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Re: vacuum pumps
arcstarter
--- In VacuumX@..., "Jerry B. Hillman" <JBHillman@e...>
wrote: I can get a pump on e-bay (Welsh 1402 - rated 10^-4Torr) foraround $200 but The 1402 is a nice pump. Specs available at I have a used 1397 (which is baout x2 larger than the 1402 and twice as heavy also) which after flushing and refilling with Diffoil-20 is able to approach 1 um vacuum. Not bad for a used pump. These types of pumps are rotary vane mechanical pumps, suitable for your roughing and backing pumping needs. shipping is an additional $200 and I need more information. Isthis an oil diffusion pump?No the 1402 is not a diffusion pump. A diffusion pump resembles a tube with a central jet assembly (which reminds me of a coffee percolator. You will need a 1402 or equiv in conjunction with the diffusion pump if you seek the lower vacuums required for evaporation (0.1 - 0.001 um) -Bill |
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Re: pottential explosion with vd pump
In a bit I am going to test prototype #2 oxygen plazma / ion beam source If I don't check back in you are right.
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Ron White
nano_tronics wrote: i may have a clue to what can cause an explosion with a diffusion pump |
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Re: vacuum pumps
You may be able to use the piston pump to rough the tank and get away with a smaller backing pump. I'm guessing?at this. I know the piston pump will not back up a diffusion pump.? Jean-Guy Moreau wrote:
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Re: vacuum pumps
Jerry
Scroll down at the Lester site they do post prices on all but custom products. you can do a lot better than $5000.00 for a 36" setup if you can make the tank and fittings I have a 6" diffusion pump that will pump down a 36" tank and I paid less than $200.00 for it I would recomend a smaller setup at first to work the bugs out. you can always sell the pumps for at least what you paid. Of course none of this is practical but it is fun.
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Ron White
"Jerry B. Hillman" wrote: Hi Ron, |
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Re: pottential explosion with vd pump
Quite right. I had not thought about the possibility of liquid oxygen though LN2 will condense oxygen in a cold finger. One problem, especially with pumping pure oxygen for glow discharge cleaning, is that in the mechanical pump the oxygen is compressed in contact with a hydrocarbon oil possibly giving a diesel-type explosion. It has happened!!! Always use air for glow discharge cleaning!! Don Mattox i may have a clue to what can cause an explosion with a diffusion pump -- ____________________________________ Donald M. Mattox Technical Director Society of Vacuum Coaters 71 Pinon Hill Place NE Albuquerque, NM 87122-1914 Telephone 505/856-7188 FAX 505/856-6716 E-mail donmattox@... WebSite |
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pottential explosion with vd pump
nano_tronics
i may have a clue to what can cause an explosion with a diffusion pump
if a pumping station with a dif pump is using a cheap HC type oil and oil used in the roughfing pump is of a cheap type it can be a hazard on the following condition 1) the above pumping setup used for oxygen plasma experiments or any highly oxydizing compound associated with the setup at the pumping inlet ( with or without accidental system presurization ) 2) cold trap with accidental system presurization may lead to LOX ( liquid oxygen ) formation on the cold trap and if system is not imediatly repumped to remove excess liquid oxygen condensed on the trap witch may drip into the diff pump "or you'll have a big kaboom has a suprize present :( " if all oil are non oxydizing (roughfing or diffion pump) types there should be nothing to worry about i know that most of the people here are more on the vacuum coating subject so no worry there too but o warn everyboby tempted to play with oxydizer and vacuum pumping that this combination may lead them to the hospital or even worst the morgue any comment on this one is welcome |
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Re: vacuum pumps
Gomez
On Jan 11, 2004, at 7:30 AM, Jerry B. Hillman wrote:
Hi Ron,Some companies offer a free price list for asking, but don't post prices on the web site, as their prices change yearly and not being computer nuts, they don't want to change their web site. Just ask them to send you the current price list. I amAre you in a big hurry to do this project? It may be possible to find the equipment and resources you need at auctions (live, not ebay) and surplus property sales, if you are patient. I waited years to find my Veeco setup, but when I did, I got it for $20. All I had to do was add a roughing pump (I already had one, which I had bought years before for $20 from someone who didn't know what it was worth), but someone else who had found a bunch of great pumps at surplus sales, cheap, gave me an even better one to put in it. If you scrounge the parts, and are willing to wait until you find them, and willing to make lots of contacts in your local amateur science community, you might find that it becomes possible to build what you need for much less. If on the other hand, you throw up your hands in disgust and give up, it is a certainty that it will not get built. ............................. I started out with nothing. I still have most of it left. |
