would this be a good vacuum pump to get?

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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frostyk72
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would this be a good vacuum pump to get?

Post by frostyk72 » Mon Mar 29, 2010 5:25 am

just wondering if this is a good vacuum pump to get.
its in my price range at moment so might grab it while i have the cash if it will do the job.

http://cgi.ebay.com.au/8-0CFM-REFRIGERA ... 414e362b04

thanks

steven w

bk8509a
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Re: would this be a good vacuum pump to get?

Post by bk8509a » Mon Mar 29, 2010 1:14 pm

Steven,

I spent 200 USD on a pump with a KF16 output/input and an oil mist filter. The pump is capable, with a fore line trap, of going to .1 micron. Right now I can get it to around 2.7 microns.

The pump you're showing pump goes to 75 microns, doesn't seem to have KF nipples, and is just as expensive. I would say keep looking, but if you're in Australia you might have a few less opportunities than we do in the USA.

To get a star mode or other interesting behavior, you're definitely going to need less than 75 microns though.

-BK

PS: Here's what I got http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0520255364

DaveC
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Re: would this be a good vacuum pump to get?

Post by DaveC » Mon Mar 29, 2010 8:40 pm

Steven -

The key phrase in a pump description is "two stage". (The fittings are something you can replace with those of your choice. KF flanges are particularly nice, though, because they go toegther quickly and without tools.)

A single stage rotary pump no matter what the design, will be limited to about 35 microns ultimate pressure. Many, just like the one you've seen on ebay, will not even reach that pressure when new. Refrigeration needs are less stringent than research needs, which includes the fusor operation.

So, Brian has good advice for you... keep looking and you will probably find something like the pump he got. Leybold, Varian, Sargent-Welch, Edwards, and a variety of others will be something worth finding. Also, look for a Steel pump casing. These will last far longer than the cast aluminum housings, unless the aluminum is sleeved for an iron or steel liner.

Dave Cooper

lutzhoffman
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Re: would this be a good vacuum pump to get?

Post by lutzhoffman » Tue Mar 30, 2010 10:09 pm

Hello:

Overall I agree with the previous postings. This said the 2 stage Robinair, and the 2 stage Dayton R/AC service pumps, actually do very well. If you use good oil in them, they will give the more expensive scientific pumps a good run, for a fraction of the cost. On the Dayton that I had, the case was die cast Aluminum, but all of the important internals were steel. The whole internal steel assembly came as a field replacable cartridge, requiring only an Allen wrench, all for about 95 dollars. I would however not buy the one which you posted, as these are only single stage, and made in China, if I remember right.

The guy on the "Belljar" vacuum hobby site also liked the Robinair 2 stage line, with good results. In the end if you are patient you can pick up a name brand scientific vacuum pump, but be careful just the rebuild kit can set you back $150 or more, these parts are not cheap!

Also do not write off the old style belt drive pumps, if they are in good shape, or rebuilt they will often out perform the new direct drive style of pumps, in part because they run at cooler at 450-550 RPM, instead of at 1700+, and they tend to have a larger oil capacity.

These belt drive pumps can take longer to contaminate the oil, if you forget to open the ballast valve on a run for example. These can be rebuilt on a very low budjet if you for example make your own base, and add a surplus motor like a friend of mine did. He started with a Welch belt drive pump only, which he got for $35.00 on ebay. His pump turned out to be fine, and only needed oil.

In the end it boils down to whatever floats your boat, there are a lot of choices. I would suggest working backwards from your goal. In general a 2 stage pump, with 3CFM+ capacity is better, because then you have more choices later if you decied that you want to add a DP, or a Turbo pump. Read the prior threads on pumps, there is a lot of great info here.

Take Care....Lutz

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Chris Bradley
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Re: would this be a good vacuum pump to get?

Post by Chris Bradley » Tue Mar 30, 2010 11:31 pm

At this stage, Steven, I would just like to link you up to a past post of mine:

viewtopic.php?f=2&t=971#p3878

Basically - keep on reading and most all of the questions you've got will have appeared in other threads. If you have further questions, it is good form to add those to an older thread.

In regards that older post of mine, I am sure I can say that we are, of course, all very pleased indeed to see Tyler having come good, following his outstanding hard work. This is what is required for success, hard graft and committment. My advice: The rest will come as a matter of course and, as already well said, just take it easy and be ready to get a hold of kit as it becomes available [which, of course, requires enough pre-learning to know what is needed] and don't rush it.

frostyk72
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Re: would this be a good vacuum pump to get?

Post by frostyk72 » Wed Mar 31, 2010 3:30 am


thanks for advice guys.

will hang onto my money for a little bit longer and carefully look into what would be best buy.
more reading to do, will start sniffen through the forums later today

steven w

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