overkill. Common themes include needing way too much force to close, only being operable with a wrench, and needing rebuild or gasket replacement after only a few dozen openings/closings. Consult the manual.


In any case you need, as others have said, to adapt the LF on that pump (if you use that turbopump) to the CF on the valve (if you use that valve).

Personally I would probably just go with a 60 L/s turbo (common and comparatively cheap from the mass spec biz, the smallest size of turbo) and a KF50 angle valve. This doesn't open to full line of sight but that barely matters.


You also need some flexible tube (either the expensive metal bellows kind or the much less expensive plastic or rubber) to connect your rotary pump to your turbo pump. And ideally a valve there as well. Conveniently, most turbos will tolerate a downright terrible vacuum (1 torr or more!) in the foreline.
Michael Bretti
Posts: 175
Joined: Tue Aug 01, 2017 12:58 pm
Real name: Michael Bretti

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Michael Bretti »

I agree with the above statements. Everything you are looking at is grossly overpriced and you can find things way, way cheaper if you are patient and look hard enough. Check ebay more, a lot more - I spent nearly half a year planning out just the vacuum system alone for my setup, including multiple CAD iterations, many, many pages of vacuum calculations, and significant budget planning, cost analysis, system optimization, and simulations, though most people building fusors don't really need this (but I would strongly recommend it.) I just finished the vacuum subsystem designing and planning a while ago, and I'm now working on the thermal management system, and the control system for automated pump-down control and monitoring. No need to rush and blow thousands of dollars when you can get everything for way less. Already the cost savings on my primary small system is on the order of many thousands of dollars, and I spent much less for my entire system than the total cost of the parts you linked to above, and has a lot of modularity and functionality, optimized for throughput and for use for a very large number of high vacuum experiments beyond just a fusor.

First, the roughing pump is way too expensive for a first fusor effort - while it is one of the more ideal ones, it is really not necessary. I am currently using a YellowJacket 93560 as my roughing pump. Brand new, it cost $350 on eBay, and I tested it down to 12.5 microns, and has more than enough overhead for even my very large 600 L/s diffusion pump. The 2.75" CF gate valve you can get much cheaper - I got a 6" throat one WITH a 6" butterfly valve for my larger system for only $100, free shipping, and in great condition. Smaller valves can easily be found for under $100. I also have a 2.75" CF manual gate valve like the one you linked to - it has an o-ring seal, so is much better suited for fusor work - chances are the one you linked to is similar, the metal-seal ones are rarer even though sellers list them as UHV. You can find valves for much less. The turbo can be hit or miss - I have never bought one myself, so I can't comment on them from eBay. Cheaper diffusion pumps will be more than enough for a fusor. For the 2.75" CF to KF25, I wouldn't necessarily go buying a bulk pack until you actually know exactly how your chamber will be built.

Again, I highly, highly recommend CADing out your system - sit down, plan, and take your time. No need to rush. Research high vacuum systems thoroughly, familiarize yourself with all the basics and standards of the field. It will save you a lot of money in the long run (of course if you have tons of spare cash to blow on whatever then this isn't much of an issue, but for most in the fusor field we operate on a very tight budget.) It is very surprising how often new people getting into the hobby will just rush to build a system as fast as they can without any effort to plan (or even study) the vacuum system. After all, it is the most critical part of the fusor setup, and often is the area people encounter the most problems and troubleshooting. If you want an example of full system planning, take a look at the walkthrough I posted a while ago in how I went about planning the system - it is very long, but there is lots of info:

viewtopic.php?f=10&t=12114

Also the walkthrough is posted here:

http://appliedionsystems.com/high-vacuu ... roduction/
User avatar
Richard Hull
Moderator
Posts: 14976
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Richard Hull »

The yellow jacket is a great pump. Mine has hit 10 microns on fusor II and fuosr III. All are correct above. A good, used and warranted 1400 might hit 20 microns and should never cost more than $150. The yellow jacket has 5 times the pumping speed!

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
Rex Allers
Posts: 570
Joined: Sun Dec 30, 2012 3:39 am
Real name:
Location: San Jose CA

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Rex Allers »

A bit on the Edwards Turbo pump. The EXT255 does have a built-in controller. The pump runs on 24 Vdc and has a serial interface where you can send commands to control the pump and read its status. I have an ETX75DX which is a smaller version of the same pump.

