Homemade High Vacuum Pump/System
I've been working on a high vacuum project that should make it easy for almost anyone to copy with only basic hand tools. The links are to the fusor site where I spend most of my time ranting about how easy building stuff can be. Maybe someone here will find the information useful.
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Re: Procedure to shut down a system without a gatevalve to the diffusionpump?
Vladimir,
Yes that true i should have put them up before. I put up some pictures on it now if perhaps anybody else want to comment on this or so.
Yes i think ill go with to cool it down in some way, it wont hurt.
The first picture is the whole system, and when i take of the lid to the left far left that is the oil baffle that sits just above the diffusionpump it looks like the other two pictures. It feels like its a good contruction on preventing oil from entering the chamber.
Just copy and past in the address bar.
Regards Henry
Henry,
Yes, I see now... The pictures would be great to avoid misunderstanding. Anyway, If your cool down your baffle and walls around it, it just will work better.
Best regards,
Vladimir
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Re: Procedure to shut down a system without a gatevalve to the diffusionpump?
Henry,
Yes, I see now... The pictures would be great to avoid misunderstanding. Anyway, If your cool down your baffle and walls around it, it just will work better.
Best regards,
Vladimir
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Show quoted text
On 7/24/2011 7:26 PM, henry_3507 wrote: Vladimir,
I think you misunderstood me a little. The whole chamber which is flat in contruction but long and where the diffusionpump is connected to in one end looks like an L that is turned 90 degree clockwise so its a natural baffle by it self. There has also been made an internal oil baffle to block out even more oil vapor if needed so its pretty much a double oil baffle. However it doesnt seem like any of this has been cooled more then by convection but i might put something on to do this since it cant hurt.
Thanks for your input and help!
Regard Henry
------------------------------------
Yahoo! Groups Links
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Re: Procedure to shut down a system without a gatevalve to the diffusionpump?
Vladimir,
I think you misunderstood me a little. The whole chamber which is flat in contruction but long and where the diffusionpump is connected to in one end looks like an L that is turned 90 degree clockwise so its a natural baffle by it self. There has also been made an internal oil baffle to block out even more oil vapor if needed so its pretty much a double oil baffle. However it doesnt seem like any of this has been cooled more then by convection but i might put something on to do this since it cant hurt.
Thanks for your input and help!
Regard Henry
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Re: Procedure to shut down a system without a gatevalve to the diffusionpump?
Henry,
Actually for 50 mm flange you can use any 50 mm flange valve, but you're right - it is practically impossible to find something for $50 including shipping... Just shipping cost may be more than $50 depending on your location.
Regarding your idea to use L type elbow - well, it may work. At least theoretically it must work in the molecular range of gas flow, i.e. at pressures something like below 5x10^-4 - 10^-3. What happens at higher pressures, in viscous range, - I can't say, all depends of temperatures and oil vapor pressure. I have no such experience, sorry. Hope your backing pump will pump down oil vapor. But don't forget there may be strong oil back migration via the pump and other components walls.
OK, you can try to use L shape elbow as a gate. But I would also cool it down with water pipe welded or soldered outside along its and insert inside additional optical dense plates (2-3) to work as a baffle.
Best regards,
Vladimir
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On 7/24/2011 5:48 PM, henry_3507 wrote: Vladimir,
Thanks for the answer!
Yes i would like a gate or butterfly valve there absolutely and i have searched. The only place i know is Ebay and the only one i found that would fit, and most likely pretty much the only one, goes for over 240$ incl. shipping. And 240$ is out of my economy since a lot of money have been spent on the rest, but sure cheap for a valve like that. Acceptable for me would be in the 50$ range incl. shipping but a NW50 gate or butterfly valve at that price would unfortunately most likely not exist as i see it.
The simple system i have is actually from a mass spectrometer incl. the chamber, diffusionpump and Bayard-Alpert tube with its controller but missing all the connection tubes, backingpump and so on that i had to look for during several month now to get.
