Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

Any ideas ?

bruno

In article .com, bschwand
says...

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

You need to define what pressure you need to achieve.

10e-3 torr?

10e-6 torr?

10e-12 torr?

Once you define a desired pressure range, that will
deterrmine the kinds of vacuum feedthroughs you will
pick.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

bschwand wrote:
Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

As Jim R. said, you have to specify the pressures
and voltages you want to work at. That said, if
I were building such a thing for a company, I'd
call up Deutsch, tell them what I wanted to do,
then send them a big check:

http://www.deutschecd.com/

They've been solving this sort of problem for many
years.

bschwand wrote:

Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

Depends on what you mean by heat resistant.
Torr-seal works to 120 deg C and 10-9 torr.

http://shop.store.yahoo.com/vacuumshopper/toseeqb9.html

I've heard of people using spark plugs as
feedthroughs. I doubt they'd be any good
at high vacuum though.

In article .com,
"bschwand" wrote:

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

Pretty standard chamber, electrical feedthroughs included. I worked in
labs where we ran 12-20 lines of coax from various plasma experiments in
similar chambers.

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

feedthroughs are standard parts in the vacuum biz. They have special
glass, metal and/or ceramics to deal with the expansion issue. I think
the shop a few miles away is ceramaseal (one of many locations for that
brand), there are many others. On the crude DIY front, try a sparkplug...

--
Cats, coffee, chocolate...vices to live by

On 3 Dec 2005 18:53:05 -0800, "bschwand"
wrote:

Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

Any ideas ?

Buy hermetic connectors. The 10e-7 torr thermal vacuum chambers I
once tested space stuff in (for Gemini and Apollo) used Deutsch
connectors.

bschwand writes:

I want to build a device similar in some ways to a vacuum chamber.

Consider a standard bell jar and baseplate. Lot easier than trying to
build something yourself, and easy to see what's going on.

E.g. http://www.fishersci.com/

Thank you for setting me in the right direction. It would not be high
vacuum, probably at most 0.1 atmosphere. The spark plug idea is
brilliant, I'll try that and see if it works. I'll do some googling
about vacuum and feedthroughs.

bruno

I found something that will perfectly fit the bill he

http://www2.ceramtec.com/CatalogNew/View_PG_Desc2.cfm?SectionID=35&SubsectionID=233&Pa rtDesc1=One%20Conductor&PartDesc2=%2E050%20%5B1%2E 3%5D%20Dia%2E%20Conductor

for only $20, so I am not going to mess with spark plugs...

Thanks again. I can find anything once I know the correct keywords :-)

bruno

In article . com,
"bschwand" wrote:

Thank you for setting me in the right direction. It would not be high
vacuum, probably at most 0.1 atmosphere. The spark plug idea is
brilliant, I'll try that and see if it works. I'll do some googling
about vacuum and feedthroughs.

That isn't even low vacuum in most labs. Plain old epoxy, or mechanical
seals with teflon (or the spark plugs) should be fine for your
application - when people are concerned about outgassing, it's generally
at pressures a million, billion, or trillon times lower than where you
are working...

Where I mostly worked, "low vacuum" was in the 1-300 milliTorr range. 1
atmosphere is about 760 Torr. Most of what that lab considered high
vacuum was in the 10e-6 10e-7 Torr range; there are places which
consider that pretty high, and commonly work in the 10e-12 or -13 range.
Those people have outgassing concerns.

At 76 Torr, outgassing is not likely to be a significant issue.

--
Cats, coffee, chocolate...vices to live by

On 3 Dec 2005 18:53:05 -0800, "bschwand"
wrote:

Hi everybody,

I want to build a device similar in some ways to a vacuum chamber.

I built a vacuum chamber for aluminizing telescope mirrors. Mild
steel chamber, plate glass electrical pass thrus, held in place with
two part epoxy. 2x10e-5 torr consistently, with a few trips to
9x10e-6 torr.

Oh, and spark plugs work just fine at this range, but, all in all,
make terrible electrical pass thrus.

http://lerch.no-ip.com/atm (item 18)

The new and improved chamber:
http://lerch.no-ip.com/atm/Projects/...First_Coating/


Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15Kw generator project)
Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent.
Calvin Coolidge

"bschwand" wrote in message
oups.com...
Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

Any ideas ?

bruno

There are many ways to seal glass to metal. Kovar can be directly sealed to
Pyrex, vacuum tight!

Randy Hansen
SC Glass Tech
Scam Diego, Comi-fornia

On 3 Dec 2005 21:42:08 -0800, "bschwand"
wrote:

Thank you for setting me in the right direction. It would not be high
vacuum, probably at most 0.1 atmosphere. The spark plug idea is
brilliant, I'll try that and see if it works. I'll do some googling
about vacuum and feedthroughs.

bruno

Almost anything including duct tape will work at 0.1 atmosphere. No
sarcasm here, it really will. Epoxy works fine at considerably
below that level. So do O-rings.

On 3 Dec 2005 18:53:05 -0800, "bschwand"
wrote:

I want to build a device similar in some ways to a vacuum chamber.

