Looking at new vacuum pumps and needing feedback

[David Geer]

What do you all think about this vacuum pump system? (http://www.javac.com.au/shark-vacuum-pump-pr-16140.html)

Ultimate vacuum is 10 microns.
Nominal Capacity: 162 litre/min @ 50hz, 5.7cfm, 9.7m3/hr
Speed: 150 litre/min @ 50hz, 5.3cfm, 9.0m3/hr
Vacuum: < 15 micron (typically 10 micron)
Oil Capacity: 750-800 ml
Dual Stage: configuration, ratio 9:1
Fittings: 1/4 and 3/8 SAE flare
Isolation: 1/4 turn valve automatic no oil suck back
Motor: 0.32 Kw @ 1440 rpm
Weight: 12 kg

The pricetag for me would be a little over $1,000 USD after S&H. The company has others like turbomolecular pumps that can get down to 7.5 x 10^-11 Torr (TURBOVAC and TURBOVAC MAG).

And yes before anyone asks, I prefer higher end equipment. It simply runs better and lasts longer than second hand stuff. Looking at buying 1 piece per month until I have everything needed for my fusor.

[Tyler Christensen]

The thing is, for fusor use that's not really "higher end" (it's advertised 10 microns, so that means you won't really get close to 10 microns with a chamber and hosing attached), you'd be SO much better off with a nice second hand welch belt drive pump, or basically any other nice name brand used pump. And if you're willing to spend $1000, you can get an extremely nice second hand welch belt drive.

Just my opinion on vacuum pumps, basically never buy new.

[David Geer]

Well that's to be used as a backing pump to their turbomelocular pump TURBOVAC MAG with the advertized ultimate pressure of 7.5x10^-11 torr. Also, I should've worded that better. I prefer buying brand new because of reliability/shelf-life issues that arise in secondhand components (I consider higher end by these terms).

[David Geer]

Just took a look at the Welch belt drive vacuums and their specs. They cost way more and perform far worse than the pumps I'm looking at with ultimate pressures nowhere as low, far slower pump down times. Why purchase something that has 3-6x the pricetag and doesn't even come close to the same workload?

For the same price as a Welch belt driven vacuum pump, I can purchase both the backing pump (rotary vane pump) and a turbomolecular pump (w/cash leftover) and get down to near 0 micron pressure in less time.

[Tyler Christensen]

Well, if you're hard set on buying new, I guess this is a good option. The thing is Welch belt drive pumps are practically indestructable under fusor load, and will effectively last forever for our use (far longer than this new pump you linked to will ever last), and even if you buy a welch used and it's decades old (as mine is), it'll still be performing great for many many years to come, probably longer than you're using it.

As far as your pressure comparison, compare backing pump to backing pump, and secondary pump to secondary pump. If you really want to buy a brand new pump that might pull your chamber to 30-40 microns in reasonable time that looks to be of somewhat sketchy construction, feel free, just saying that in general, a welch belt drive pump is probably going to be a better buy in the long run.

In my view you're looking way too literally at the term new versus used, sometimes a 20 year old used product is better than some other brand new product when they both cost the same (aka a used welch versus a new random offbrand HVAC pump)


Note I paid $80 for my welch 1400 and wouldn't dream of trading it for your brand new $1000 pump

[David Geer]

I admit the Aussie company put the damn thing in a plastic casing shaped like a shark but I was looking at specs and not the flashy cover pieces. I did notice the 1402W Welch is "explosion proof" at american voltage standards.

Also, does the Welch setups have the anti-oil leak back capability?

[Tyler Christensen]

Typically you use a vapor trap between the welch and secondary pump (be it a turbo pump or diffusion pump) to limit oil backstreaming, although it's not really all that necessary for fusors, I've never used one and have done just fine.

[chad ramey]

David,

If you do a brief search in the vacuum forum, even just a quick browse, you'll be presented with tens of posts that are seemingly carbon copies of your above post. The question "is this pump good?" is relatively infamous on this forum and we have installed many really nice features such as "search" and "faqs" to the top of each page here on the site to get rid of it. I don't mean to be harsh, but the facts are there, use them. The point of the matter is: there is a huge wealth of information on this site, please take the time to look through it before posting.

-Chad

[David Geer]

Well, I'll keep looking at pumps. I really only wanted feedback on that one and not a sales pitch for another type. From the specs, the one I mentioned in the first post has a good ultimate pressure for a backing pump and then a secondary pump can get the rest of the way to the desired pressures I'm looking for.