The bits and pieces of this mass spectrometer had been all taken apart, not by me, and put in a boxes so i dont know if all the things to the diffusionpump were there like a valve but i think it was since in the other boxes what that belonged together were together. The only thing that was missing were one half of a little special composite sealant to the diffusion pump and that was originally the only bit i needed to put the DP to the chamber the first time, now i have bought a aluminum from Ebay. If there had been used an isolation valve i see as this would have been in this box.
The pump used for this mass spectrometer is a small cute Edwards EO50/60 and in the box there where no isolation valve what so ever but everything else that directly belonged to the chamber which make me think that it has been built without a such. Mass spectrometers are of course very sensitive to foreign gases and materials so it wont disturb the real measuring but the most likely lack of an isolation valve makes me think that due to the design of the chamber and the small pump used this wasnt necessary to use.
Just above the pump inlet there is several fins acting as a oil baffle sloping down to the DP for the oil to go back to it and the chamber it self is built like an L turned 90 degrees to the right where the pump then is hanging in the left bottom sort of speak. This makes it 100% optical dense so no oil at all should be able to get into the chamber even without a isolation valve to the diffusion pump.
But anyone would more then gladly tell me wrong about this so i know because this is only a theory of mine, i havent been into high vacuum before.
I might be able to put up some picture on it if needed if there might be something that is unclear or so.
Regards Henry
------------------------------------
Yahoo! Groups Links
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Re: Procedure to shut down a system without a gatevalve to the diffusionpump?
Vladimir,
Thanks for the answer!
Yes i would like a gate or butterfly valve there absolutely and i have searched. The only place i know is Ebay and the only one i found that would fit, and most likely pretty much the only one, goes for over 240$ incl. shipping. And 240$ is out of my economy since a lot of money have been spent on the rest, but sure cheap for a valve like that. Acceptable for me would be in the 50$ range incl. shipping but a NW50 gate or butterfly valve at that price would unfortunately most likely not exist as i see it.
The simple system i have is actually from a mass spectrometer incl. the chamber, diffusionpump and Bayard-Alpert tube with its controller but missing all the connection tubes, backingpump and so on that i had to look for during several month now to get.
The bits and pieces of this mass spectrometer had been all taken apart, not by me, and put in a boxes so i dont know if all the things to the diffusionpump were there like a valve but i think it was since in the other boxes what that belonged together were together. The only thing that was missing were one half of a little special composite sealant to the diffusion pump and that was originally the only bit i needed to put the DP to the chamber the first time, now i have bought a aluminum from Ebay. If there had been used an isolation valve i see as this would have been in this box.
The pump used for this mass spectrometer is a small cute Edwards EO50/60 and in the box there where no isolation valve what so ever but everything else that directly belonged to the chamber which make me think that it has been built without a such. Mass spectrometers are of course very sensitive to foreign gases and materials so it wont disturb the real measuring but the most likely lack of an isolation valve makes me think that due to the design of the chamber and the small pump used this wasnt necessary to use.
Just above the pump inlet there is several fins acting as a oil baffle sloping down to the DP for the oil to go back to it and the chamber it self is built like an L turned 90 degrees to the right where the pump then is hanging in the left bottom sort of speak. This makes it 100% optical dense so no oil at all should be able to get into the chamber even without a isolation valve to the diffusion pump.
But anyone would more then gladly tell me wrong about this so i know because this is only a theory of mine, i havent been into high vacuum before.
I might be able to put up some picture on it if needed if there might be something that is unclear or so.
Regards Henry
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Re: Procedure to shut down a system without a gatevalve to the diffusionpump?
Henry,
You done a great job! Please don't destroy it trying to use difpump without gate! There may be a lot of scenarios how to use it without gate, and on practice they all have negative results, sooner or later you run into a great troubles! You can try to estimate all risks, but IT NEVER WILL WORK FINE! Neither when it starts up, nor when it shut down. Don't forget that oil vapor is a serial killer for coatings, especially for metal ones.
