Could you help me judge this vacuum pump?

[Martin Shahi]

Hi everyone! I have found this vacuum pump here: http://www.ebay.co.uk/itm/ALCATEL-2008A ... 4ac702930b
and I would very much like to know what you think of it. Refurbished it should have the following specifications:
7CFM
1X10-4 torr ultimate pressure

I'm hoping to build a full fusor reactor and I would like to know if this would fit the bill with a diffusion pump as well (which I have yet to find so any help in that
area is greatly appreciated too).
Thanks!

[Nick Peskosky]

Martin,

The Alcatel 20XX series pumps are terrific backing pumps (I personally own an Alcatel 2021i) and if the pump listed in the auction runs in an even halfway decent manner you should be more than off to the races in pulling a vacuum. The inlet/outlet seem to be covered in dirty grease and the pump's exterior is a little worse for the wear but none of these cosmetic issues will ultimately impact the serviceability of the pump. My advice would be to message the seller and ensure that the pump was in the functional condition prior to having its high-vac oil drained. I word of caution, 400$ is a pretty hefty price tag for a pump in this condition especially considering the seller is charging for shipping. Even though high vacuum equipment is scarce across the pond I'd recommend you keep your eyes peeled and wait for a while until you see a pump come along in the 100-200$ price range. Lastly, refurbishing is likely not needed for Fusor applications unless the pump has a broken vane/ruptured gasket in which case you should probably search for another pump anyway. Numerous threads on this forum discuss disassembling/cleaning these pumps as well as flushing the pumps with oil in order to return them to the mTorr pumping range suitable for backing a typical diffusion pump or TMP.

[Martin Shahi]

Thank you very much for your advice! I shall ask the seller about the pump's functionality and I will try and negotiate the price down. Any advice regarding good diffusion pumps?

[Chris Bradley]

Guilty!

[Martin Shahi]

Guilty? I'm sorry I don't understand.

[Richard Hull]

Here is where a small use of the quotes or a single, self generated, sentence referencing the quilty plea might have helped. We get either a flood or a drought.

Richard Hull

[Martin Shahi]

Here is where a small use of the quotes or a single, self generated, sentence referencing the quilty plea might have helped. We get either a flood or a drought.

Richard Hull

Like this? Also do you have any advice regarding a good diffusion pump?

[Richard Hull]

I was speaking to Chris Bradley's failure to clarify. "Guilty"

Regarding advice on selecting a good diffusion pump.....No. I have no advice at all... other than that which I gave in the long FAQs I wrote a while back on diffusion pump selection, cleaning and use!!!

[Martin Shahi]

I was speaking to Chris Bradley's failure to clarify. "Guilty"

Regarding advice on selecting a good diffusion pump.....No. I have no advice at all... other than that which I gave in the long FAQs I wrote a while back on diffusion pump selection, cleaning and use!!!

I read this FAQ but unless I am mistaken I didn't see any brand recommendations in it like you wrote in you FAQ regarding mechanical pumps.

[Richard Hull]

Brands?! What does that have to do with anything? If it is a diffusion pump and the heater works, it's OK.

As noted in my FAQ, select an air cooled unit with a 2 to 4 inch throat. Big Belly Bob's diff pump is as good as the finest Varian. They are like just tubes with a heater and a jet stack dropped in them. Zero moving parts.

Richard Hull

[Martin Shahi]

Brands?! What does that have to do with anything? If it is a diffusion pump and the heater works, it's OK.

As noted in my FAQ, select an air cooled unit with a 2 to 4 inch throat. Big Belly Bob's diff pump is as good as the finest Varian. They are like just tubes with a heater and a jet stack dropped in them. Zero moving parts.

Richard Hull

Well as with most products there are brands which are more reliable than others. There are also diffusion pumps of hugely varying prices. Clearly some are more suited to this particular job than others. Such as these two:
http://www.ebay.co.uk/itm/Diffusion-Vac ... 35ca7c5fc0

http://www.ebay.co.uk/itm/Varian-VHS-4- ... 2ec8fc9cad

They probably both do a great job, but one of the two may be more suited to a fusor. I was just asking for some help, no need to be curt and short-tempered towards a complete newbie here.

[Carl Willis]

Martin,

There is little brand variation among diffusion pumps, outside of appearance.

My advice is to pick something small. You will have to buy oil for the pump, and it is very expensive, so it pays to stay on the small size. Fusor projects almost never benefit from the high speed of a big pump anyway. I see many pumps on eBay right now that are much cheaper and smaller than the two you are looking at. I see plenty of air-cooled pumps (nice for running at home, where you don't want to run water cooling lines for your pump). You should be able to find something suitable for under £150 any day on eBay, today is no exception as I look through the listings. Check out 350858658105 for an example of what I would call an ideal air-cooled diff pump at a fair price (comes with a high-vac valve as a bonus).