So use a vacuum chamber. The scrap trade for lab scrap is a bit
obscure, but it is out there. S/H vacuum systems are there to be found
and I've always bought them for no more than scrap steel price. Pumps
OTOH are expensive, because there's a good market for those. The
_convenience_ of well-designed well-made vacuum plumbing is worth the
effort of searching for it.

In article ,
(James Lerch) wrote:

Oh, and spark plugs work just fine at this range, but, all in all,
make terrible electrical pass thrus.

Use Non-resistor spark plugs

--
Free men own guns, slaves don't
www.geocities.com/CapitolHill/5357/

bschwand wrote:

Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

Any ideas ?

bruno


Check out the Chemistry Dept. of your local University. Look at their
"glove boxes" I've worked in several Chem depts. and I think they are
exactly what you want.
...lew...

bschwand wrote:

Before you get too far, you might want to think about the effects of
your "gases" on your mechanical pump and its oil. On the other hand,
at .1 atmosphere, it might be best to just use old refrigerator
compressors and throw them away when you are done.'
While I think of it, at .1 atmosphere, you still have a lot of air in
there. That may well affect the accuracy of your experiments.


Pete Stanaitis
-----------------

Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

Any ideas ?

bruno

In article . com, bschwand
says...

Thank you for setting me in the right direction. It would not be high
vacuum, probably at most 0.1 atmosphere.

That's about 80 torr. You can use anything for
a feedthrough at those pressures.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

Try this guy..
murphyjunk.bizland.com
Mikes a good guy and he has a huge warehouse full of stuff like this
He ships everyday and prices are very fair
Ihave no stake in this at all

well the idea is to fill the thing with hydrogen, argon, co2, etc. then
pump some out. No air, just the gas under test.

bruno

bschwand wrote:
Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port.
Don't make it, buy it. What you want is a Kovar feedthrough. These
have a piece of Kovar rod that passes through a piece of ceramic
insulator, which also serves as the vacuum seal.
The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.
This is exactly why Kovar was developed. It matches the thermal
expansion of glass and ceramic materials, and also wets the glass,
providing a strong mechanical bond. it is what is used to make the
connections through vacuum tubes. If this is a hobby project, you
can salvage the base of an all-glass vacuum tube or CRT.

Jon

For 0.1 atmosphere, RTV around a wire is more than sufficient. The vacuum
side is only 14.7PSI and that really isn't much pressure trying to get in.
The reason for the glass seals and so forth is that when you are down at
nano torr values, the inflow is sufficient to drop that vacuum level real
fast. At 0.1 of air pressure, the inflow is so small that it will take
years to do significant damage to the vacuum. Remember that a steel (not
even a polished steel but just run of the mill steel surface) to rubber
interface holds air in a tire for many years in an automobile tire.

--
Why do penguins walk so far to get to their nesting grounds?

You also didn't indicate the size ,but this
http://cgi.ebay.com/Miniature-Techni...ZViewItemspaco
on ebay
item 7569065039
might fit your bill. Already has feed thrus




wrote:

bschwand wrote:

Before you get too far, you might want to think about the effects of
your "gases" on your mechanical pump and its oil. On the other hand,
at .1 atmosphere, it might be best to just use old refrigerator
compressors and throw them away when you are done.'
While I think of it, at .1 atmosphere, you still have a lot of air in
there. That may well affect the accuracy of your experiments.


Pete Stanaitis
-----------------

Hi everybody,

I want to build a device similar in some ways to a vacuum chamber. It
should be able to be filled with various gases, a various pressures. In
the chamber, there will be some electrical device. As the device runs,
I want to mesure different things: how the heat produced is eliminated
depending on the type of gas, its pressure, how is EM radiation
released inside, etc.

So basically I need a gas tight enclosure, probably stainless steel or
some other non-reactive metal, with some gas ports on it to fill and
empty it (no problem), a door to swap the device inside (no problem),
some ports for electrical connections (problem).

I do not know how to make an electrically insulated, vacuum and heat
resistant electrical port. The material of the port needs to be as
inert and heat resistant as possible, it can not release gases or any
contaminant under vacuum (thus drilling a hole in the chamber, putting
a rod through and sealing it with epoxy or any resin won't work). I
thought of using glass, but I can not fuse the glass to the metal
because of the different thermal expansion rate of glass and metal.

Any ideas ?

bruno


jk

In article . com,
bschwand wrote:
well the idea is to fill the thing with hydrogen, argon, co2, etc. then
pump some out. No air, just the gas under test.

There are tons of vacuum pumps on ebay. I bought a nice welch pump
for 130 dollars. This pump will pull .02 Torr on a tight system
and will pump .5 torr with very crude plumbing (like automotive
PS rubber hose). Way more than you say you need (.1 atm which is 76 torr).

It can pump down a small 1 gal bell jar in 10 seconds.
BTW, I bought a bell jar from fisher scientific. It works but the
glass is very poor. The price was right though at ~50 bucks.

However it sounds like you might learn a lot by looking at Sam's
laser page. Google for it. There is a ton of info there that
might be right up your alley.

chuck

Hey, funny you say that, I have precisely been re-reading sam's laser
and specifically the vacuum page !

bruno