I guess your pump doesn't has 500 mm input flange. So go to any online auction and you'll find cheap (sometimes very cheap) gate valve with manual control. I also would look for water cooled baffle. Install gate valve at least and enjoy! Trust me, you'll save more money, time and your own nervous with any gate valve!
Good luck!
Vladimir
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On 7/23/2011 4:24 PM, henry_3507 wrote: Hello guys!
I have finally built together a small simple high vacuum system with a diffusionpump and the vacuum only goes up from little under 1 milliTorr to 1.2 Torr in 2 days when all valves are shut and that is fine with me so it is holding the vacuum ok as i see it, might also be some degas involved.
I want to test the diffusionpump ASAP so i can start making small mirrors but i dont know if the shutdown procedure i think of is right to do without a gatevalve.
The diffusionpump is connected directly to the chamber the rest is built with one valve to its discharge and one valve to the chamber and these two are then connected to a tee and then the this is connected to the backing pump with a bellow tube and thats it.
To start it all is of course very easy but to shut it down with only two valves is something i want to be sure on if it works as i think of to do so without getting oil into the chamber or anything.
This is what i think might happen and/or will work and when i shut it down it all has to do with the diffusionpump as i see it:
As long as it is hot it pumps and thus must have the backing pump going all the time i guess or could the discharge valve be closed right away or as soon as it is only a little cooler? The very small amount of air in the bottom wont cause any oil to go into the chamber since this air will try to go up into the chamber and draw any oil from the oil curtain with it?
Or should i carefully monitor the discharge pressure and as soon as it starts to go down i shut the valve since i then see this to indicate that the dp is so cool that it cant hold down the air in the bottom anymore so air is then starting to be sucked back through the pump into the chamber from the discharge?
Will any of these scenarios work or will it pull back oil into the chamber or doesnt it matter since there might be so little air in the lower part of the diffusionspump that there wont be any problems at all no matter what i choose to do?
Im very concern of this so it wont go south very quickly all of a sudden, so any help with this would be highly appreciated so i know if this might work with only 2 valves and no gatevalve to the DP.
Thanks a lot!
Regards Henry
------------------------------------
Yahoo! Groups Links
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Procedure to shut down a system without a gatevalve to the diffusionpump?
Hello guys!
I have finally built together a small simple high vacuum system with a diffusionpump and the vacuum only goes up from little under 1 milliTorr to 1.2 Torr in 2 days when all valves are shut and that is fine with me so it is holding the vacuum ok as i see it, might also be some degas involved.
I want to test the diffusionpump ASAP so i can start making small mirrors but i dont know if the shutdown procedure i think of is right to do without a gatevalve.
The diffusionpump is connected directly to the chamber the rest is built with one valve to its discharge and one valve to the chamber and these two are then connected to a tee and then the this is connected to the backing pump with a bellow tube and thats it.
To start it all is of course very easy but to shut it down with only two valves is something i want to be sure on if it works as i think of to do so without getting oil into the chamber or anything.
This is what i think might happen and/or will work and when i shut it down it all has to do with the diffusionpump as i see it:
As long as it is hot it pumps and thus must have the backing pump going all the time i guess or could the discharge valve be closed right away or as soon as it is only a little cooler? The very small amount of air in the bottom wont cause any oil to go into the chamber since this air will try to go up into the chamber and draw any oil from the oil curtain with it?
Or should i carefully monitor the discharge pressure and as soon as it starts to go down i shut the valve since i then see this to indicate that the dp is so cool that it cant hold down the air in the bottom anymore so air is then starting to be sucked back through the pump into the chamber from the discharge?
Will any of these scenarios work or will it pull back oil into the chamber or doesnt it matter since there might be so little air in the lower part of the diffusionspump that there wont be any problems at all no matter what i choose to do?
Im very concern of this so it wont go south very quickly all of a sudden, so any help with this would be highly appreciated so i know if this might work with only 2 valves and no gatevalve to the DP.
Thanks a lot!
