ISO Diffusion Pump Flange

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Erik smith
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ISO Diffusion Pump Flange

Post by Erik smith » Sat Sep 13, 2014 4:06 pm

I have an alcatel diffusion pump that has an ISO flange

The diameter is about 4 5/16"
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The flange thickness is about 1/2"
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The lip is about 1/2"
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Chris Bradleys flange sizes
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From Chris Bradleys flange sizes I think this might be an ISO 80 k but my guess may be wrong. So i ask what type of flange is this?

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Liam David
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Re: ISO Diffusion Pump Flange

Post by Liam David » Sat Sep 13, 2014 4:31 pm

I have a vacuum catalog with the actual flange sizes printed in it. From my measurements, it is an ISO 80.
-Liam David

Erik smith
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Re: ISO Diffusion Pump Flange

Post by Erik smith » Sat Sep 13, 2014 4:48 pm

I am going to purchase a iso-conflat adapter off of Ideal Vacuum products

Image
Image

http://www.pchemlabs.com/product.asp?pid=3829

My diffusion pump flange ISO groove
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Will this adapter work with my diffusion pump? I am concerned about how how the o-ring from the adapter will fit with my diffusion pump flange?
http://www.pchemlabs.com/product.asp?pid=3829

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Dennis P Brown
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Re: ISO Diffusion Pump Flange

Post by Dennis P Brown » Sat Sep 13, 2014 6:23 pm

If I am looking at the flange correctly, the O-ring goes between a two piece flat metal split plate assembly called a centring ring (were each of the two metal rings form one assembly and has a tiny spring holding the unit together.) One of those metal rings has a raised lip that seats into the throat of your DP shown in the picture - the O-ring does not go into any type of grove but sits on/between the two metal plates that are part of the DP and adapter pieces. The adapter you show in the schematic uses "knife edge" seals for copper gaskets and isn't suitable for o-rings nor does your DP appear to use that type of seal but rather, an O-ring in a centring assembly and claw clamps. Unless I am miss-reading the DP, then the one you show in the schematic isn't the correct adapter to use.

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Chris Bradley
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Re: ISO Diffusion Pump Flange

Post by Chris Bradley » Sat Sep 13, 2014 7:06 pm

Looks OK to me - of course those photo/diagram images show a generalised view (in fact, they show the reverse to each other of the ends), whereas yours would be more like a tube with two different endings, one ISO one CF.

You get these clamp things with ISO, you can see one in the photo with the size tables. You can buy as few or as many as you like. 3 is probably best for mechanical stability, though you'll likely get away with two if you are on a tight budget and you find they are 'overpriced'! You don't need to tighten them too much, just nip them up gently, and then nip them gently again once there is a vacuum drawn.

You can even make do with regular bolts and some mudguard washers that you bend at one edge. It is only for mechanical support, the vacuum does the sealing for you.

If you want to go 'cheap' and you find any other sort of 'flat' flange that is around the right size, all you really need to do is cut a flat ring out of sheet rubber and place it between the two parts. Flat flanges are easy to seal that way to 10^-5~^6. Not good enough for scientific vacuums, perhaps, but fine for discharge plasma/fusor stuff.

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