Working Diffusion Pump?

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The Super Nerds Team
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Working Diffusion Pump?

Post by The Super Nerds Team » Sat Jul 14, 2018 9:07 pm

Greetings fusioneers,

We have recently purchased a MetroVac 033C vacuum diffusion pump with the help of a new friend of our's from this forum (Joshua Guertler, another follow Rhode Islander). We bought it at the attached link from EBay:https://www.ebay.com/itm/ONE-1-diffusio ... 1885005563
We are looking to give it a good and thorough before the time to send it back expires.

With the newly received diffusion pump, we would like to respectfully request that the community of this forum look over the pictures taken to see if the pump contains a proper heating unit, water cooling unit, and looks mostly whole and functional. Also, we were wondering what the two brown-yellow vinyl tubes were purposed for and if they may have lead to an important part that has not been included. Also - as a quick thought - was the copper tube on the fifth image the portion that goes to the roughing/mechanical pump or to the desired vacuum chamber? And where would the bottom plug on the pump go to? Thank you.

Sincerely,
The Super Nerds Team

Please see the images in this linked google document: https://docs.google.com/document/d/17KA ... sp=sharing

John Futter
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Re: Working Diffusion Pump?

Post by John Futter » Sun Jul 15, 2018 1:15 am

Okay
you all have not been doing much reading on this site
We prefer that you upload photos resized resampled to 1024x 768 pixels max ( note you are not paying for server space)
the reason we do this is most external links dissappear in time so this entire post becomes meaningless with a magic black hole ending. This of course includes ebay references.

please correct

The Super Nerds Team
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Re: Working Diffusion Pump?

Post by The Super Nerds Team » Sun Jul 15, 2018 2:44 pm

Sure thing, here are the newly updated images and excerpts from the EBay site before the links are gone:

Here is an excerpt from the EBay site:

"ONE (1) diffusion pump MetroVac 033C

0.35 KW Heater 240 Volts

The main flange has an OD of 5.0 inches. The o-ring for this flange is about 3 7/16 inches nominal diameter.
This is the o-ring grove center to center diameter.

The small flange has copper pipe of 9/16 inch diameter. This copper pipe stem is part of a plumbing assembly
which includes a valve----one which connects onto a threaded port, via a nut. The female threaded port that the
nut screws onto is of 1 1/4 inch diameter. For one unit, this pipe~valve assembly extension is missing..
"

We were wondering what the author means when they reference the copper pipe leading to the valve. We assume that this is the section which will lead to the roughing/mechanical pump. We were also wondering if anyone knew what the "pipe-valve assembly extension" was and how it could be replaced.

The following are the selected images:

Image
Attachments
IMG_20180714_132620054_HDR-1024x768.jpg
FUSOR PUMP PICS.jpg

The Super Nerds Team
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Re: Working Diffusion Pump?

Post by The Super Nerds Team » Sun Jul 15, 2018 7:14 pm

Image

Here are the remaining images from the diffusion pump (please read the questions on each image).
Attachments
jullydiffusiontest 5.JPG
Does anyone know which is the oil input and output tube?
julydiffusiontest 3.JPG
julydiffusion test 4.JPG
Does the copper tube go to the roughing pump?
julydiffusiontest 6.JPG
julydiffusion test 7.JPG
What is the top-most plug for?
julydiffusiontest 2.JPG
What is the valve and the central red spot/button for?
julydiffusiontest 1.JPG

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Dennis P Brown
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Re: Working Diffusion Pump?

Post by Dennis P Brown » Mon Jul 16, 2018 12:14 pm

I do not know the policy for groups here (there are, of course) so if that has not already been done, then it should be completed. Richard can address that issue if you don't know what to do.

That is one old diffusion pump. As for your questions I can only give guesses since I am not familiar with that exact unit so here are my ideas to your questions:

I assume those are cooling fluid lines. The input tends to be attached to the fore-line section of the diffusion pump (DP) so the coolest fluid arrives to the unit there. Helps prevent back flow. The fluid output would be for the line on the DP main body. The arrangement is not exactly critical but that tends to be best practice. I have never heard of oil cooling being used but again, not an expert. Most fluid cooled DP's just use water.

The copper tube appears to be the fore-line pumping port.

The "red" dot and electrical line might be an over-temp or fluid pressure sensor. As for the valve, it might control the output line on the DP for the fore pump.

If you decide the valve is useless for your application, appears like that entire assembly can be 'screwed" off.

From past experience by other posters, the top flange of the DP might need a custom adapter to allow the DP to mate with your fusor pump port.

The simplest and only manner to first test the heater is to ohm it for continuity. Then if it both passes and is not 'shorting' to the pump body, it is easy to test - just apply power and see if the metal area near the base starts to warm. Don't allow the unit to over heat as this can burn out the heater element. If it gets very warm to the hand, it is likely working. I would strongly suggest not to use water boiling test. Since you knew the unit was 220 volt then you must have access to that voltage.

The Super Nerds Team
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Re: Working Diffusion Pump?

Post by The Super Nerds Team » Mon Jul 16, 2018 1:41 pm

Greetings Mr. Brown,

Thank you for your response, it has helped us a great deal. We were also wondering if you had an idea of where the oil input for the diffusion pump could be, as it seems to differ pretty greatly from design-to-design. Thank you.

Sincerely,
The Super Nerds Team

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Rich Feldman
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Re: Working Diffusion Pump?

Post by Rich Feldman » Mon Jul 16, 2018 2:27 pm

It's analogous to the water input port for a teakettle.
tk.jpg
Did you think the DP consumes fluid in normal operation? You can learn a lot about them from the Internet without posting questions to people. Maybe you guys can divide up the work. Browse this forum. Search this forum. Read the FAQs. Browse the websites of some DP makers, and download some user's manuals.

If access to a 220 or 240 volt power outlet is inconvenient, consider the ubiquitous 120:240 volt power converters for travelers and expats. Being autotransformers, they are much smaller, lighter, and less expensive than isolating transformers with the same VA rating.

Personally, forum messages signed by "the team" feel sort of anonymous. How 'bout somebody's real name? Nathan Nerd, Corresponding Secretary?
Last edited by Rich Feldman on Mon Jul 16, 2018 2:35 pm, edited 1 time in total.
Richard Feldman

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Dennis P Brown
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Re: Working Diffusion Pump?

Post by Dennis P Brown » Mon Jul 16, 2018 2:34 pm

Putting oil into a diffusion pump (DP) is trivial for most units - one simply pours the REQUIRED amount of DP oil through the main opening (the DP throat. Don't over fill and you need to find out the exact amount for that specific pump.) Also, you may need to clean the inside of the DP first. Acetone, and ethanol alcohol are good and safe solvents to use. Never use water as this isn't easy to remove. The internal jets may or may not be easy to remove. If easy, just remove the jets and clean separately (but do note the order disassembly of the parts!) If not easy to remove, just clean with the jets in place and pour out the dirty solvent. Continue to add, clean and pour out solvent until it shows clear and clean. Warm solvent works better (but never warm solvent with an open flame like a gas stove!! Or a microwave oven!!!)

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