Regards Henry
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I would expect that would not be a problem as long as you are pumping faster than it?out-gasses. ;-)
On Sun, Jun 19, 2011 at 7:21 PM, Guy Brandenburg <gfbrandenburg@...> wrote:
I use an ordinary reinforced automobile radiator hose at one point in our setup. I wonder if things would be better if I used something else.
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S, brian whatcott pi?e:
On 6/19/2011 12:06 AM, Simon
Quellen Field wrote:
?
D. Finding some low vapor pressure compound that is a
liquid at room temp
? ? ?but a gas at some reasonable temperature (i.e. the
steam idea, but with
? ? ?something that doesn't need to be chilled).
It is unnecessary to attempt to produce a vacuum lower than the
vapor pressure of water at room temperature.? The device in
question WORKS at the vapor pressure of room temperature water
vapor.
The zeolite then gets hot, and the water container freezes down.?
In fact, if the whole container is filled with a vacuum
considerably higher than the vapor pressure of water of water at
room temperature, a small part of the capacity of the zeolite is
used to pull the rough? vacuum down further.??? A zeolite
container with enough solids to sustain several cooling cycles and
the initial pull-down cycle, which would be controled with a stop
cock between water reservoir and zeolite reservoir could serve the
purpose., I suspect.
Brian W
I'm not sure. I try with water ejector and got 25mBar but the result
is not good. It work's but the temperature is just to high. (18 ...
20 degres C). So probably little more vacuum is needed.
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S, Simon Quellen Field pi?e:
?
5. Buying a $130 roughing pump and a $30
inverter for a car.
I like to buy vacuum pump for $130. Cheapest I can get
here is $350.
Don't be silly. That's what the Internet is for.
""
As I already say. That pump is just nice to see. But import taxes
and distribution take the price over $250. Sorry.
[Note to others on the list -- this is a great price on a
nice pump.]
Hmm that seems possible to do. Just don't know where
to get that stuff. So just need to get something dense
and with low vapour presure. Oils seem little to light.
aprox 850kg/m3 but have wapour pressure far below 1
mbar. So just something heavier, nontoxic, and cheaply
available.
Olive oil is fine, just add some heavy powder:
""
""
A dollar a pound for 30 pounds. That would make 3 liters of
very heavy olive oil.
Use a valve and cycle it as many times as you like.
If you connect the bottom of the pipe to a cheap pump (like
the car intake port pump, or a water
aspirator pump) then you need even less than 13 feet of
elevation. [This is the staging idea I
mentioned earlier.]
I'm just thinkering the that last option. (With pump at the end). I
do little research and seem that (probably) all oil's (for salads or
car engine) has vapour presure below 1mBar. So in this aspect no
problem. Adding some 'sand' will probably kill the pump, but just
straight oil can be used. I just wondered if I need elevation in
that case at all. (using right pump).
Does someone here have experiences if glass bottles can handle that
vacuum? The botles with soda have aprox 1 bar overpressure but I
don't know if they can handle vacuum or will implode.
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It's OK. With distance about 60 cm you can work up to about 5x10-4
torr. The problem is that Al thin films being deposited on substrate
capture gas molecules, and that issue decreases deposited film
reflectance. This is why we use as low pressure as possible and
highest deposition rates - to decrease the capture gas molecules
concentration in the deposited film. I deposit Al on a cold
substrate with about 40 A/s rate, mirror film thickness is about 800
- 1000 A (20-25 s deposition), and obtain reflectance about 92% at
about 450 - 700 nm wavelength range.
We use PVC reinforced hose for roughing, but high vacuum we obtain
with cryo pump...
On 6/19/2011 7:21 PM, Guy Brandenburg wrote:
toggle quoted message
Show quoted text
The distance from the coil to the mirror is about 60 cm (2
feet) in our chamber. Our pressure gauge, which I don't
necessarily believe, indicates that we get down to about 7 x
10^ -5 to 1 x 10^4 torr, depending on the day and how much
time we have to pump things down.?
I use an ordinary reinforced automobile radiator hose at
one point in our setup. I wonder if things would be better if
I used something else.
?
