Kristian Ukkonen wrote:

Christopher Tidy wrote:

Just thought I'd post a couple of pictures of the vacuum pump I was
talking about last month. It's a little Edwards ED 35 two stage pump
which I found in a local laboratory's skip (dumpster) last year and
have spent a bit of time restoring. I had the motor rewound, repainted
it, stripped and cleaned the pump and fitted new springs and seals,
and mounted it on some anti-vibration feet. Now it works very sweetly
and holds its vacuum for more that a week after I switch it off. I'm
planning to use it for some experiments on electrical discharges in
low pressure gases. I'm meaning to create a web page with some
pictures of the restoration, but so far I haven't got round to it, so
I thought I'd share a couple of pictures.


Here's my page on overhaul of such pump:
http://www.iki.fi/ktu//es50/es50_overhaul.html

This is the single-stage (ES) version, the double
stage (ED) version has two rotary vane units.
Otherwise very similar - the failing output valve
is identical in both.

These old pumps really last for ever, with
tender loving care from user.

That's a nice page. I plan to do something similar, hopefully including
a bit of history about the firm of W. Edwards, but I haven't got round
to it yet. You're right that the ES 50 is very similar to the ED 35.
Apart from the fact that one's a single stage pump and the other is two
stage, the only difference I can see is that the ED 35 doesn't have the
nipple on the exhaust valve.

Seal kits for these pumps are still available from several firms. I got
mine from Kevin at GE Scientific (now Vacuumplus):
http://www.vacuumplusuk.com/
You could also try Island Scientific:
http://www.island-scientific.co.uk/

After talking to several people at Edwards I acquired a manual for this
series of pumps. It was published before the ES 50 was introduced, but
it still includes a lot of useful advice. I put it online for a friend
who is restoring another Edwards pump. You can download it he
http://www.ruggedmachines.com/docsto...nce_Manual.pdf

I don't know if the ES 50 uses the same shaft seal as the ED 35?
Somewhere I have a spare ED 35 shaft seal, because I ordered one before
I knew that a full seal and spring kit was available, then the kit
included another. If it fits your pump you might as well have it - it
isn't doing me any good right now :-D.

Best wishes,

Chris