Nick,

?

The sorption pump exploits the ability of certain materials to capture and hold large volumes of gas when taken down to liquid nitrogen temperatures.? You hook it up to your system (depending on the size of the system, you may need more than one “pump!” and immerse it in the LN bath.? You “empty” it again by allowing it to return to room temperature, venting the gas out another valve.

?

It’s a roughing pump, believe it or not!

?

It has traditionally been used in environments where absolutely no hydrocarbon contamination can be tolerated.? I can’t imagine it would make sense for any amateur-built system (LN is megaspensive, and you need lots of it)…

?

-John

?

From: [email protected] <[email protected]> On Behalf Of Nick Andrews via
Sent: Friday, June 17, 2022 4:18 PM
To: [email protected]
Subject: Re: [VacuumX] vacuum chamber advice

?

CAUTION EXTERNAL EMAIL: Do not click links or open attachments unless you recognize the sender and know the content is safe.

?

I also acquired a Huntington Cryo Sorption pump really cheap.? Not sure how they work or if it even works.? Need to research it...

?

On Thu, Jun 16, 2022 at 7:15 PM Dave McGuire <mcguire@...> wrote:

On 6/16/22 11:18, Nick Andrews wrote:
> Hello Dave, funny you mention this...? I finally got my cart (old
> Beckman ultracentrifuge over to TX from NM.? Yeah, it's still on the
> trailer, but I have to clean it off to haul back there at the mighty 4th
> to try and finish my move to San Antonio and sell the house (it's only
> been since Aug 2017 that I started moving).

? ?Ugh, moving sucks!

?

?

I've long said I'd rather be shot than move.? Misery and woe.? We hates it forever!? This one is worse, with 11 years of accumulation, 8 of which was with ready access to a lot of construction demo and university auction winnings.? I moved at least five tons of structural steel here, lathe, milling machine, two dental xray machines, a powder diffraction xray, so, so much high voltage stuff, lasers, boxes and boxes and boxes of books and magazines, Geiger counters and radiation detection stuff.? Not quite like the end scene of Raiders, but I could easily solidly pack a 20' cube.

?

> Super heavy duty cart.?
> Even after I removed the reefer unit and drive motor assembly (bearing
> had failed and leaked oil all over), roughing pump, diff pump, control
> panel/top, top sliding door plate assembly, electronics, the thing still
> weighs over 400#.? I think I am going to try to block off the hole in
> the bottom of the chamber and reassemble it to use as a vacuum chamber.?
> The outer ring has a Hastings type TC gauge in it already.? Probably
> don't need the 1.5" thick explosion shield ring that sits inside that
> but until I need it for something else I think it will be just fine
> where it sits now.? I plan to reinstall the Welch Duo-Seal (1 of 3 I
> have) as the roughing pump or use the Edwards RV one I have, and then
> use a small turbo setup I picked up off ebay (if it works).? Have a
> couple of MKS Loadlock pressure sensors for the system, and a few KF25
> valves.

? ?Very interesting; I don't know much about centrifuges.? They're
mostly used for medical stuff, which I don't get into.? So these big
ones have vacuum systems in them??? I wasn't aware of that.

?

These type are used in lab work all over.? An ultracentrifuge can spin at over 100,000rpm and several people have died from rotor explosions at universities.? Part of why it has that massive steel ring, to contain the shrapnel.? There is a cooling coil around the white inner tub that the refrigeration unit circulated and cooled.? The vacuum is to remove air resistance and decrease heat buildup.? Pretty crazy, right?

?

> I bought (I think) a nice TC gauge with a bunch of tubes at auction from
> Bentley's in Albuquerque along with a ~30L dewar, about fifty 5C collets
> and around 50 slitting saws.? A friend picked them up for me and I plan
> to drive up there from Las Cruces week of the 4th to pick it all up.

? ?Nice!? Take pics!

?

?

I will, assuming he bid on the right lot for me!? It was cheap if not.? Hope the dewar is good, as I need it to transport LN2 to the house to cool my HPGE detector.

?

> Diff pump was assembled to the housing with a flange and o-ring with
> thumb screws which I will need to adapt to the ISO63 (?) flange on the
> turbo.? Was looking at a cross that is ISO/KF63 straight through and a
> couple of KF25 on the side.? But there is no window in the top plate,
> which I'd like to have but might interfere with being able to use the
> slide mechanism to open and close it (assuming I am able to reassemble
> what I took apart before).

? ?Have you seen the pricing on diffusion pump oil lately?? Ugh. :-(

?

?

No, and I probably don't want to!? Aiming to use the little turbo if it all works, but I do have 2 or 3 diff pumps.? I'd like to try building a LN2 generator at some point...

?

> I mostly want a system to pump down tubes for lasers, neon and maybe in
> some crazy time try my hand at vac tubes or nixies.? And eventually
> maybe a fusor.? Still need to test the newer mill, Bridgeport 2J2 but I
> now have a horizontal attachment for it.

