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Re: metal diffusion pumps

> Roger,
> 
> Ah, a stainless metal pumper. With a wee bit of engineering you'll be on
> your way. Is it air, or water cooled?
> 
> First, find ANYTHING that matches the flange on the pump input. In my case
> the (ancient) pump came with a bolt-on O-ring sealed heavy steel pipe. I
> chopped this pipe down to about 3" tall and fitted a 1/4"-steel cap to it. I
> then cut a hole in the side of the pipe and fitted a NW-KF 25mm flange stub
> to it (available at most high-vac suppliers like Duniway, HPS, etc.). By
> "fitted" I just mean that I cut the parts to size -- I then brought them to
> a SKILLED welder (in my case a retired NASA dude with his t.i.g. rig in the
> garage) and had him do the welding. Couple hours of my time and $25 for the
> welding....

I'd like to add some info about connecting metal components to glass.

Like Ted said, once you get to a KF fitting, you can use one of Eurocom's 
glass "KF" flanges.  You can also use a standard ball-O-Ring joint to 
match a KF metal flange.  These joints are available in about 10 sizes 
and have a flat flange with a groove for an o-ring.  The o-ring is 
usually included with the joint, and they are very reasonably priced at 
about 5-20 dollars depending on the size.  I have a size "15" ball-O-ring 
joint mated up to the KF16 metal flange on my Edwards capsule filling gauge.

The pertinax clamp is just 2 pieces of plastic with 3 wing-nuts and 
screws.  If you have a scroll saw, you can easily make these any size you 
want with about 30 minutes of time.  Since they cost 40+ dollars each, I 
consider it worthwhile.

As to connecting to one of the larger flanges, like an LF/ISO/CF - you 
can get an adaptor to a KF 25 for most sizes.  You can also buy glass 
flanges, with or without an o-ring (and groove) that mate up to your 
metal. Again, you'll probably want to make a clamp out of _plastic_, so 
you don't crack the glass when you wrench it down.  This is how eurocom's 
big system connects to their turbomolecular pump.

I have also seen compression fittings for some of the large flanges that 
convert an LF to a 25mm tube (which can be glass).  This may be a more 
direct route. Duniway has _some_ of these. Edward's, MKS, etc have more.

As to metal systems in general - I am becomming quite fond of them.  I
recently saw some of Motorolla's semiconductor fab. equipment here in
Austin.  They use metal KF stuff for just about everything.  I sure like
those bellows-sealed metal valves.  Really made for a production
environment. Infinitely rebuildable and repairable.  My next manifold will
be such I think. 

    -John Anderson
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