Diffusion pump power wire convert

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Yang Minju
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Diffusion pump power wire convert

Post by Yang Minju » Sun Jun 10, 2018 12:39 pm

Hello.
I found a Edwards Diffstak 63 diffusion pump for my fusor. The pump looks good and the voltage is suitable for me.
But the problem is that the power of this diffusion pump is unknown. As far as I know, Diffstak uses a dedicated power system controller...
Since I can't get a power system controller, I try to convert the wires to fit into a regular house socket. is this possible?

Pump link is here http://itempage3.auction.co.kr/DetailVi ... 15&frm3=V2 (It may be strange because it is Korean web site. Sorry!)

If this is not possible, I'm going to buy a pump on eBay.
https://www.ebay.com/itm/Agilent-Varian ... Swax5YtyYc

This model is AX-65 Diffusion Pump Walnut Creek Version, I found Electrical Connections in the PDF manual.
EC.PNG
Is this also possible?

Thanks!

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Rich Feldman
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Location: Santa Clara County, CA, USA

Re: Diffusion pump power wire convert

Post by Rich Feldman » Sun Jun 10, 2018 6:15 pm

The diffusion pump in Korea looks fine, and even includes a throttle valve.
I don't know anything about special power controllers for it.
If the voltage is OK, as you said, then conversion might be simply changing the plug to fit your wall outlet, or your variac.

The Korean price number means nothing to me.
The ebay price of the alternate pump, USD $785, is ridiculous. I would offer $150, and think very hard if the seller counter-offered it for $200.

Caveat: in my life I have bought one diffusion pump, and never put fluid or electric power into it.
Richard Feldman

MatthewL
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Re: Diffusion pump power wire convert

Post by MatthewL » Sun Jun 10, 2018 8:10 pm

I have the same pump. This pump has the valve pneumatically controlled, which is nice, but won't work for a fusor. Although, it should be pretty simple to convert it to manually controlled. Edward's Vacuum made the pump for either 120 or 225. If you get it, it should be as simple as attaching a new power cord on the terminal right near the heater, and grounding it properly. Depending on what your mains voltage is in Korea, you can either plug it in the wall, or you may need a step down/up transformer to the correct voltage. The information should be right on the label of the pump.

-Matthew

Yang Minju
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Re: Diffusion pump power wire convert

Post by Yang Minju » Mon Jun 11, 2018 12:39 pm

Thank you so much! But does the pump heater use direct current or alternating current? I think I can cut the power wires and attach a normal plug.

Michael Bretti
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Re: Diffusion pump power wire convert

Post by Michael Bretti » Mon Jun 11, 2018 1:52 pm

Diffusion pumps do not need any special controller. They just run directly on 120 or 240 VAC, not DC. You can just connect it directly to a properly sized and rated power chord for the required current/voltage and should be good to go. I also agree that the second pump is grossly overpriced, absolutely do not spend that much on such a small, used diff pump. I agree that $150 is a fair price for a pump such as this.

Here are a couple of datasheets for the Edwards Diffstak 63:
Edwards Diffusion Pumps.pdf
(1.11 MiB) Downloaded 4 times
Edwards Diffstak Vapour Diffusion Pumps.pdf
(2.29 MiB) Downloaded 4 times

Here is a catalog with the datasheet for the Agilent AX-65 as well:
Agilent Varian Diffusion Pumps.pdf
(2.72 MiB) Downloaded 4 times

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Rich Feldman
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Re: Diffusion pump power wire convert

Post by Rich Feldman » Mon Jun 11, 2018 3:54 pm

Heaters, as a rule, heat the same amount on AC or DC. That's why RMS values are used when talking about AC voltage and current, since 19th century. AC makes life easier for switches.
Richard Feldman

Yang Minju
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Re: Diffusion pump power wire convert

Post by Yang Minju » Tue Jun 12, 2018 1:43 pm

Finally, all my questions have been resolved. Thank you all for your reply!

ian_krase
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Re: Diffusion pump power wire convert

Post by ian_krase » Thu Jun 14, 2018 3:50 am

To slightly elaborate on "makes life easier for switches":

Since AC is going around zero volts and zero amps 50-60 times a second, it's much easier to stop an arc.

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