? ?Sounds somewhat similar to what I want to do.

?

?

I'll at least have the equipment for it.? Whether I actually get there or not will remain to be seen.

?

> What I've been advised is to go with KF type fittings using centering
> rings and o-rings instead of conflat, as they are reusable versus the
> conflat copper washers.

? ?The single-use washers do seem like a pain, but they're not THAT
expensive if you aren't changing things around a lot.

?

?

Famous last words...

?

? ? ? ? ? ? -Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

Dave,

I dont know what that thing is.??

My suggestion is take a big gulp of air and get your checkbook out and buy this :

Leskers? 1.00 EA? ? ? SKU0323572? ? ?cost? $ 1,700.00 USD

KJLC392-CF-US
KJLC 392 PACKAGE WITH DN35CF-DN40CF FLANGES,
INCLUDING KJLC 392, 2X CONVECTION GAUGES, 10 FT.
INTERCONNECTOR CABLES, AND US POWER SUPPLY

This works.? It will tell you exactly what your chamber pressure is and exactly what your backing pressure is.? You should not turn your turbo on till your chamber pressure is below 2 or 3 torr ( I dont turn mine on till below 1 torr ) and you need a backing pump that can get down to 10 millitorr or better.??

I know it is expensive but Leskers stuff is tough and it stays working.??

Drew?

On Thu, Jun 16, 2022 at 5:35 PM Dave McGuire <mcguire@...> wrote:

? ?Ok, more dumb questions. :)? I have a new ionization gauge tube here
that I would like to use, if possible, in the system I am constructing.
Its connection is a metal tube around 1" in diameter.? I see many on the
market like this, and many with just glass.

? ?How are these generally connected to systems, is there a type of
fitting that somehow attaches to that metal tube?

? ? ? ? ? ? Thanks,
? ? ? ? ? ? -Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

? ?Ok, more dumb questions. :)? I have a new ionization gauge tube here
that I would like to use, if possible, in the system I am constructing.
Its connection is a metal tube around 1" in diameter.? I see many on the
market like this, and many with just glass.

? ?How are these generally connected to systems, is there a type of
fitting that somehow attaches to that metal tube?

? ? ? ? ? ? Thanks,
? ? ? ? ? ? -Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

? ?Ah yes, thanks Drew, I see the difference in that flange.? The second
one I posted last night looks a bit simpler and has an 8" CF on each
end.? It's this one:

? ?

? ?I would probably want to put a blank on one end and use that for the
bottom, and a view port on the top, then plumb the 2.75" CF on the side
down to the pumping system.

? ?What do you think?

? ? ? ? ? ? ? Thanks,
? ? ? ? ? ? ? -Dave

On 6/16/22 11:34, eosraptor1 wrote:
> It looks ok except for that top most interface.? with only 4 bolts
> across what looks to be 6" dia I am not sure that is a "fitting"
> interface.? It may be expecting to be bolted down to a thick plate like
> the top of a cart that holds your vacuum system.
>
> I will look thru my collection of stuff for that flange in case you get
> that thing.
>
> Drew
>
>
>
> On Thu, Jun 16, 2022 at 12:11 AM Dave McGuire <mcguire@...
> <mailto:mcguire@...>> wrote:
>
>
>? ? ? ? ?Hello learned colleagues, I'm hoping to pick your brains for a
>? ? ?little
>? ? ?advice.? I am trying to put together a small vacuum system for basic
>? ? ?experimentation/exploration/education with plasmas of various sorts.? I
>? ? ?have a line on a small molecular drag pump with some accessories,
>? ? ?and am
>? ? ?now looking for a suitable chamber.? I just found this on eBay:
>
>? ? ?
>? ? ?<>
>
>? ? ? ? ?With its various flanges and such, it looks to be flexible
>? ? ?enough for
>? ? ?my very basic needs.? I would, of course, try to talk the seller
>? ? ?down a bit.
>
>? ? ? ? ?However, I am a neophyte when it comes to chambers, fittings,
>? ? ?etc.? I
>? ? ?know just enough to get into trouble.? I see what appears to be at
>? ? ?least
>? ? ?one conflat fitting, etc.? What I'm looking for here is a basic "yes,
>? ? ?that'll do" or "no, don't buy this".? Like "you'll never find something
>? ? ?to fit that flange", etc type of real-world advice.
>
>? ? ? ? ?I'd like to plumb some pumps into it, put in a couple of electrical
>? ? ?feed-throughs, that sort of thing.
>
>? ? ? ? ?Opinions?
>
>? ? ? ? ? ? ? ? ?Thanks,
>? ? ? ? ? ? ? ? ?-Dave
>
>? ? ?--
>? ? ?Dave McGuire, AK4HZ
>? ? ?New Kensington, PA
>
>
>
>
>
>


--
Dave McGuire, AK4HZ
New Kensington, PA