Guy Brandenburg, Washington, DC?
============================
From:
Vladimir Chutko
To:
VacuumX@...
Sent: Sun,
June 19, 2011 9:58:00 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
?
Molecules free mean path about 1 meter and more is
when pressure in the chamber is below about 2x10-4 torr.
Actually for Al evaporation than pressure is less, than
better. The best is below 2x10^-5 torr. I produce a good
Al mirrors with Cr underlayer starting evaporate Cr at
pressure about 8X10-6 - 10^-5 torr. After Cr evaporation
pressure drops down to (2-3)x10^-6 torr, and I start
evaporate Al.
On 6/19/2011 6:29 PM, Guy Brandenburg wrote:
Sorry, Vladimir, as Simon points out, I was
joking.?
The weird spelling was supposed to be a clue to
that. I should have added a smiley face for the
benefit of those who aren't familiar with American
slang, etc.
I think I get it down so that the mean distance
between collisions of air and aluminum molecules is
on the order of a meter. That is, if the OTHER
vacuum gauge is right.
Obviously, I mostly ignore the one that says
"zero". Anyway, it has a linear, rather than a
logarithmic scale.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent:
Sun, June 19, 2011 9:23:48 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
?
He was joking.
;-)
Carrying your analysis a little farther,
however, what is the vapor pressure of the
walls
of your vacuum chamber at room temperature?
But we're clearly getting pedantic here,
which is why I put a smiling face on my
original comment.
-----
Get a free science project every
week! ""
On Sun, Jun 19, 2011
at 5:36 PM, Vladimir Chutko <chutko@...>
wrote:
?
If you even passed through
indicated 10 torr, 10^-1 torr,
10^-3 torr, 10^-6 torr, 10^-9
torr, 10^-11 torr, 10^-14 torr,
and then your meter indicates
ZERO - it means that you have
reached edge of your meter
sensitivity, no more. You can't
say that you have no one air
molecule or atom there. Connect
mass-spectrometer with very high
sensitivity and try to see what
are in your chamber. If you see
nothing, it means that your
mass-spectrometer also has not
enough sensitivity. It is
actually very easy to calculate
how many gas molecules you need
to provide pressure 10-14 torr,
for instance. It should be about
10^6 molecules in
or something like that, as far
as I remember constants...
Regards,
Vladimir
On 6/19/2011 5:11 PM, Guy
Brandenburg wrote:
Watchoo mean, Simon?
I got a dial right THAR
on my vacuum pump and it
says plain as day that
Ah get down to a
pressure of ZERO. And
that means there ain't a
single molecule or atom
of air in that thar
vacyoom chamber. Beleeve
yoo mee. Yessiree bob.
?
Guy Brandenburg,
Washington, DC?
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent:
Sun, June 19, 2011
7:13:14 PM
Subject:
Re: [VacuumX] Re:
"Cheap" vacuum
?
Nothing gets to
zero.
;-)
Mine is getting to
70 microns (0.07
millimeters of
mercury, 0.001
kiloPascals, 0.01
millibars).
Sounds like you
might have a leak.
-----
Get a free
science
project every
week! ""
On
Sun, Jun 19,
2011 at 11:02
AM, brian
whatcott <betwys1@...>
wrote:
?
On
6/19/2011
10:38 AM,
Simon Quellen
Field wrote:
?
""
[Note to
others on the
list -- this
is a great
price on a
nice pump.]
I bought the
next step up
(theoretically)
- a 2 stage
for? about
$130.
Trouble is -
when I
obtained a
vacuum gauge,
it gets
nowhere near
zero!
Brian W
|
The distance from the coil to the mirror is about 60 cm (2 feet) in our chamber. Our pressure gauge, which I don't necessarily believe, indicates that we get down to about 7 x 10^ -5 to 1 x 10^4 torr, depending on the day and how much time we have to pump things down.? I use an ordinary reinforced automobile radiator hose at one point in our setup. I wonder if things would be better if I used something else.
