Edwards 2SC20A doc wanted

[rydel]

Hi,

I am on the way to buy an Edwards 2SC20A pump. I can imagine that I am not the first to do that on the list...

I sent an email to Edwards England and they sent me immediatly what they had, I mean the second part of the doc : "Rotary vanes & Rotary piston pumps".

I am in search of the first part. I presume that this model is very old and come from the 1950-60 era. I would like to know what kind of oil I can put inside too.

Thanks in advance.

[Dennis P Brown]

Common diffusion pump oil should work in the DP and I can't see why standard vacuum pump oil shouldn't work in the mechanical pump. One thing for sure, really doesn't matter since you will not find 1950/60's type/grade pump oil on the market today!

The mechanical pump is a design I've never seen and I go back - that said, it could be a simple (single stage) rotor with a dual vane (mechanical) seal (units I saw/used in the early 70's). Should work ok for rough vacuum if not rusted up and that type of old style rotor doesn't need seals (IF it is that type.)

The DP and MP need to be connected and I don't see in the pic how that is done. The valve system (on the gray line) should handle roughing (a chamber) and isolating the DP. Appears that the grey line with two valves 'should' have the mechanical pump attached to it via the common "access tube' that appears between the two valves by using a vacuum hose to ...? ... on the MP.

One thing I noticed is that you will want the cold water entering the green tube at the top of the system (in the picture you have the unit laying on its side with the top of the unit facing the viewer.)

Is the unit for the English or American market? English use 50 Hz (if I remember correctly or is that just mainland Europe?)and American, of course, is 60 Hz. So the motor should say, if not, that could be an issue.
Others may know exactly - I'm guessing.

[Jerry Biehler]

Liiks like a nice setup. Standard rotary pump oil in the mechanical and DP oil in the DP. Nothing special.

Yes, the mechanical pump connects between the two small valves. Those two combined with the butterfly valve on the DP completely isolate it. From the looks of the gooseneck it was hung underneath a table with the baseplate for a bell jar permanently mounted on the top.

50/60 hz really does not matter a lot on motors. The will run faster on 60Hz but thats about it. I have ran a lot of motors from Japan that were 50Hz, 100v or 200v on 120 and 240v 60Hz and have never had a problem. The higher frequency limits the current draw on the motor.

[rydel]

As said in the document,

2S means for the number of stage in the pump, here two
C means gas ballast facility
20 approximate numer of liter/mn at normal speed of rotation
A means quiet running pumps

My questions are :

1) What oil (Brand nime and ref) can I put in it ?
2) Does somebody have the first part of the doc ?

Living in France, voltage is not an issue, 230V & 50hz are OK.

[Dennis P Brown]

Nice to know about the 50/60 Hz! Thanks!

[John Futter]

Rydel
Edwards backing pump oil -OK
Shell Tellus 32
or any other oil that meets the specs ---vapour pressure being the most important
your local oil supplier should be able to cross reference the Shell oil to their nearest or better equivalent.

Tellus oils are non foaming hydraulic oils

[fizz]

We have the original care & maintenance manual for Rotary Pumps here, its about 30mm thick with all parts listing and exploded views.

Part one is only for combined rotary compressors, these only give around the 10mbar range and a small pressure of around 10 psi when in good order.

So may well not be any help regarding what you are showing in your photo.

What do you require that Part 2 does not tell you ? if we can help we will.

If you look on our web site www.recalvac.co.uk you will see we repair and service all the old Edwards pumps etc.

[rydel]

First thanks to all of you for your !

Some questions :

1) Does somebody have the caracteristics of the diffusion pumpe ?
2) Are Inland 19 ou Inland TW ok for the primary pumpe ?
3) Are Invoil 20 or 30 ok for the diffusion pumpe ? What quantitie is ok ?
They are delivered in one liter bottels, the ISO 32 kind of oil is delivered in 4-5 liters.
The cost of the Invoil & Inland is lower. And there are the Diffoil-20 good for the two pumpes !
4) I presumme that I have to put the good temperature to warm oil up to boiling .
May I presumme 130-140° will be ok ? Is there a thermostat for that ?

Thanks in advance.

Charles

[John Futter]

Rydel
attached data sheet from shell for a better oil than I put forward before.

You should also consider using Dow Corning 704 silicon fluid for the diff pump. It is very hard to damage and will stand a few air admittance incidents while it is hot. The Diffoil will turn into a nasty black mess in a single air admittance incident.

There are chinese equivalents to DC704 that are a factor of 10 cheaper

Notice in the attached sheet the vapour pressure of the Shell oil at differing temps

[rydel]

The Shell oil is hard to find. Have you got an idea about the cost at least compared ?