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Help with Speedivac F203 Diffusion Pump

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Steve Conner

Tue Nov 30 2010, 05:11PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

IntraWinding wrote ...

Thanks for trying for that paper. Here they ask for an Athens/Institution login , which presumably gets you it without further cost

I tried that using my Athens login, and it didn't work. I'm guessing that the university has the cheaper ScienceDirect membership that only gives access to selected journals, and "Vacuum" isn't one of them.

Proud Mary

Tue Nov 30 2010, 06:25PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

IntraWinding wrote ...

I think they refer to this sort of deposit as 'varnish' since the chemistry is similar to the 'drying' of paint.

Have seen the inside of one of those old carburettors that had a brass float in them? It reminded me of that.

IntraWinding

Tue Dec 07 2010, 08:43PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Ash Small wrote ...

The diagram below should help explain it.

It forms part of the fourth stage, it also containd a foreline baffle, and is water cooled on mine as well.

Are you able to post a photo of yours?

Yes, thanks, I'm sure it's a forline baffle now. No water cooling for it though. I think mine is a rather old design. I'm currently derusting the pump. but I'll try to get some photos tomorrow.

Proud Mary wrote ...

IntraWinding wrote ...

I think they refer to this sort of deposit as 'varnish' since the chemistry is similar to the 'drying' of paint.

Have seen the inside of one of those old carburettors that had a brass float in them? It reminded me of that.

Yes, me too.

IntraWinding

Sat Dec 11 2010, 01:23PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Here's the photo. Click for more detail.

Proud Mary

Sat Dec 11 2010, 01:29PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

So where's the heating element, Alan? In that round box structure at the bottom?

plazmatron

Sat Dec 11 2010, 02:38PM

Registered Member #1134 Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351

Sorry I missed this thread people!

The oil you should use will be DC-704. Neon sign suppliers stock it in small amounts, so it shouldn't break the bank for a 50ml charge.

DC-704 will not "crack" or chemically react , even if you opened the pump up to atmosphere during running (still not recommended though!)
So you are safe there regarding where copper is showing though the plating.

Given the age of the pump, it is likely it used an organic pumping fluid, which has at some point oxidised, hence the varnish deposits. A bit of steel wool and acetone should remove them.

Yep the metal Disk the the bottom of the photo is the heating element.

WRT the Asbestos in the shell, I would use ordinary rock wool as found in loft insulation for that.
Normally anything below the watercooled section should be very hot to the touch during use. The insulated shell prevents you from incinerating stray digits, and helps maintain a steep temperature gradient between the condenser and the boiler.

By the way, you can not use DC-704 or any of the diffusion pump "oils" in a rotary pump.
First off it would be insanely expensive! Secondly these are not oils in the usual sense of the word, they are more accurately working fluids, and will not sufficiently lubricate a mechanical pump. In fact, if a significant quantity of Diffusion pump fluid was to enter the rotary pump, it would ultimately damage it.

A simple 6 inch length of foreline stuffed with a copper scourer or two ("Chore boy" in the US) will actually do quite an amazing job of preventing backstreaming of rotary pump oil.

Les

Ash Small

Sat Dec 11 2010, 05:30PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

IntraWinding wrote ...

. Yes, thanks, I'm sure it's a forline baffle now. No water cooling for it though. I think mine is a rather old design. I'm currently derusting the pump. but I'll try to get some photos tomorrow.

.

Having seen the photo, I'm sure your forline baffle is watercooled. The cooling pipe coils around the foreline baffle, then around the pump body, if I'm not mistaken.

Your pump looks very similar to my two. What is the internal diameter of the body?

Ash Small

Sat Dec 11 2010, 06:38PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I found this while looking for something else:

There is more info here:

and more info on diff pump oils here:

Ash Small

Sat Dec 11 2010, 07:02PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

plazmatron wrote ...

.
By the way, you can not use DC-704 or any of the diffusion pump "oils" in a rotary pump.
First off it would be insanely expensive! Secondly these are not oils in the usual sense of the word, they are more accurately working fluids, and will not sufficiently lubricate a mechanical pump. In fact, if a significant quantity of Diffusion pump fluid was to enter the rotary pump, it would ultimately damage it.

.

The confusion arose here because I'm aware that Fomblin oil can be used in diff pumps and rotary pumps, however, it seems that there are different types of Fomblin, I had only come across one type, Fomblin 14/6 if I remember correctly, while I was working for a company that builds PECVD and similar systems.

EDIT: For more info on Fomblin and Krytox see the previous post.

testtest

Sat Dec 11 2010, 11:24PM

Registered Member #3271 Joined: Mon Oct 04 2010, 02:29AM
Location: Canada
Posts: 159

Proud Mary wrote ...

Steve McConner wrote ...

Everyone likes to think that one of their countrymen invented TV. If you asked me, of course I would say it was John Logie Baird.

1290960937 543 FT0 Mechanical Tv Receiver

1290960966 543 FT0 Mechanical Tv Receiver Photo

Personally, I think some people have invested Farnsworth with the same aura, the same mystique, that has accumulated around Nikola Tesla, both of whom I'ld characterize as interesting but minor inventors working far away from the great scientific debates and discoveries of their times, men with a whiff of the the unrecognised genius myth about them, like the tormented artist in his garret.

I have an old Sparton multiware radio from the WW-II that has a connector in the back labeled "television" Much like your schematic. In the days of mechanical scanning TV with a rotating disk with holes (Nipkow) and reproduced with a synchronous motor from the same power grid. The camera was of the flying spot type with an arc lamp in the studio. Several versions with scanning mirror stacks, belts and such are well documented in old books such as Alfred Ghirardi, "Radio Physics Course" 1933. I can scan a few pages for you should you be interested (copyrights are most likely a non-issue now!). They even had huge rotating slotted disks with colour filters too. Must have made quite a noise in the room...

The breakthrough was electronic TV with the CRT (kinescope) and image disector tube (iconoscope and such) with a photoelectric mosaic plate in comparison to mechanical TV. That was his genial contribution that made TV practical. I have an old TV with electrostatic defection instaed of a electromagnetic yoke deflection while RCA was searching for the best approach for a compact receiver.

My point is not so much who invented TV, several countries will claim it. It was a process enabled by technology as the decades passed. Your kids will likely think TV was invented by the company that marketed the first LCD flat displays, or digital transmission, or the LEDs, or.... you always stand on the shoulders of others.

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