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here are my questions

1) how much ultimate vacuum i can achive with a diffusion pump setup
bellow

a) without a cold trap ( and oil backstreaming problem that go's
with it )

b) with a cold trap

c) a cheap an easy way to replace the LN2 coolant for the cold trap


2) the pros an cons of air cooled VS liquid cooled diffusion pump

3) on a liquid cooled VD pump can a radiator with a fan and a
circulator pump be used instead of running faucette water

and at last

4) what is the ultimate vacuum that can be substained in a
permanently seal vessel with or without a getter
ex:( CRT tubes, magnetron tubes, radio tubes, ect, ect, ect )

i hope i do not ask too much questions for my first time but
i am looking to build a small high vacuum pumping station with
used parts and i want the best setup for the least money and easy
to move i want to use this setup for making neon tubes and some
vacuum plating of small parts a small 2 or 3 inch dia VD pump
would be enought for me

any help appreciated

On Wednesday, October 29, 2003, at 12:35 PM, nano_tronics wrote:

here are my questions

1) how much ultimate vacuum i can achive with a diffusion pump setup
bellow

a) without a cold trap (and oil backstreaming problem that goes
with it )

Depending on the oil and how clean your rig is, probably 1x10^-5. You
really don't want to run without a cold trap, in my opinion.

b) with a cold trap

Again "depending", perhaps 1x10^-8 with LN2.

c) a cheap an easy way to replace the LN2 coolant for the cold trap

Dry ice and acetone. You won't get as low an ultimate vacuum, perhaps
1x10^-6.

2) the pros and cons of air cooled VS liquid cooled diffusion pump

This should be self-evident.

liquid cooled
pro: better heat removal / condensation
con: complexity, source of cool water

air cooled
pro: simplicity, lower cost
con: not so good condensation of working fluid

3) on a liquid cooled VD pump can a radiator with a fan and a
circulator pump be used instead of running faucet water

I don't see why not. You might need a rather large radiator and fan
rig with a low ambient temperature to get the temperature down to tap
water temperature, which is often as cold as 50-60 degrees by the ground
the supply pipes run through. Or you might consider putting together a
chiller. Perhaps an old air conditioner, dehumidifier, or other AC unit
could be cannibalized and turned into a heat exchanger. But I've been
told that air-cooled diffusion pumps work just fine, and virtually all
leak detectors use them, and achieve very reasonable vacuums with LN2
in the cold trap.

and at last

4) what is the ultimate vacuum that can be substained in a
permanently seal vessel with or without a getter
ex:( CRT tubes, magnetron tubes, radio tubes, ect, ect, ect )

There are too many possible variables to answer this. variables include:

* how clean the vessel and contained materials are, including fingerprints

* operating temperature

* what materials are used in your device - many materials out-gas or you
might have virtual leaks such as welds or tiny voids in a pinch-off or glass
to metal seal, especially in home-brew devices.

i hope i do not ask too much questions for my first time

Hah! Not possible- how else (other than reading certain hard to find books)
will you learn? Ask away!

I am only a beginner myself (and perhaps someone with more experience may
disagree with some of my answers above - I bow to anyone's superior wisdom.

Perhaps I shouldn't even give advice, my practical experience is restricted
to working with really nice space simulation chambers (designed by
professionals), reading available literature, and listening to people more
knowledgeable than I.

I do have my own high vacuum system - a Veeco VE-300 that I scored at an
auction for the outrageously low sum of $20. It needed a _lot_ of cleaning
though, and it didn't come with the bell jar or roughing pump. I already had
a roughing pump though, and a friend gave me an even larger one. I am still
shopping around for a bell jar I can afford.

Fortunately, a generous friend with more experience than I, who owns his own
home-brew high vacuum system, was willing to donate a lot of time and
expensive materials (DC704, woohoo!) to the rebuild, so some time this winter
I should be able to finish the last details (it's waiting for me to fabricate
a new mount for the new larger, roughing pump) and huff that sucker down!

Best of luck with your system.

- Bill "Gomez" Lemieux

Was a 12 inch by 17 inch glass bell jar and screen on eBay a few
days ago... might still be there. Price was somewhere around $50
when I saw it last.

Ken Hunter

OOPS...

Sorry, it sold yesterday... see eBay Item number: 2566818474
Keep checking eBay, I've seen 24 inch Stainless Steel jars sell for
$49.00 and the same jar sell for $350.00 depends who is bidding!

