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Vac Pumps

G’day, this is mainly intended for Nina, only I haven’t got her
address. But here’s my long nose again; I have seen
several threads containing requests for vacuum pumps, to be used
for investment, casting, etc. My simple suggestion is, providing
you have a mains water supply with a good pressure, that you at
least think about the vacuum pumps that every laboratory has,
known in the trade as Buchner pumps or filter pumps, used for
vacuum assisted filtration, distillation, etc., in just about
every laboratory in the world, and available from any supplier of
lab equipment at a very low cost - certainly no more than
$15-$20. They are simple gadgets with no working parts, can be
made in plastics, metal or glass - as the original ones were. (In
fact had to make six glass Buchner pumps for a lab technician’s
exam over 50 years ago) They work by a small jet of water
entering a tube slightly larger than the jet, and the jet carries
air with it to cause a vacuum.(Venturi system) Properly designed
and made, this type of pump can produce a vacuum down to 3cms of
mercury pressure which is quite low. Admittedly, the rate isn’t
fast, but a suitable vessel can be evacuated and attached to
one’s system and a valve opened to it suddenly. BUT NOT A GLASS
BOTTLE!! I’ve used such pumps for all kinds of things until I
came to live in a place where we use rain water (off the roof)
stored in an underground tank, so the pressure is very low! I
have to use an old converted refrigeration (ex rubbish tip) pump
now for lab work.

   / /    John Burgess, 
  / /
 / //\    @John_Burgess2
/ / \ \

/ (___)