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Re: vac pumps



Original poster: "Kristian Ukkonen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <kristian.ukkonen-at-iki.fi>


Sorry, but the descriptions below are somewhat flawed.

A good (for example, rotary vane) fore pump (mechanical pump) will 
pump down to about 1 mTorr. 

A normal refrigerator compressor will pump down to around dozens of 
Torr, perhaps to 25 Torr.  That is a piston pump.

A diffusion pump will pump decades lower, < 1e-5 torr. Still, there
is (relatively) LOTS of stuff left at 1e-5 or 1e-10, when one looks
at the number of molecules hitting each mm2 of the vacuum vessel walls. 

  Kristian Ukkonen.

btw: The Sterling-Sihi homepage : 
http://www.sterlingfluidsystems-dot-com/
Based on quick browse, you propably have liquid-ring pump..
NOT a good choise for a vacuum pump for most applications.
But ask for a manual from the company..

Tesla list wrote:
> 
> Original poster: "Mike by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<arcsnsparks-at-parlorcity-dot-com>
> 
> Sounds like a "roughing pump" which is used to pump out most of the air from
> a system before an oil or mercury diffusion pump is used to remove the last
> bit. . yes they are useful and I'm sure you can sell all of them you can get
> on Ebay
> 
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Tuesday, April 09, 2002 10:29 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: vac pumps
> 
> Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <bigfoo39-at-telocity-dot-com>
> 
> Tesla list wrote:
> 
> >Original poster: "marc metlicka by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>
> >
> >Hello All,
> >I have access to several "sterling SIHI" VACUUM PUMPS. fROM WHAT I
> >GATHER, THEY USE A FLUID PUMPED THROUGH THE SYSTEM IN ORDER TO CREATE
> >THE VACUUM?
> > Product statements for the model lema 40 is 25 torr.
> >Is any coilers familier with this type of unit? should i keep two for a
> >"great" vacuum sytem?
> >Thank you,
> >Marc M.
> >
> >
> >
> >
> >
> Hi Marc...
> 
> 25 torr is pretty low as far as a diecent vacuum goes...
> the systems sound like they might be the rotory vane type
> 
> there is the oil diffusion type but they can go as low as "milli torr"
> 
> I'll bet if you put one on Ebay it will sell for nearly 100$
> 
> I'd keep at least 2 for myself if I had several in my posession ;)
> 
> Scot D