? Guy Brandenburg, Washington, DC? ============================
From: Vladimir Chutko
To: VacuumX@...
Sent: Sun, June 19, 2011 9:58:00 PM
Subject: Re: [VacuumX] Re: "Cheap" vacuum
?
Molecules free mean path about 1 meter and more is when pressure in
the chamber is below about 2x10-4 torr. Actually for Al evaporation
than pressure is less, than better. The best is below 2x10^-5 torr.
I produce a good Al mirrors with Cr underlayer starting evaporate Cr
at pressure about 8X10-6 - 10^-5 torr. After Cr evaporation pressure
drops down to (2-3)x10^-6 torr, and I start evaporate Al.
On 6/19/2011 6:29 PM, Guy Brandenburg wrote:
Sorry, Vladimir, as Simon points out, I was joking.?
The weird spelling was supposed to be a clue to that. I
should have added a smiley face for the benefit of those who
aren't familiar with American slang, etc.
I think I get it down so that the mean distance between
collisions of air and aluminum molecules is on the order of a
meter. That is, if the OTHER vacuum gauge is right.
Obviously, I mostly ignore the one that says "zero".
Anyway, it has a linear, rather than a logarithmic scale.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent: Sun,
June 19, 2011 9:23:48 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
?
He was joking.
;-)
Carrying your analysis a little farther, however,
what is the vapor pressure of the walls
of your vacuum chamber at room temperature?
But we're clearly getting pedantic here, which is why
I put a smiling face on my
original comment.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 5:36
PM, Vladimir Chutko <chutko@...>
wrote:
?
If you even passed through indicated 10
torr, 10^-1 torr, 10^-3 torr, 10^-6 torr,
10^-9 torr, 10^-11 torr, 10^-14 torr, and
then your meter indicates ZERO - it means
that you have reached edge of your meter
sensitivity, no more. You can't say that
you have no one air molecule or atom
there. Connect mass-spectrometer with very
high sensitivity and try to see what are
in your chamber. If you see nothing, it
means that your mass-spectrometer also has
not enough sensitivity. It is actually
very easy to calculate how many gas
molecules you need to provide pressure
10-14 torr, for instance. It should be
about 10^6 molecules in
or something like that, as far as I
remember constants...
Regards,
Vladimir
On 6/19/2011 5:11 PM, Guy Brandenburg
wrote:
Watchoo mean, Simon? I got a
dial right THAR on my vacuum pump
and it says plain as day that Ah
get down to a pressure of ZERO.
And that means there ain't a
single molecule or atom of air in
that thar vacyoom chamber. Beleeve
yoo mee. Yessiree bob.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To: VacuumX@...
Sent:
Sun, June 19, 2011 7:13:14 PM
Subject:
Re: [VacuumX] Re: "Cheap"
vacuum
?
Nothing gets to zero.
;-)
Mine is getting to 70 microns
(0.07 millimeters of mercury,
0.001 kiloPascals, 0.01
millibars).
Sounds like you might
have a leak.
-----
Get a free science
project every week! ""
On
Sun, Jun 19, 2011 at
11:02 AM, brian whatcott
<betwys1@...>
wrote:
?
On
6/19/2011
10:38 AM,
Simon Quellen
Field wrote:
?
""
[Note to
others on the
list -- this
is a great
price on a
nice pump.]
I bought the
next step up
(theoretically)
- a 2 stage
for? about
$130.
Trouble is -
when I
obtained a
vacuum gauge,
it gets
nowhere near
zero!
Brian W
|
Molecules free mean path about 1 meter and more is when pressure in
the chamber is below about 2x10-4 torr. Actually for Al evaporation
than pressure is less, than better. The best is below 2x10^-5 torr.
I produce a good Al mirrors with Cr underlayer starting evaporate Cr
at pressure about 8X10-6 - 10^-5 torr. After Cr evaporation pressure
drops down to (2-3)x10^-6 torr, and I start evaporate Al.
On 6/19/2011 6:29 PM, Guy Brandenburg wrote:
toggle quoted message
Show quoted text
Sorry, Vladimir, as Simon points out, I was joking.?
