Re: Caring and feeding an Edwards speedivac?


"Nick Mueller" <muellernick@xxxxxx> wrote in message
news:5lvrroFaoiqsU1@xxxxxxxxxxxxxxxxxxxxx
Hi!

A Edwards vacuum pump "speedivac" got a new home. :-)) Thank you
Bob!

Right after checking wether it runs, I checked the oil level and
rushed to a
precision-plus (www.precisionplus.com) dealer near Munich to get a
new fill
of vacuum pump oil. The old one was only three spoonfull of brown
ump. :-)

As I have no manual (and can't find one on Edwards' site), I have to
do some
guesswork.

Air-load: There is a screw (a valve) on top of the pump, that, when
fully
closed, makes the pump sound more like a Diesel. Opening, the sound
is
getting smooth and air (just a bit) is coming out of the outlet.
Fully
opened, the pump makes a boiling sound. I guess this is the
air-load. Do I
have to open it when the chamber I'm evacuating does contain some
media
that is boiling? Thus it doesn't condense in the pump?

Min pressure: The sticker says 1mm Hg with full air-load. This would
translate to 1.3 mbar. I don't get that according to my pressure
gauge. I
do get 30 mbar (gauge is class 1.6) according to the gauge. Now I
connected
a container with some water in it and it does boil (a bit) and the
reading
then is 50 mbar. Water should boil at 20°C and 20 mbar (at about).
So it
looks like the gauge is off by 10 mbar or so.
But I do not get a better vacuum when the air-load is closed (no
container,
just the gauge connected to the suction side) Leaks? Still some
water
(there was) inside the pump? The plate on the pump says "0.02mm Hg"
without
load.
Now should I let run the pump with the inlet closed and the air-load
opened
to get rid of moisture inside? When I unscrew the filler cap for the
oil
while running, fumes are getting out. Hard to say wether water or
oil. I
don't want to open the pump (if it can be avoided) and risk to ruin
gaskets
that will be hard to get.

Oil trap:
Ooops! One time, it looked like the pump spilled some oil (I checked
the
level, it's OK) out of the suction-side. Do I need a trap or new
gaskets? :-)

Varnish-trap:
Does it make sense (I think) to have a trap that could catch some
varnish.
Just in case.

Besides the questions, the varnish I have now is boiling. That
doesn't make
too much sense. I'll phone the dealer and maybe need something
different.
Anyhow, I do have an useless prototype in the oven to see what
happens.

Any thoughts and dos-and-donts welcome!


Nick
PS: And to the spark-coils:
Finally bought an LCR-meter to check what I did. Wasn't too much
off. Also
measured a Bosch spark-coil (black, not a blue "performace coil", an
old
one, that draws 4A) and it has an energy of 50mJ. That's what mine
have
too. Also found a book, that states that 10mJ are enough for model
engines.
More to measure and tune ...
--
The lowcost-DRO:
<http://www.yadro.de>

Amazing pumps those Edwards Speedivacs, though I would have thought
it overkill for varnish impregnation! When I was a "callow youth" two
or three years ago (ok back in the late 1960's) and worked for
Mullards, we had rows of them evacuating sputtering chambers where we
were making indra-red devices for the MOD. A very satisfying gupling
sound they make <G>

AWEM


.

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