I really like the built-in controller but my pump runs with a very annoying screaming whine noise. As John Futter mentioned in this post:
"Rebalancing turbopump rotors / vibration analysis"
viewtopic.php?f=10&t=4087&p=26166&hilit=Edwards#p26166
this is apparently not uncommon with Edwards Turbos. Mine may be getting ready to die.

So buying a turbo pump from eBay is a very big gamble. I agree with all the thoughts other posters have provided.
Rex Allers
Jerry Biehler
Posts: 975
Joined: Tue Nov 24, 2009 3:08 am
Real name:
Location: Beaverton, OR

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Jerry Biehler »

The turbo pump is not a terrible price and like Rex says it has the controller on it, it is not that old of a pump.

And the seller has the turbo listed as used which means it must be in good working condition or he has to take it back. Ebay will enforce this. If he wants to sell it with no chance of someone sending it back if it does not work he must list it under "Condition: For parts or not working"
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by ian_krase »

Even though they say that they don't take returns?
Tom McCarthy
Posts: 405
Joined: Wed May 08, 2013 3:36 pm
Real name: Tom McCarthy
Location: Ireland
Contact:

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Tom McCarthy »

Yeah, all the sellers that say "no returns", "sold as is" etc and have their item listed in used condition have to refund you or provide returns if it's not fully functional. Ebay's definition:

Used

An item that has been previously used. The item may have some signs of cosmetic wear, but is fully operational and functions as intended. This item may be a floor model or an item that has been returned to the seller after a period of use. See the seller’s listing for full details and description of any imperfections.
Andrew Seltzman
Posts: 814
Joined: Sun Feb 01, 2004 8:02 pm
Real name: Andrew Seltzman
Contact:

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Andrew Seltzman »

I would recommend a pfeiffer duo 2.5, or pfeiffer duo 1.5 vacuum pump if you are going to back a turbo. They are nice scientific pumps with an NW10 flange and available on ebay at a low cost. The Yellowjacket pump is designed for air conditioning service and will require some adapting to provide a compatible flange.

I would recommend a pfeiffer turbo (with a 4.5 conflat, iso 63 or 2.75 conflat flanges, anything bigger is unnecessary). I would avoid the edwards turbos as they tend to have some problems.

The pfeiffer tmu 071 is a particularly nice pump with an integrated controller, and a molecular drag stage so you can back it with a quad stage diaphragm pump if you want. Here are some on ebay:
https://www.ebay.com/itm/Pfeiffer-TMU-0 ... SwA3dYfsMY
https://www.ebay.com/itm/Used-Pfeiffer- ... SwcaFZEA26
https://www.ebay.com/itm/Pfeiffer-D-356 ... SwFMdaXOGf

You can back them with any dry diaphragm pump capable of <~15torr
Andrew Seltzman
www.rtftechnologies.org
Michael Bretti
Posts: 175
Joined: Tue Aug 01, 2017 12:58 pm
Real name: Michael Bretti

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Michael Bretti »

For the YellowJacket Pump, which has a 3/8" male flare input, it is very easy to adapt to KF if you wanted to go this route. This pump can be a great low-cost pump if you are backing something such as a diffusion pump and you need more roughing throughput, though I doubt you will be using a diffusion pump as large as the one I have. For my system, I needed a KF25 flange for the roughing line, so I used the following parts, in order from the pump to the line:

1.) LASCO 17-5833 3/8-Inch Female Flare by 1/2-Inch Male Flare Brass Adapter - $11.77 on Amazon
https://www.amazon.com/gp/product/B008E ... UTF8&psc=1

2.) LASCO 17-6789 1/2-Inch Female Flare by 1/2-Inch Male Pipe Thread Brass Adapter - $4.44 on Amazon
https://www.amazon.com/gp/product/B008E ... UTF8&psc=1

3.) NW25 To 1/2" NPT (Female) - $23.00 LDS Vacuum
http://www.ldsvacuumshopper.com/nwto1fenpt2.html

4.) Teflon Tape (for the NPT threads only)

If you wanted to go to a KF10 flange, or any of the KF sizes, you can get KF adapters from LDS or eBay pretty cheap, and adjust your brass fittings accordingly. I used 1/2" adapter brass hardware to keep the line as open as possible to maximize throughput on the pumping side and make sure that the only limiting factor on pumping was the size of the inlet at the roughing pump. Richard Hull and myself have had good luck with this pump so far, could be something to consider if you want to get a roughing pump in new condition that will work well for your purposes. However, I agree with what Andrew Seltzmann suggested as well. Just a few different options to explore based on your system and budget constraints.
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by ian_krase »

Personally I don't recommend CAD for amateur vacuum systems unless you are either rich or are building complex custom parts yourself. It doesn't go all that well with the parts scrounging strategy IMO.