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Re: vacuum pumps
Jerry B. Hillman
Hi Ron,
One thing I despise about most commercial sites is that they don't post their prices. I will not even contact a company about a product much less buy it online unless they post their prices online. I guess their attitude is that if you have to ask how much it is, you can't afford it. I am refering to Lesker.com, however the same applies to many companies that have primarily commercial customers. It has become very obvious to me that this project is not economically feasible for personal use. I estimate a cost in excess of $5000 to build a 36" setup. It is probably much higher. Pumps seem to get VERY expensive as they get larger. I appreciate the help I got that made it possible to evaluate this project. Jerry |
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Re: vacuum pumps
Jerry A?backing pump and a diffusion pump is the least expensive way to go. Shop the deals on E-bay you can do better than 200.00 for shipping. The Welch 1402 pump will do fine for a small setup. The size that you were talking about _36 dia will need a much larger backing pump than this one. I have a 24 dia setup 12 high with a 6 CFM backing pump and a 2 diffusion pump. The backing pump takes about 15 minutes to reach 2X10-3. ?Then I start the glow discharge it should look very impressive at this point. I also start up the diffusion pump. It takes 15 minutes for the glow discharge to go out This should be about 1X10-4 I wait another 5 or 10 minutes to start evaporating aluminum. I just set up this tank a few days ago and I havent repaired the gauges yet so I am guessing at the pressure. The point is you may be able to get things going without gauges. ? You will need close to 1X10-6 to coat glass more than a few inches away from the tungsten. My diffusion pump is undersized for this size tank it should pump down in less time than I take. I use Diffoil -20 fluid in the diffusion pump it is $55.00 per gallon from Lester Co. Check out the Lester site they have a lot of info on pumps and stuff. The real expensive diffusion pump oil is for very high vacuum and fast pumping.
If you still want to make the tank from the big propane tank you have after you cut it check for a heat treating company in your area and have it stress relieved this will burn out the tank but the temperature is not high enough to soften or warp ?the steel. The cost for stress relieving steel is about $0.30 per pound. ? Hope this all helps if I have some errors in my info perhaps someone with more experience will correct me and help us both. ? Ron White "Jerry B. Hillman" wrote: Okay, |
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Re: How can I help?
Not to worry, you can still use it. It will work, just not as well
as the stranded stuff. --- In VacuumX@..., RON WHITE <ron_white@s...> wrote: Kevinshould have done more research. batch fashion, with a fair amount of scrap generated during the initialdo it with a lathe and torch if you create the right type of "die".don't know how much of an issue this is for you. |
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vacuum pumps
Jerry B. Hillman
Okay,
Assuming I conquer the chamber design, how many vacuum pumps do I need and what is the actual vacuum measurement I have to attain? Also, what type of gauge do I need? I can't evaluate the feasibility of this project until I figure out what questions I need to ask and get the answers. BTW - A stainless steel tank the size I need costs in excess of $5000 at tanks.com. One of the few places that put their prices online. Most places don't. I can get a pump on e-bay (Welsh 1402 - rated 10^-4Torr) for around $200 but shipping is an additional $200 and I need more information. Is this an oil diffusion pump? They remove oil before shipping. Is this the pump that uses the $500 per pint oil? Would I need an additional pump? Jerry |
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Re: How can I help?
James Lerch
Kevin,
toggle quoted message
Show quoted text
Thanks for the input on stranding tungsten! In all likely hood, I'll just buy some from your company, and save the 0.01" stuff I have for some unknown future project :) Question, If I cut your stranded wire into 2" sections for forming, will it come "un-wound"? I'm interesting in purchasing three 60" pieces at the moment, unfortunately I just re-stocked myself with a bunch of solid wire, but I'm eager to try the stranded! Does your company have a minimum order? How should we proceed from here? Take Care, James Lerch (My telescope construction,testing, and coating site) "Anything that can happen, will happen" -Stephen Pollock from: "Particle Physics for Non-Physicists: A Tour of the Microcosmos" " Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. " Calvin Coolidge ----- Original Message -----
From: "toglman" <inky@...> To: <VacuumX@...> Sent: Thursday, January 08, 2004 16:03 Subject: [VacuumX] Re: How can I help? Thanks. |
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Re: How can I help?
Kevin
Welcome!
Timing is everything I just bought 30 feet of solid tungsten, --should have done more research.
