High Powered Rotary Vacuum Pump

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
Blake Resnick
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High Powered Rotary Vacuum Pump

Post by Blake Resnick » Fri Jun 27, 2014 4:06 am

Hello,
I am currently in the market for a powerful vacuum pump. How does this one on ebay look? Does the price seem inline with the others of its class? Also, would I be able to just use some reinforced tubing to attach it to the vacuum chamber, or does this pump warrant something else?
Link: http://www.ebay.com/itm/Alcatel-Adixen- ... 35d865c89a
Thanks,
-Blake

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Bob Reite
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Re: High Powered Rotary Vacuum Pump

Post by Bob Reite » Fri Jun 27, 2014 4:33 am

You would still need a diffusion pump or turbo pump to get down to the pressures required. IMHO You might be able to find a better price for your backing pump.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.

Blake Resnick
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Re: High Powered Rotary Vacuum Pump

Post by Blake Resnick » Fri Jun 27, 2014 4:42 am

This pump would be used for a demo fusor, not a neutron producing one. Therefore, it would pull a vacuum sufficiently deep.

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Scott Moroch
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Re: High Powered Rotary Vacuum Pump

Post by Scott Moroch » Fri Jun 27, 2014 5:14 am

To be honest you can probably find a pump for far cheaper that will suit your needs for a demo fusor. That is a lot of money to spend on only the pump. Keep in mind all of the other components that you will need to buy.

Best of luck,

Scott Moroch
"In the middle of difficulty lies opportunity"
-Albert Einstein

Jerry Biehler
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Re: High Powered Rotary Vacuum Pump

Post by Jerry Biehler » Fri Jun 27, 2014 6:57 am

Nice pump but I would not pay that much for one. You should be able to get it for half that.

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Richard Hull
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Re: High Powered Rotary Vacuum Pump

Post by Richard Hull » Fri Jun 27, 2014 3:23 pm

The owner quotes the corporate specs. It runs fine, he says. Many pumps run just fine that are bad at pulling a rated vacuum.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Blake Resnick
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Re: High Powered Rotary Vacuum Pump

Post by Blake Resnick » Fri Jun 27, 2014 7:06 pm

These pictures are of the plasma currently being formed at 28 inhg. As you can see the results are less than favorable... The chamber itself does not seem to be leaking, despite my scrutiny. So, I attribute the reactors poor vacuum performance to the cheap Harbor freight pump I am running. Is it likely this pump is running so far from its specified max vacuum? Could the chamber be leaking in a way that would be difficult to detect?
IMG_4795.JPG
IMG_4793.JPG
IMG_4791.JPG
Thanks,
-Blake

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Rich Feldman
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Re: High Powered Rotary Vacuum Pump

Post by Rich Feldman » Fri Jun 27, 2014 9:28 pm

I bet you have a gross leak, not a bad pump.
[edit] And the pumping speed is limited by that thin hose of yours.
In the presence of a significant leak, the deluxe industrial pump
would perform no better than your Harbor Freight special. [\edit]

Make sure any gas ballast valve on the pump is closed.
Then when the pump is running, and chamber is pumped down,
there should not be any air flowing from the pump exhaust port.
(try plugging it with your finger).

You know the meaningful pressure must be measured up from zero, not down from atmosphere.
Lacking an absolute pressure gauge, you can use the plasma appearance to judge the gas pressure in chamber.

While the pump is running,
get a small brush and try applying a little vacuum pump oil to the outside of each joint:
- ends of cylinder
- HV feedthrough
- Vacuum gauge port
- Vacuum hose port and all hose connections

If you see any oil sucked in then you have found a leak.
Smaller leaks will be temporarily plugged by the oil, and the pressure will drop.
Plasma appearance and/or the sound of the pump may change.
It will react faster if you use a shorter or wider hose.
Good luck!

[edit] You could also install a valve between pump and chamber.
With chamber evacuated, close the valve.
How soon does the vacuum gauge move, or the plasma change?
All models are wrong; some models are useful. -- George Box

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Chris Bradley
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Re: High Powered Rotary Vacuum Pump

Post by Chris Bradley » Sat Jun 28, 2014 8:50 am

Why buy another pump when what you need is a micron capable pressure gauge to diagnose your existing set-up?

It's pretty mad asking about buying an expensive pump when you don't seem to even have a suitable pressure gauge.

It's also not very good asking after ebay items into the main forum, because it will be a dead link in a month. Put it in trading post, plz.

Blake Resnick
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Re: High Powered Rotary Vacuum Pump

Post by Blake Resnick » Sun Jun 29, 2014 8:24 pm

All of your advice was hugely beneficial! I evacuated the chamber and found several large leaks. I also created a valve to stop the pump from leaking after its deactivation. Now, the chamber holds its vacuum for about 6 hours before returning to normal atmospheric pressure. Also, thank you for your advice regarding a more suitable gauge. How do these two look?

Links: http://www.amazon.com/Supco-VG64-Digita ... cuum+gauge
http://www.amazon.com/Yellow-Jacket-690 ... cuum+gauge

What do you think about the plasmas forming now? Also, do you have any idea what the bright white spot on the copper grid is?
IMG_1780.JPG
IMG_1766.JPG
IMG_1773.JPG
Thanks,
-Blake

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