Many times, diffusion pumps will be sold with extras attached. Foreline, roughing, and high-vac valves are some of the nicest extras to look for. Your first link shows a water-cooled pump that comes with a baffle, a cryogenic trap, and a foreline valve. Baffles and traps are of limited value in fusor projects, and the trap can only be operated if you have a supply of liquid nitrogen. The second pump has no "bells and whistles." Just a plain diff pump offered at an exorbitant price. Both of those sellers are typical of the career-eBayer nuisance sellers who think that everything they touch turns to gold. One always has to wade through a long list of nuisance listings to find anything decent anymore.

-Carl

[Martin Shahi]

Martin,

There is little brand variation among diffusion pumps, outside of appearance.

My advice is to pick something small. You will have to buy oil for the pump, and it is very expensive, so it pays to stay on the small size. Fusor projects almost never benefit from the high speed of a big pump anyway. I see many pumps on eBay right now that are much cheaper and smaller than the two you are looking at. I see plenty of air-cooled pumps (nice for running at home, where you don't want to run water cooling lines for your pump). You should be able to find something suitable for under £150 any day on eBay, today is no exception as I look through the listings. Check out 350858658105 for an example of what I would call an ideal air-cooled diff pump at a fair price (comes with a high-vac valve as a bonus).

Many times, diffusion pumps will be sold with extras attached. Foreline, roughing, and high-vac valves are some of the nicest extras to look for. Your first link shows a water-cooled pump that comes with a baffle, a cryogenic trap, and a foreline valve. Baffles and traps are of limited value in fusor projects, and the trap can only be operated if you have a supply of liquid nitrogen. The second pump has no "bells and whistles." Just a plain diff pump offered at an exorbitant price. Both of those sellers are typical of the career-eBayer nuisance sellers who think that everything they touch turns to gold. One always has to wade through a long list of nuisance listings to find anything decent anymore.

-Carl

Thank you very much for your kind advice. Also how do you search for things on ebay, since when I search "vacuum diffusion pump" I only get 4 search results returned. Clearly I am doing something wrong, but if you could tell me how to rectify my mistake then I would be very grateful.

[Tom McCarthy]

Just look out for the voltage rating, you may already know but England and Ireland are 220v, 50 hz, unless you've got some sort of adapter which I'm not sure you can get, 110v rated pumps and equipment will be useless for you.

Just did a quick search with 'diffusion pump' and 331003911723 was at the top of the list. It's going for $99 but it's rated at 120v.

Edit: Does anybody know if it's possible to use a Variac as adapter to provide 120v to items from a 220v mains? That is if they can take the 50hz rather than 60hz if that's relevant?

Tom

[Martin Shahi]

Just look out for the voltage rating, you may already know but England and Ireland are 220v, 50 hz, unless you've got some sort of adapter which I'm not sure you can get, 110v rated pumps and equipment will be useless for you.

Just did a quick search with 'diffusion pump' and 331003911723 was at the top of the list. It's going for $99 but it's rated at 120v.

Edit: Does anybody know if it's possible to use a Variac as adapter to provide 120v to items from a 220v mains? That is if they can take the 50hz rather than 60hz if that's relevant?

Tom

Your post helped me realise why I could only find 4 results for diffusion pump; I was using ebay.co.uk instead of .com! Now when I use ebay.com I get loads more results! Thank you for this.

[Bogdan G B]

http://www.ebay.co.uk/itm/170854353765? ... 1436.l2649

Similar pump, cheaper.
Would this run off single phase?

[charlie_mccartney]

I got a Acatel 2004A with a MicroTorr 11-D diffusion pump for 300 after shipping, just wait and watch.

[Richard Hull]

Carl was right!...........Someone would show up and quote entire previous postings within a thread!!!

Please do not quote what was just posted, Martin. Folks follow threads real good here. No need to parrot others words just posted.

Richard Hull

[Ross Moffett]

You can run the motor on single phase, but you will need a motor drive unit. These can have some advantages, that you can speed/slow the pump at will using the controller. Three-phase motors are quiet, too, because there are no commutators. If you go this route, be careful as to not run the pump at low speed for too long because some pumps have lubrication issues there.. they may have some mechanical "fling" inside that sloshes oil around and doesn't work at low speeds. I work in the automation industry, and I can say that AutomationDirect is going to have the best prices you will find on new equipment in the USA, though there is some used and third-rate equipment available on eBay.

Here are some instructions for removing the "quote" button, Richard. I expect it will take less time to do that than you will spend warning people not to use it in the future.

[Carl Willis]

Does anybody know if it's possible to use a Variac as adapter to provide 120v to items from a 220v mains?

In this case--a diffusion pump heater--a cheap light dimmer can be used to control power consumption. Even in cases where the nominal heater voltage rating and the mains supply are consistent, better control of operating conditions can be had with a dimmer. Different oils boil best at different temperatures.

Variacs can also be used. In general, the same transformer can be used on both 50 Hz and 60 Hz line frequencies, albeit the tap configuration may be more restrictive for 50 Hz (more turns on the core, less output range).

-Carl