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Ron
toglman wrote: Thanks. |
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Re: vacuum chamber
Ken and all Hate to be a pest but I have a bit of working knowledge of steel. The water you see on the surface of the steel when you heat it is?a by product of the combustion process and not from the steel. Stainless steel is smoother and corrodes less so there is less surface area to hold water vapor. Add in a little rust and the advantages of stainless goes up even more. But for the moderate vacuum that most of us are able to accomplish without $500.00 a pint oil carbon steel is fine. ? Im hoping to chrome coat my tank soon. ? Regards Ron White Ken Hunter wrote: tank. Heat speeds the process (ever notice how a piece of cold metal |
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Re: vacuum chamber
Jerry I have made a tank from an old 21" dia water tank. I ?cut it just above the bottom dome. Welding the 2 flanges on and keeping them flat?could be a challenge as well as an o-ring seal. ? As an alternative you can get a flat base plate- 3/8" thick will work but it will oil can. I have a 24" with a 1/4" base plate, it oil cans over 1/4" when pumped down but holds vacuum OK.? I'll try to detail the construction. If it is to confusing let me know and I'll draw up a sketch and photos. ? The tank wall is 12 ga .090 cold rolled steel 12" high. The bottom (welded end is 1/4" thick 24" dia flat hot roll steel plate. the top cover is 1/4" thick flat steel 25" dia (actually octagon) ? For the O-ring I welded a x cold rolled steel bar around the cylinder wall 3/16 down from the end. Over this I welded a strip of 12 ga X 7/8? even with the 12ga cylinder wall. ? This forms a nice wide x 3/16 deep channel to hold a o-ring both pieces were only welded to the cylinder wall and not in the channel. ? I would have made the tank a bit larger in dia but I happened to find the 24 disk all cut to size and couldnt resist the time savings. All of the material was free scrap. ? This has worked well and was very easy to fabricate without any machining, I gave up on the water tank because it took to long to pump it down with my small rough pump. ? Making a pump from an old gas engine may not get the vacuum low enough for a diffusion pump to work. I Dont know exactly what the diffusion pump requires but I think it is in the low micron range. Used AC service pumps are available for a few hundred dollars and are easy to rebuild. ? Ron White jbhillman2004 wrote:Okay, so since Ken invited me to join, I'll start asking questions. I |
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Re: vacuum chamber
Jerry B. Hillman
Hi Ken,
I have looked at James Lerch's setup. Actually some time ago on his web site. He used a new propane tank. Very small. I am intending to design my system with the elements beneath the mirror. Still have to figure out how to suspend the mirror upside down, and rotate it too. Jerry |
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Re: vacuum chamber
Jerry B. Hillman
Hans,
I wouldn't heat the entire tank. I would cut the ends off first then heat the ends. I have probably six or seven tons of wood in a burn pile on my property. This pile is 9 feet high and 20 feet across. When I light that, the resulting fire will be hot enough to vaporize aluminum on contact, melt glass, and probably do a number on steel. I haven't looked up the melting point of steel, but I have vaporized an aluminum hubcap, and melted beer bottles in earlier fires. Wood from clearing 10 acres of timber. I just thought that heating up the tank ends would eliminate the propane hydrocarbons and any other absorbed impurities.Rapid cooling is as simple as using my tractor and a chain to drag it out of the fire directly into the pond. Kinda hard on the fish though. Actually, the pond has no fish in it. It only has water in it during wet weather. Jerry |
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Re: vacuum chamber
Ken Hunter
--- In VacuumX@..., "Jerry B. Hillman" <JBHillman@e...>
wrote: Okay,due to absorbed hydrocarbons, or I have to find a way to remove saidhydrocarbons. Jerry... Look at the photo on the Main Page for this Group. What you will see is a chamber made from a Propane tank. Yes, it can be done. There are several ways to remove the adsorbed gasses and it will be required each time you pump down the tank. However I must say that the first time you pump it down will take a lot longer to get rid of the impurities. Once you pump down the tank and let it sit, the junk in the steel will be released and enter the tank. Heat speeds the process (ever notice how a piece of cold metal gets wet when you hit it with a torch?) anyway, each time you pump the tank down it will release some of the adsorbed gasses, water vapor etc. Steel is not the best material for a High Vacuum system as it likes to adsorb water vapor and form rust which then releases back into the tank under vacuum and acts exactly like a slow leak... it'll drive you crazy if you are looking for a "Perfect Vacuum" but if you are looking to get a reasonable vacuum and your pumping station can handle those virtual "leaks" you can get the pressure down to the range where good coatings are possible. Even with your propane tank. I don't think you would need to heat the tank nearly as much as you suggested... hot enough for it to develope a good sweat would be good enough but then you need pump away the released gasses and figure a way to keep it dry somehow to keep it from adsorbing more gasses. Best way is to keep it under a vacuum all the time except when you want to access the interior of the tank. You might consider making your tank similar to James Lerch's in that main page photo. (I prefer to have the mirror suspended and the filaments below the mirror) but he has a good idea about the way to seal the tank and make it easy to take apart for changing the glass. I have an old Stainless Steel tank (36 inch diameter) that already has flanges on it and I don't relish taking 2 dozen bolts and a gasket apart each time I want to get inside it. I will do something similar to James's tank sealing method when I get around to that project again. Ken Hunter |
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