Re: Fridge compressor for vacuum pump?

To: tesla-at-pupman-dot-com
Subject: Re: Fridge compressor for vacuum pump?
From: Jim Lux <jimlux-at-jpl.nasa.gov> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Thu, 01 Apr 1999 18:28:54 -0700
Approved: twf-at-verinet-dot-com

Tesla List wrote:
> 
> Original Poster: Alex Crow <user-at-alexcrow.clara-dot-net>
> 
> Dear All
> 
> I just managed to rip out a compressor from an old freezer (doing my bit
> for the ozone layer in the process!) and was wondering which bit sucked
> and which blows - the big pipe at the top which went into the freezer or
> the one at the back that went to the radiator? It's also got three mains
> wires, but I haven't opened the junction box yet so maybe I'll work it
> out then.
> 
> Anyone used these as a vacuum pump before? what sort of performance can
> I expect?
> 
> Alex Crow
big tube is in (low pressure), little tube is out (hot, high pressure)
Probably a capacitor between two of the wires, power applied between
two, and possibly a relay or something to switch the cap.
The performance is highly variable in vacuum pump duty. Does the pump
still have the oil in it? In a refrigerator or freezer, it is a nice
closed system, and the relatively cool refrigerant coming from the
evaporator (the cold coil) is also used to cool the motor of the
compressor (cheaper, etc.). When using it as a vacuum pump, you may not
get the same cooling effect. However, since it was free, if you burn it
up, you've got yourself an education, so not all is lost. Don't forget
to tell us what model it was, etc. so others can benefit from your
fortune or mis fortune, as the case may be.