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Diffusion Pump Design & Construction
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Hello Group
This is my first posting to the group. I am in the process of preliminary thoughts relating to a coating system. I was looking for information to look at designing and constructing a diffusion pump verses purchasing one, off coarse sizing is part of the process to. The size of the containment is or will be 36" in diameter @ 14 inches in depth, so approximately 8.25 sq.ft. internal volume minus internal components. I have at my disposal a reasonably complete machine shop so this aspect is complete. So that being said.... 1. Is there a rule of thumb for sizing the Roughing pump for reasonable pump and makeup due to degassing time? 2. Same Q relating to the diffusion pump? 3. More Q's guaranteed, relating to instrumentation etc. Thanks and look forward to your responses. Bill |
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Ken
Hi Bill...
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Welcome to VacuumX. Good questions, some answers should be forthcoming from some of the members soon. In the mean time, there is a lot of information that you can check in the VacuumX Group's files, photo's and link's sections on the web page while you are waiting for answers. Ken Hunter --- In VacuumX@..., "B." <bill177@...> wrote:
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Aurigema, Andrew N. (KSC-ASRC-491)[ASRC AEROSPACE]
开云体育I would be more concerned about getting the chamber before thinking about the pumps.? A 36” diameter chamber is not a trivial thing.? Do you already have one ??? ??I searched ebay for a year before I found something that big to use and then it was a year more to re-condition it.? ?? ? I suggest a turbo pump for the high end and a really big bad mechanical for the atmospheric ?to low evacuating.? I run a Leybold ??similar to this ? but 3 phase.? My chamber is bigger than you are thinking about but your chamber will take a pump this big or many many hours of a smaller one.? ? Drew in sunny Florida ? From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of B. ? ? Hello Group
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开云体育Hello Actually this is in work…. Hmmm did not really think it was that lager (8.25 CuFt.) A turbo would be awesome but the cost is … well ???? So for now a Diffusion will have to do. Looking at a 6”, but will be adequate for reasonable pump downs( 1-2 hours)? Will check out your link and review Thanks Bill ? From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Aurigema,
Andrew N. (KSC-ASRC-491)[ASRC AEROSPACE] ? ? I would be more concerned about getting the chamber before thinking about the pumps.? A 36” diameter chamber is not a trivial thing.? Do you already have one ??? ??I searched ebay for a year before I found something that big to use and then it was a year more to re-condition it.? ?? ? I suggest a turbo pump for the high end and a really big bad mechanical for the atmospheric ?to low evacuating.? I run a Leybold ??similar to this ? but 3 phase.? My chamber is bigger than you are thinking about but your chamber will take a pump this big or many many hours of a smaller one.? ? Drew in sunny Florida ? From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of B. ? ? Hello Group
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开云体育Thanks Ken Yes I look forward to some input on this one. I Have been thru the groups file section & photo and found them to be very helpful. Mr. Lerch has also ?been extremely help to, but always more questions. If I buy I want to be sure that the Eq is correct for the project due to my budget. That’s one of the reasons I was looking at Diffusion design and construction, but may end up out sourcing? for both units. The chamber is in work, so one step at a time until completion. Thank for the welcome Bill ? From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Ken ? ? Hi Bill...
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Bill,
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To echo what others are likely to have said, large diffusion pumps are often available on eBay for a song. They are less desirable than small pumps, just because there are fewer amateur applications for the big ones. I've seen many of them go for less than the value of the scrap stainless. Unless you really enjoy the concept of reinventing the wheel, you would be better off by buying a large diffusion pump ready built off eBay for $100 or so, cleaning it out and applying it to your chamber. The pump oil is likely going to cost you more than the pump itself, regardless of whether you build or buy one. For a chamber of the dimensions you propose, I'd look for a 10" or 12" throat diameter to keep your pumpdown time in the reasonable range. A turbopump would be even better, and sometimes, deals can be found if you don't mind piecing together a turbo head from one seller and a controller from another. Complete, ready to run package deals are always more expensive than individual parts. The cables are always the hardest part to find, and the connectors often tend to be proprietary. Avoid deals that are listed as "No Returns Allowed", or you may find an expensive boat anchor. Dave On 5/3/2010 1:48 PM, B. wrote:
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