Strange Feedthrough Flange

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Tidbit77
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Strange Feedthrough Flange

Post by Tidbit77 » Mon May 03, 2010 6:52 pm

I recently acquired a HV feedthrough from Ebay (pictured below), however I cannot identify the flange that it has been welded to. It appears to be an ASA flange, however ASA flanges do not seem to be manufactured in such a small size. Please help me identify this flange.

Will Jack
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John Futter
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Re: Strange Feedthrough Flange

Post by John Futter » Mon May 03, 2010 7:15 pm

Looks like a custom flange

the rest is a 30kV nominal feedthrough should go to 50kV in dry air

myID
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Re: Strange Feedthrough Flange

Post by myID » Mon May 03, 2010 7:50 pm

Hi-

I have a similar feedthrough- with a square flange instead. Just turned a fitting hole in an ISO flange and mounted the feedthrough on the flange- et voila.

Hope this helps
Roman

Wilfried Heil
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Re: Strange Feedthrough Flange

Post by Wilfried Heil » Mon May 03, 2010 8:14 pm

That's a 3.00" OD ASA flange, from the steampipe era. One flange has a groove for an o-ring, like your connector, and the counterpart is just a flat plate.
http://www.edwards.co.il/catalog/13/130107.pdf

Tidbit77
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Re: Strange Feedthrough Flange

Post by Tidbit77 » Mon May 03, 2010 8:35 pm

Wilfried, please correct me if I am wrong but I thought that ASA flange sizes were determined by the inner diameter of the flange, meaning that this would be a 1.5" ASA flange with a 2.75" outer diameter, and I cannot find any of these flanges.

Will Jack

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Doug Coulter
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Re: Strange Feedthrough Flange

Post by Doug Coulter » Mon May 03, 2010 8:59 pm

They were rare even when ASA was more popular (most steam lines were a lot bigger), but they work fine if you can tolerate viton in your system. We've used a bunch of these kind of oddball things with no problem -- like the above, it just mates to a flat plate (which has to be shiny where the O ring mates).
You may need to polish the mating surface to get it to mate leak free. You won't find its mate, I suspect, ever. But they are so simple to make, why even look?

Hint -- we've even had luck bolting things like this to the same sized CF flange if the O ring lands in the flat inner part of the CF (eg skip the knife edge and don't put a copper gasket in there). The bolts even line up fairly well. Since that part of a CF tends to be rough finish, you have to do some polish work with a dremel and buffing compound to make it seal well. With O rings, some waviness can be tolerated, but short-scale roughness will leak so it has to be shiny, even if it has a bit of fun-house mirror effect. Eg the viton can conform to a large scale warp, but not fill in tiny voids.
Why guess when you can know? Measure!

Wilfried Heil
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Re: Strange Feedthrough Flange

Post by Wilfried Heil » Mon May 03, 2010 9:24 pm

The smallest ASA parts which I find now have an OD of 4.25" and various IDs from 0.50" up. You may have to make your own adapter flange, which should not be difficult to do.

Tidbit77
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Re: Strange Feedthrough Flange

Post by Tidbit77 » Mon May 03, 2010 9:29 pm

Thanks for the replies, I think I'll just make my own, I'm assuming .5" 304 SS will be sufficient?

Will Jack

Wilfried Heil
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Re: Strange Feedthrough Flange

Post by Wilfried Heil » Mon May 03, 2010 11:03 pm

Sure, 1/2" steel should be enough to squeeze down a viton gasket without bending. The flange that you have looks a bit thicker, like 3/4", so you just might make the other part with a similar thickness.

I have this same feedthrough with a CF flange, running at up to 50 kV with no problems.

lutzhoffman
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Re: Strange Feedthrough Flange

Post by lutzhoffman » Mon May 10, 2010 7:15 pm

For more options maybe see if the o-ring lines up with a KF-50 flange surface, then if it does, you may be able to use a bulkhead KF-50 style split clamp, which is available on ebay to mate it to a KF-50 weld stub etc.

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