Ken Hunter

--- In VacuumX@..., "Ken Hunter" <atm_ken_hunter@y...>
wrote:

Was a 12 inch by 17 inch glass bell jar and screen on eBay a few
days ago... might still be there. Price was somewhere around $50
when I saw it last.

Ken Hunter

--- In VacuumX@..., Gomez <gomez@o...> wrote:

I am still shopping around for a bell jar I can afford.

- Bill "Gomez" Lemieux

You'll have to search eBay for Bell Jar, refine the search for
completed items and look for October 28 ...

Ken Hunter

--- In VacuumX@..., "Ken Hunter" <atm_ken_hunter@y...>
wrote:

Was a 12 inch by 17 inch glass bell jar and screen on eBay a few
days ago... might still be there. Price was somewhere around $50
when I saw it last.

Ken Hunter

--- In VacuumX@..., Gomez <gomez@o...> wrote:

I am still shopping around for a bell jar I can afford.

- Bill "Gomez" Lemieux

On Wednesday, October 29, 2003, at 04:21 PM, Ken Hunter wrote:

Was a 12 inch by 17 inch glass bell jar and screen on eBay a few
days ago... might still be there. Price was somewhere around $50
when I saw it last.

Believe me, I was watching that one closely. It was exactly the size
I need (12" ID). It jumped to $250 or so shortly before it closed.
My budget will probably have to stay around $100.

I can find one at a live auction eventually. I have seen them before,
and for low prices.

Thanks for thinking of me, though.

- Bill "Gomez" Lemieux,
Denver, Colorado



............................
IBM, UBM, we all BM for IBM.

--- In VacuumX@..., Gomez <gomez@o...> wrote:

On Wednesday, October 29, 2003, at 12:35 PM, nano_tronics wrote:

here are my questions

1) how much ultimate vacuum i can achive with a diffusion pump

setup

bellow

a) without a cold trap (and oil backstreaming problem that goes
with it )

Depending on the oil and how clean your rig is, probably 1x10^-

5. You

really don't want to run without a cold trap, in my opinion.

b) with a cold trap

Again "depending", perhaps 1x10^-8 with LN2.

c) a cheap an easy way to replace the LN2 coolant for the cold

trap

Dry ice and acetone. You won't get as low an ultimate vacuum,

perhaps

1x10^-6.

2) the pros and cons of air cooled VS liquid cooled diffusion

pump

This should be self-evident.

liquid cooled
pro: better heat removal / condensation
con: complexity, source of cool water

air cooled
pro: simplicity, lower cost
con: not so good condensation of working fluid

3) on a liquid cooled VD pump can a radiator with a fan and a
circulator pump be used instead of running faucet water

I don't see why not. You might need a rather large radiator and

fan

rig with a low ambient temperature to get the temperature down to

tap

water temperature, which is often as cold as 50-60 degrees by the

ground

the supply pipes run through. Or you might consider putting

together a

chiller. Perhaps an old air conditioner, dehumidifier, or other AC

unit

could be cannibalized and turned into a heat exchanger. But I've

been

told that air-cooled diffusion pumps work just fine, and virtually

all

leak detectors use them, and achieve very reasonable vacuums with

LN2

in the cold trap.

and at last

4) what is the ultimate vacuum that can be substained in a
permanently seal vessel with or without a getter
ex:( CRT tubes, magnetron tubes, radio tubes, ect, ect, ect )

There are too many possible variables to answer this. variables
include:

* how clean the vessel and contained materials are, including
fingerprints

* operating temperature

* what materials are used in your device - many materials out-gas

or you

might have virtual leaks such as welds or tiny voids in a pinch-off

or

glass
to metal seal, especially in home-brew devices.

i hope i do not ask too much questions for my first time

Hah! Not possible- how else (other than reading certain hard to

find

books)
will you learn? Ask away!

I am only a beginner myself (and perhaps someone with more

experience

may
disagree with some of my answers above - I bow to anyone's superior
wisdom.

Perhaps I shouldn't even give advice, my practical experience is
restricted
to working with really nice space simulation chambers (designed by
professionals), reading available literature, and listening to

people

more
knowledgeable than I.

I do have my own high vacuum system - a Veeco VE-300 that I

scored at

an
auction for the outrageously low sum of $20. It needed a _lot_ of
cleaning
though, and it didn't come with the bell jar or roughing pump. I
already had
a roughing pump though, and a friend gave me an even larger one. I

am

still
shopping around for a bell jar I can afford.

Fortunately, a generous friend with more experience than I, who

owns

his own
home-brew high vacuum system, was willing to donate a lot of time

and

expensive materials (DC704, woohoo!) to the rebuild, so some time

this

winter
I should be able to finish the last details (it's waiting for me to
fabricate
a new mount for the new larger, roughing pump) and huff that sucker
down!