[Steven Sesselmann]

David,

Javac is an Australian pump, and will be fine as a roughing pump, it's a two stage rotary pump and it will more or less do what the broshure promises (exept the part that it looks good).

I use an older style Javac pump, and it achieves around 25 micron, after I serviced it and replaced the seals and vanes.

Steven

[Carl Willis]

One thing to note is that I'm certain this 150 lpm rating is not accurate anywhere in the medium vacuum range with the supplied fittings. As in other refrigeration service pumps, the inlet plumbing can be expected to choke the speed pretty seriously as pressures fall out of the viscous range. It would be interesting to see the pump curve, to see what its speed would be like while backing a typical turbopump at <0.1 torr, but I can't find one. Note that its speed at 15 microns is zero (the "ultimate vacuum"), while most scientific vacuum pumps still have about half their rated speed in this range and will bottom out 1-2 orders of magnitude lower. I suspect you'd have a frustrating experience trying to back any but the absolute smallest turbopumped systems with this kind of pump in the as-delivered configuration, though it would undoubtedly be adequate for many hybrid turbo-drag pumps.

I agree with Tyler that I'd much rather spend that $1000 elsewhere.

-Carl

[David Geer]

Well, I wouldn't have any problems changing out the fittings to make it run better. It states on the site that the 150lpm is up to 15microns but can get to about 10micron max. This would indicate the drop-off point would be at approx. 15microns. But I'll keep looking through the forum and the mess of useless replies that pop-up in the search function. Guess I gotta choose my wording better.

I would go for industrial/laboratory grade equipment since I plan to start up my own prototyping shop by 2012. CyberGeer Enterprise "You think it, We make it!"

[John Futter]

David
We used to have q few JAVACs at work we threw them all out and only buy Edwards new now. We do buy leybold and Gallileo second hand off Epay as we can get the service kits for these Gallileo D12 major rebuild kit =183 Euro. These kits make the pump as new.
So buying a pump off Epay for US$100 plus a kit at around US$300 makes for a cheap pump thats way ahead of a JAVAC.
The reason we got rid of the JAVACs is that the anti oil suckback fails regularly and you get a turbo full of oil or worse a diff pump many thousands of $$ of manhours to fix.

[Dan Tibbets]

Rotary pump mileage may vary, though I picked up a very old rotary pump that pumped down a small glass chamber (~ 1 liter) to ~ 5 and even 0 measured microns. I don't know how accurate the gauge was, but it took ~ 14,000 volts or more to light the plasma. Of course with the less than pristine vacuum chamber, once there was a plasma, the pressure quickly climbed to 30-60 microns. This illustrates the point that these roughing pumps may pump down to acceptably low vacuums, but their pumping is so slow in this range, that any little challenge- like out gassing / sputtering from the plasma will overwhelm them. That is were the diffusion or turbomolecular pumps come into their own. They will pump much faster in these low pressure conditions, as well as reaching better vacuums.

Cryogenic pumps also work at liquid nitrogen temperatures.
I have wondered if modest cryogenic 'pumps would work to a limited but useful level. Could a in line chanber with a few baffles, that is chilled to perhaps dry ice temperatures be enough to allow a good rotary pump to keep up?

And, would cat litter*, after heating to degas it, have any benifit?

* Cat litter is sometimes made with ______ (I cannot remember the name) which is a good absorber.


Dan Tibbets

[John Futter]

Dan
The words you are looking for
Activated Alumina ie sorption pump

[David Geer]

To John,

I'll take a look at the Edwards pumps. What I'm trying to setup is a pumping system with a good initial max vacuum pressure then use a turbomolecular pump to keep into the single to low double digit micron range. I've already read up on the plasma outgassing that causes the pressure to "jump" and definitely want to be able to keep up with it.

One issue I found with the search function is that a lot of threads are dealing with flanges/vacuum chambers and not the actual vacuum pumps. Still going through them all but since it's taking forever to sift through the "fluff" posts I had posted my question and have at least gotten some good feedback I can work with.