While Teflon tape can work for vacuum a better option maybe the use of Loctite 290 to glue the threads together. Otherwise you should use the yellow kind of Teflon tape that's used for natural gas pipes. You can solder or braze threads if you know that you're not ever going to need to take them apart.


Dry diaphragm pumps are nice because they can have your system be completely oil-free however being oil-free isn't useful or necessary for a fusor.

Nice thing about Pfeiffer rotary vane pumps is that they are much less heavy and bulky for the same pumping speed than most other vendors of rotary vane pumps. this is useful for people who work in cramped areas.
Michael Bretti
Posts: 175
Joined: Tue Aug 01, 2017 12:58 pm
Real name: Michael Bretti

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Michael Bretti »

I would strongly disagree about not doing CAD for an amateur system. I am operating off an incredibly restricted budget, and CAD had been completely crucial in not only saving a lot of money, but full optimizing my system. CAD allows you to build your system ahead of time and plan without having the physical parts actually available. You don't need money to build a system in cad and see how it will turn out, or make changes on the fly. Websites like Kurt J. Lesker and Ideal Vacuum have a huge list of free cad models available for download, including just about all of the major standard vacuum components, which can easily be modified if you find variations of the component, for example, on ebay. In addition to physical planning and saving money, it has been vital for all of the vacuum engineering calculations I needed for my system, as well as thermal modeling to plan for the cooling systems for the diffusion pump, water cooled baffle, and future titanium sublimation pump. I would recommend Fusion 360 - it is free, powerful, and one of the most important software tools I have at my disposal for my vacuum projects. CAD is a very useful and powerfull skill to have in general in engineering, regardless of the type you pursue, and never hurts to learn. If you have the time to learn it, I would recommend it. I would say personally from my experience, cad is exactly the tool for someone on a very limited budget forced to scrounge. If you need help or advice with cad, feel free to reach out to me.

For the roughing line, if you use it properly, Teflon tape is more than adequate. I would not say that using permanent solutions such as locktite for the foreline is necessary, and can be advantageous for modifying your system in the future if such permanent solutions can be avoided. However, if you will never need to take it apart or dissemble it, then gluing/soldering/brazing can be a solution to explore. However, you just never know what you might want to do in the future, and having the option to disassemble and modify it can help save money further down the line. My foreline tested down to 2 x 10^-3 Torr with the Teflon on the NPT threads (the lowest the helium leak checker I used to pump and check it would go, the line should go down further), more than enough for any basic roughing line you would be operating with.
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by ian_krase »

I should probably clarify. I don't disagree that CAD is a useful tool for complex vacuum systems or ones where you machine your own parts -- or even hack together enough of your own parts in restricted envelopes or the like.

However, for somebody who is mostly at the raw basic level of prototyping mostly out of scrounged parts, I think that stuff is often modular enough and you have to do enough labor just to get oddly-shaped stuff measured into the CAD program that CAD is of limited value. Meanwhile, you're often more making your project fit the parts available than the other way around.

(Unlike pen and paper, CAD is a whole separate skill that takes quite a bit of practice to be efficient at.)


So while CAD definitely has its place -- a big important place -- I don't think it's as valuable for the beginning fusioneer as commonly argued.
Jerry Biehler
Posts: 975
Joined: Tue Nov 24, 2009 3:08 am
Real name:
Location: Beaverton, OR

Re: Critique this turbomolecular pump backed by Welch 1400 setup

Post by Jerry Biehler »

I have one of the 071's, the older version with the 600 series drive. Pretty nice little pump.

The one thing about the pfeiffers is they are supposed to have their oil cartridge change yearly and if it has sat more then three years the bearing should be replaced. I really dont know how critical this is. I am guessing the oil starts to break down or varnish the bearing after that time period? Might be able to get away with rinsing the bearing in-situ with some filtered mineral spirits to wash out anything that might have dried before putting in a new cartridge.

Bearings are available from Alpine Bearing and you dont have to take the whole unit apart to change it. It comes out the bottom. I still need to get one for my TMU-521
Post Reply

Return to “Vacuum Technology (& FAQs)”