Best of luck with your system.

- Bill "Gomez" Lemieux

about the no4 question what kind of vacuum are we taking about in CTR
tubes with the getter are they in the high vacuum range or in the
ultra high vacuum range

and if all precaution are take ex ( real good cleaning , glow
discharge, vacuum baking, ect ) can it be possible to go in the UHV
range without degradation for a permanently seal vacuum tube made of
low outgasing material or will it need to be pumped as long as need
to stay in this range

the unit you are using is it torr, mbar or pas

On Wednesday, October 29, 2003, at 05:54 PM, nano_tronics wrote:

about the no4 question what kind of vacuum are we taking about in CTR
tubes with the getter are they in the high vacuum range or in the
ultra high vacuum range

NO4?? I didn't see that. I've no idea what you're talking about.

and if all precaution are take ex ( real good cleaning , glow
discharge, vacuum baking, ect ) can it be possible to go in the UHV
range without degradation for a permanently seal vacuum tube made of
low outgasing material or will it need to be pumped as long as need
to stay in this range

Someone else who knows more should answer this, but I see no reason
why a good clean tube connected to a good HV system could not go UHV
once it's sealed and the getter fired properly. But my knowledge of
amateur-made permanently sealed UHV devices is sketchy at best!

the unit you are using is it torr, mbar or pas

Any time you see someone talking about vacuum in terms of 1 x 10 ^ -n,
they are probably talking about torr. That's the only term I'm very
familiar with, although I know there are others, and it's what all the
gauges I've seen are calibrated in. Even though Torr is a stupid unit
of measure. :)

- Gomez
.....................................................
Cryptographer Barbie says, "Gee, security is _hard_!"

--- In VacuumX@..., Gomez <gomez@o...> wrote:

On Wednesday, October 29, 2003, at 05:54 PM, nano_tronics wrote:

about the no4 question what kind of vacuum are we taking about in

CTR

tubes with the getter are they in the high vacuum range or in the
ultra high vacuum range

NO4?? I didn't see that. I've no idea what you're talking about.

and if all precaution are take ex ( real good cleaning , glow
discharge, vacuum baking, ect ) can it be possible to go in the

UHV

range without degradation for a permanently seal vacuum tube made

of

low outgasing material or will it need to be pumped as long as

need

to stay in this range

Someone else who knows more should answer this, but I see no

reason

why a good clean tube connected to a good HV system could not go UHV
once it's sealed and the getter fired properly. But my knowledge of
amateur-made permanently sealed UHV devices is sketchy at best!

the unit you are using is it torr, mbar or pas

Any time you see someone talking about vacuum in terms of 1 x 10

^ -n,

they are probably talking about torr. That's the only term I'm very
familiar with, although I know there are others, and it's what all

the

gauges I've seen are calibrated in. Even though Torr is a stupid

unit

of measure. :)

- Gomez
.....................................................
Cryptographer Barbie says, "Gee, security is _hard_!"

ok now i understand , i tought that to have an UVH in a closed seal
container it was needed to be pumped as long as it need to be
substained because of constant outgasing of container material i
understand that the getter play a big roles in stabilyzing the vacuum
if every proceding step is taken care of for reaching the UVH barrier

and torr can be translate to hg/mm i ask this question because it
gets confusing when looking for spec for VD pumps many of them are in
mbar some in pascal and other in torr i prefer to work with torr too
it is less confusing

Comments:
--- In VacuumX@..., "nano_tronics" <nortronics@s...>
wrote:

here are my questions

1) how much ultimate vacuum i can achive with a diffusion pump

setup

bellow

a) without a cold trap ( and oil backstreaming problem that go's
with it )

b) with a cold trap

c) a cheap an easy way to replace the LN2 coolant for the cold

trap

Here's a hair-brained idea. Since once a reasonable vacuum level is
achieved (1 micron or whatever it takes to start the diffusion
pump) - the actual mass flow through the cold trap is very low.
Therefore would it be possible to use some of the thermo-electric
cooling elements (Peltier devices) to cool the baffle plates? Total
heat flow will be low (perhaps mostly radiative), and the Peltiers
can be arranged in series to add temperature drops etc.

I had the chance to speak face to face with Don Mattox at the Indy
coating show yesterday, and I asked him about Peltier cold traps.
As far as he knows it hasn't been tried.