[John Futter]

David
The Edwards pumps are not cheap -- around aus$ 4K for a RV8 rebuild kits for these are expensive around aus$400 hence my suggestions to the others.
In my opinion you wil want an RV8 or better ie RV12 but there is nothing like the old welch slow running pumps. Parts are cheap and they are bullet proof, but as here in
NZ they are very hard to find and shipping from the US is almost prohibivtive unless you ship by sea freight.
From our latest purchase of Gallileo pumps (5) (thanks Lutz) and stripping a couple of them, these are far superior to Edwards pumps for one they use an internal oil pump to lubricate all running surfaces with high pressure oil --I have not seen any other pump do this --the Edwards and others use slash lubrication

FWIW

[David Geer]

Yeah... some of the Edwards pumps go for 10,800$USD and that is quite a bit outside my price range for right now on singular parts. The problem I have been seeing with a lot of the Welch series pumps is they don't get the pressure range I'm looking for. Sadly, it's looking like I'd HAVE to get one of the expensive ones to do what I want to do. Really don't want to scale back the micron range I want to experiment in.

[Tyler Christensen]

I'm confused by your analysis of welch pressures and saying they're insufficient... I don't think there is any welch model that when in decent condition (perhaps a rebuild kit) will give a worse vacuum than the one you listed in the original post.

Also you keep saying you want to use a secondary turbo pump, so as long as you're below around 75 microns, there isn't much to worry about (hence why I just got a cheap welch 1400 and never rebuilt it, pulls down to 50 microns as backing, good enough for me!)

[David Geer]

I'm going to drop this since you don't seem to read the entirety of the posts. Just missed the entire point of the pressure range I want to get out of the pumps.

[Carl Willis]

At the risk of having my reading skills impugned I suppose, I'll second everything Tyler has been saying in this thread.

At the $1000 price point, one has lots of options for a forepump to back a turbopump. My opinion follows the others expressed here...the most sensible choice would be to buy a pump (or three) on the used market that is actually designed to do the job of roughing a turbopump. The Welch pumps are just one example of such pumps; there are many, many reliable choices. $1000 will buy a fully-rebuilt and warrantied roughing pump that looks like it is new. The alternative of spending the same money on a new high-end refrigeration service pump that's almost guaranteed to result in mediocre performance with a turbo (unless the latter has a drag stage) seems nonsensical. David can make whatever choice he wants, but to any future readers hoping to learn from the discussion, the advice in this thread is solid and comes from people with experience.

-Carl

[lutzhoffman]

Hello:

Just my 2 cents worth.....If I was going to go with a HVAC type of pump, then I would buy the Robinair brand of direct drive pump. Robinair pumps have been proven in scientific applications by several credible home vacuum sites, including belljar.net. A new 2 stage Robinair pump can be had new for just a tad over 1/3 rd of the price of the pump that you are considering. This said I would agree with most of what has already been posted on this thread, and I also, would not trade my home rebuilt Cenco belt drive pump, for any direct drive pump.

I do have one direct drive pump, which is a Varian DS102, it will pull down to an honest 25 microns, and I got it on ebay for about 300 USD. There are also so many quality scientific pumps on ebay, which are a better choice in the end in my opinion.

Just one note on the anti-suckback features that are found on many direct drive pumps: I would not depend on these to always work, which may be part of the reason that dedicated aftermarket devices are offered for this application by Varian and others. Many older style belt drive pumps also do not have the suckback problem to begin with, which is another reason that many folks really like them.

Give it some time, mull things over, and read a lot, and you will be happy in the end : )

[derekm]

Having had a leybold D4a a Edwards RV5, E2M18, Pffiefer UNO and a Ritchie Yellow jacket, I would say the most notable difference between Lab pumps and HVAC is the noise level. The lab pumps are all significantly quieter.
There's a very good reason, when pumping down a Aircon system in an already noisy Plant room, the noise the pump makes is not relavent. Besides the HVAC engineer can go away and read his favourite newpaper. Lab pumps are often run in close proximity to someone trying to concentrate on something.
HVAC pumps specs will probably not even state the noise they emit, whereas lab pumps specs usually do.

[derekm]

look at two pumps
Ritchie HVAC yellow hacket - (operations manual on Mfr website) state noise levels over 70dBA
Edwards RV5 - 48dBA (from website)
22dBA is some difference
THe yellow jacket I have (another ebay purchase) can just about get below 5 microns
but is noisy

[David Geer]

I'll take a look at the yellow jacket. Noise isn't a concern for me since I've worked construction, machining and whatnot. Even though I tried to kill the chatter on this thread, I find it nice that people are still trying to help out with advice.