Re: vacuum pump on da ebay

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Original poster: Ed Phillips <evp@xxxxxxxxxxx>

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

Also has a 2 stage that's rated .1 micron/millitorr. Always thought a 
diffusion or turbomolecular was needed for that low (almost low 
enough to make your own vacuum tubes/caps/etc).

Mike"

    That, of course, is the seller's number at ZERO pumping 
speed.  A 2-stage pump in halfway decent shape can get down to of the 
order of a micron if the oil is clean.  OK for discharge tubes but 
some sort of diffusion pump is needed if you want to get to a "black" vacuum.

Ed