2) the pros an cons of air cooled VS liquid cooled diffusion pump

3) on a liquid cooled VD pump can a radiator with a fan and a
circulator pump be used instead of running faucette water

I was planning on doing exactly this. Can get a condensation pump
(intended to be used with a high efficiency fgurnace to remove flue
condensation) for about $50 or less - right off the shelf at
Grainger's etc. I think this would do the job. www.meci.com used to
have heater cores out of cars - which could be used for the radiator.

Another arrangement might be to use your cold trap AC system to
assist in cooling the closed-loop water used to chill a water-cooled
diffusion pump... This might allow you to use the fan and condenser
out of the AC to not only cool the cold trap but cool the diffusion
pump.

Lets see - seem to recall that a small 'window-banger' air
conditioner would pull about 5100 BTU/hr of heat out of the
evaporator. 5100 BTU/hr = 1400 watts or so. So a small AC would
(with a proper heat exchanger) cool a diffusion pump ~1400 watts
(which is a pretty big pump IMO).

Units conversions at:


Does anyone know if it is possible to over-cool a water-cooled
diffusion pump?

I have a line on a used evaporating station - no vac pumps but with
misc vac valves and a 18 inch diam x 30 tall bell jar. Filament
transformer is included. They want $500 which I think is a good
deal.

Also I took apart a commercial $0.50 quartz crystal the other day -
one of those HC-49 type package styles such as this one:

I used a coarse file to remove the top of the can. Inside the can
I found a quartz slab with metallized sides connected to the
leadouts. I am considering using these as film thickness monitors
in the evaporator. The price is right!

Anyone ever tried rolling their own film monitor?

-Bill

On Thursday, October 30, 2003, at 05:13 AM, nano_tronics wrote:

ok now i understand , i tought that to have an UVH in a closed seal
container it was needed to be pumped as long as it need to be
substained because of constant outgasing of container material

Obviously not, (if everything is done right) since things like high vacuum
capacitors and other ultra high vacuum devices work fine for decades without
so much as a getter. The tricks are getting everything clean enough, using
the right materials, bake-out, and so on.

i understand that the getter play a big roles in stabilyzing the vacuum
if every proceding step is taken care of for reaching the UVH barrier

and torr can be translate to hg/mm

Yes. 1000 Torr = 1000 mm/Hg @ 0C. 760 Torr = 1 atmosphere (standard)

i ask this question because it
gets confusing when looking for spec for VD pumps many of them are in
mbar some in pascal and other in torr i prefer to work with torr too
it is less confusing

There are many handy software utilities for most operating systems which
will convert any unit of measure into any other (within a measurement regime,
such as pressure). In MacOS, I use a tool called simply, "Convert" - very
handy, and worth every bit of the $15 shareware fee.

On Thursday, October 30, 2003, at 09:05 AM, arcstarter wrote:

Comments:
--- In VacuumX@..., "nano_tronics" <nortronics@s...>
wrote:

here are my questions

1) how much ultimate vacuum i can achive with a diffusion pump

setup

bellow

a) without a cold trap ( and oil backstreaming problem that go's
with it )

b) with a cold trap

c) a cheap an easy way to replace the LN2 coolant for the cold

trap

Here's a hair-brained idea. Since once a reasonable vacuum level is
achieved (1 micron or whatever it takes to start the diffusion
pump) - the actual mass flow through the cold trap is very low.
Therefore would it be possible to use some of the thermo-electric
cooling elements (Peltier devices) to cool the baffle plates? Total
heat flow will be low (perhaps mostly radiative), and the Peltiers
can be arranged in series to add temperature drops etc.

Temperature differential is created by moving heat. The greater the
differential, the more heat you have to move. While the heat load
entering the cold trap from the inside of the vacuum system may be
low, there is lots of other heat from the room and the material of
the trap itself, and its physical connections to the rest of the
system, which are constantly trying to warm it up. That actually
represents the lion's share of the heat you need to remove.

Now then, the amount of heat transported by each Peltier array is
proportional to the current through it. Furthermore, each Peltier
array has a maximum temperature differential it will sustain at its
maximum electrical ratings. For greater differentials, you have to
put several arrays in series. This is how very cold focal plane
array temperatures are achieved on some chilled CCD cameras for low
light photography (to reduce the inherent thermal noise of the array)

So, to get to LN2 or at least dry ice temperatures, you are going
to have to have 1) a lot of Peltier arrays in a series-parallel
arrangement and 2) an insane amount of power.

I had the chance to speak face to face with Don Mattox at the Indy
coating show yesterday, and I asked him about Peltier cold traps.
As far as he knows it hasn't been tried.

