Restored vacuum pump

Hi all,

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.

Pump as found:

Pump restored: Enjoy,

Chris

PS: Sorry if people are getting duplicate messages from me. BT Internet's news service has been truly dreadful recently. I think they propagate messages by putting them to sea in bottles. They then wait until they find a bottle before they display the message on their own server.

Very nice pictures, although, obviously, they do not show motor rewind and such. Congrats!

i

Thanks. I didn't actually do the rewind myself. There's a guy locally who does rewinds at very reasonable prices (about half the price of a new 1/4 hp motor). I didn't quite trust myself to rewind the motor, so I sent it to him. I can't really take a picture of the inside of the motor, but I can see it through the cooling vents and it looks good as new. Sometime I'd like to try rewinding a less important motor, though.

I did all the work on the pump myself and have plenty of pictures of it. Lots of careful disassembly, cleaning and reassembly with new seals. I'm amazed that there are still several companies supplying full seal kits for this pump; it was out of production by 1970.

Chris

Here's my page on overhaul of such pump:

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.

Kristian Ukkonen.

Nicely poetic rant!!

Nice little project to boot.

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):

could also try Island Scientific: 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 here: 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

Thanks, Roy! I am really going to have to get in touch with BT again and put some pressure on them to fix their news server. The problem is that it is run by another company who won't admit the it sucks, and BT seem unwilling to sack them.

Chris

Chris, what vacuum can this pump pull?

I think the official manufacturer's figure is of the order of 0.0001 torr if everything is working perfectly. But I haven't measured the ultimate vacuum as I don't have a working vacuum gauge. I do have some ancient Penning gauges and a controller I might try fixing sometime, though.

Chris

Try

for some neat vacuum experiments and information, Chris.

Garrett Fulton

1 micron? Nice!

Nice site. Thanks!

Chris