One unnamed diffusion pump.

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Jeremy Sims
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Joined: Mon Jan 19, 2015 4:54 pm
Real name: Jeremy Sims
Location: Southern Ohio

One unnamed diffusion pump.

Post by Jeremy Sims »

IMG_20150210_174728.jpg
IMG_20150210_174751.jpg
Bottom of baffle
Bottom of baffle
Christmas tree
Christmas tree
Top of baffle
Top of baffle
Bottom with cover off.
Bottom with cover off.
My routine on my days off is to immediately after waking up, scour eBay to see if anything new that I may be able afford has been posted for sale. So about 4 days ago this diffusion pump pops up newly posted. $85 Buy It Now. Having recently lost a bid for a cheap turbo I jumped on it immediately without bothering to ask questions. ID of pump is @3" It came with two kf clamps, that huge box on top which I'm assuming is a baffle, and a small unmarked bottle of oil. I was hoping that the Christmas tree would be intact since the baffle was bolted in place and it was. The baffle? has a tube that runs all the way through. It is seriously pitted on the bottom but the area that contacts the O-ring is clear. The power cord! Wow what a wreck. That will definitely need replaced. Have not tested the element yet. What are the two ports with copper fittings next to each other on the bottom? Will set to work cleaning as per the FAQ. No markings on outside to denote a manufacturer or how much oil, specs. Any advice is appreciated.
Doug Browning
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Real name: Doug Browning

Re: One unnamed diffusion pump.

Post by Doug Browning »

That's a Varian HS-2 or NRC 0160 (same thing, Varian bought up NRC)
The water cooled baffle up top is not one of the standard Varian units, could be a custom machine shop design.

Looks like it was a rebuilt one, probably by Idealvac. The Varian is normally olive green color. The two fittings on the side were for a quick cool loop, where water could be run through a loop around the heater on the bottom to cool it down quickly. Used when a gate valve is not available to seal it in vacuum during cool down. The loop was copper tubing, which corrodes out quickly with the hi temp. Looks like the rebuild did not replace it. Not an essential item, but you will probably want to get some kind of valve(s) to shut the inlet and foreline when opening the main vacuum chamber, so you don't have to wait for it to cool down every time. The cold cap on the top of the Xmas tree stack has a big hole where a "Teflon" bushing fits, between it and the stack. Looks like it might be down in the pump from one of your pictures. This is a quite nice diff pump to have, it is fractionating, 285 L/sec, 3 stage plus ejector stage, a stainless steel stack in most models. The one issue that can come up with this model is if the heater has failed, and the last heater cartridge was replaced without putting a MgO (Philips Milk of Magnesia) coating on its surface to prevent corrosion seizure into the platen block around it. One can purchase a replacement platen if necessary but they are pricey from the usual vacuum supply houses. Easy to make one at a machine shop though.

Specs and manual here:
http://www.idealvac.com/product.asp?pid=2779
Last edited by Doug Browning on Tue Feb 10, 2015 8:41 pm, edited 1 time in total.
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Richard Hull
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Re: One unnamed diffusion pump.

Post by Richard Hull »

I'll second that good score. Except for the water cooling, and hopefully a good heater, you got a great deal there. Good luck. Power cord are always loused up on 90% of the diff pumps. Easily replaced.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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