They are not very efficient. Moving fluid refrigeration is more
efficient. Their sole advantage is light weight and low cost.
Note that the portable coolers which use them have either large or
cigarette lighter cords to run off of a car's power. They also have
thicker insulation than regular ice chests. The owner's manuals
recommend that you not attempt to chill down the contents of the
cooler with the cooler alone, but rather that you put already-cold
foods into it and use the cooler only to help maintain a low
temperature.

In short, it could certainly be done, but at a very high cost
compared to the alternatives.

2) the pros an cons of air cooled VS liquid cooled diffusion pump

3) on a liquid cooled VD pump can a radiator with a fan and a
circulator pump be used instead of running faucette water

I was planning on doing exactly this. Can get a condensation pump
(intended to be used with a high efficiency fgurnace to remove flue
condensation) for about $50 or less - right off the shelf at
Grainger's etc. I think this would do the job. www.meci.com used to
have heater cores out of cars - which could be used for the radiator.

I believe that the efficiency of the diff. pump is related to how well the
walls are cooled. Warm water won't work as well as cool water, if the VD
is designed to use water cooling. A heat exchanger without refrigeration
will only lower your loop temp down to slightly above ambient, at best.

Another arrangement might be to use your cold trap AC system to
assist in cooling the closed-loop water used to chill a water-cooled
diffusion pump... This might allow you to use the fan and condenser
out of the AC to not only cool the cold trap but cool the diffusion
pump.

That's an interesting idea.

Does anyone know if it is possible to over-cool a water-cooled
diffusion pump?

That's a very good question! And one we should answer before anyone goes
to all the effort to try this.

I have a line on a used evaporating station - no vac pumps but with
misc vac valves and a 18 inch diam x 30 tall bell jar. Filament
transformer is included. They want $500 which I think is a good
deal.

Sweet! It's possible to do better, but that still seems reasonable.

Also I took apart a commercial $0.50 quartz crystal the other day -
one of those HC-49 type package styles such as this one:

I used a coarse file to remove the top of the can. Inside the can
I found a quartz slab with metallized sides connected to the
leadouts. I am considering using these as film thickness monitors
in the evaporator. The price is right!

Let us know how that works for you - I'm very curious about that myself.

Many times I have used old refrigerators or deep freezers as cooling plants for a variety of tasks.
Find a throwaway that still works but is rusty (no value) remove all the cooling equipment in one piece. (I often use a thin chisel to cut the tin)
If you have a friend who is a refrigeration mechanic then cutting and re-gassing is easier. (venting to atmosphere???)
Wrap the cooler plate around what you want to cool.
Seal in place to make a container, (Ive used epoxy and silicone, they both work) insulate the outside, fill with glycol and switch on.
If you can find a fridge with cooler pipes instead of a plate its even easier.
The radiator can be folded inside a large dia pipe with a fan to improve the temp differential and reduce footprint.

Questions:-
Would this produce a sufficient temp drop for the diffusion pump?
What about using it for cold traps?

Does anyone know if it is possible to over-cool a water-cooled
diffusion pump?

If this answer is yes then a thermostat would solve it.

Charles

--- In VacuumX@..., Gomez <gomez@o...> wrote:

On Thursday, October 30, 2003, at 05:13 AM, nano_tronics wrote:

ok now i understand , i tought that to have an UVH in a closed

seal

container it was needed to be pumped as long as it need to be
substained because of constant outgasing of container material

Obviously not, (if everything is done right) since things like

high

vacuum
capacitors and other ultra high vacuum devices work fine for

decades

without
so much as a getter. The tricks are getting everything clean

enough,

using
the right materials, bake-out, and so on.

i understand that the getter play a big roles in stabilyzing the
vacuum
if every proceding step is taken care of for reaching the UVH

barrier

and torr can be translate to hg/mm

Yes. 1000 Torr = 1000 mm/Hg @ 0C. 760 Torr = 1 atmosphere

(standard)

i ask this question because it
gets confusing when looking for spec for VD pumps many of them

are in

mbar some in pascal and other in torr i prefer to work with torr

too

it is less confusing

There are many handy software utilities for most operating

systems

which
will convert any unit of measure into any other (within a

measurement

regime,
such as pressure). In MacOS, I use a tool called

simply, "Convert" -

very
handy, and worth every bit of the $15 shareware fee.

thank you so much for answering my question now i know what can be
done and what cant, it is much clearer for me now :)

and dont worry when ill be able to get all my vacuum pump stuff ill
let you know for sure :)