The weird spelling was supposed to be a clue to that. I
should have added a smiley face for the benefit of those who
aren't familiar with American slang, etc.
I think I get it down so that the mean distance between
collisions of air and aluminum molecules is on the order of a
meter. That is, if the OTHER vacuum gauge is right.
Obviously, I mostly ignore the one that says "zero".
Anyway, it has a linear, rather than a logarithmic scale.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent: Sun,
June 19, 2011 9:23:48 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
?
He was joking.
;-)
Carrying your analysis a little farther, however,
what is the vapor pressure of the walls
of your vacuum chamber at room temperature?
But we're clearly getting pedantic here, which is why
I put a smiling face on my
original comment.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 5:36
PM, Vladimir Chutko <chutko@...>
wrote:
?
If you even passed through indicated 10
torr, 10^-1 torr, 10^-3 torr, 10^-6 torr,
10^-9 torr, 10^-11 torr, 10^-14 torr, and
then your meter indicates ZERO - it means
that you have reached edge of your meter
sensitivity, no more. You can't say that
you have no one air molecule or atom
there. Connect mass-spectrometer with very
high sensitivity and try to see what are
in your chamber. If you see nothing, it
means that your mass-spectrometer also has
not enough sensitivity. It is actually
very easy to calculate how many gas
molecules you need to provide pressure
10-14 torr, for instance. It should be
about 10^6 molecules in
or something like that, as far as I
remember constants...
Regards,
Vladimir
On 6/19/2011 5:11 PM, Guy Brandenburg
wrote:
Watchoo mean, Simon? I got a
dial right THAR on my vacuum pump
and it says plain as day that Ah
get down to a pressure of ZERO.
And that means there ain't a
single molecule or atom of air in
that thar vacyoom chamber. Beleeve
yoo mee. Yessiree bob.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To: VacuumX@...
Sent:
Sun, June 19, 2011 7:13:14 PM
Subject:
Re: [VacuumX] Re: "Cheap"
vacuum
?
Nothing gets to zero.
;-)
Mine is getting to 70 microns
(0.07 millimeters of mercury,
0.001 kiloPascals, 0.01
millibars).
Sounds like you might
have a leak.
-----
Get a free science
project every week! ""
On
Sun, Jun 19, 2011 at
11:02 AM, brian whatcott
<betwys1@...>
wrote:
?
On
6/19/2011
10:38 AM,
Simon Quellen
Field wrote:
?
""
[Note to
others on the
list -- this
is a great
price on a
nice pump.]
I bought the
next step up
(theoretically)
- a 2 stage
for? about
$130.
Trouble is -
when I
obtained a
vacuum gauge,
it gets
nowhere near
zero!
Brian W
|
Sorry, I didn't pay attention on smilings... :-) :-D :-P
Talking seriously - PLUS wall material vapor pressure at the given
temperature, PLUS gas permeation through the chamber walls and
seals, PLUS absorbed on the walls gas outgassing,.... it may be
calculated but I'm a little bit lazy... I can just say that vacuum
below 10^-7 - 10^-8 needs very special care. Pump down chamber, bake
it and then cool it down to zero K, and you'll get particles and,
probably, black holes self-creation!
Nobel prize is waiting for you!!!
;-) =-O
On 6/19/2011 6:23 PM, Simon Quellen Field wrote:
toggle quoted message
Show quoted text
He was joking.
;-)
Carrying your analysis a little farther, however, what is the
vapor pressure of the walls
of your vacuum chamber at room temperature?
But we're clearly getting pedantic here, which is why I put a
smiling face on my
original comment.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 5:36 PM,
Vladimir Chutko <chutko@...>
wrote:
If you even passed through indicated 10 torr,
10^-1 torr, 10^-3 torr, 10^-6 torr, 10^-9 torr,
10^-11 torr, 10^-14 torr, and then your meter
indicates ZERO - it means that you have reached
edge of your meter sensitivity, no more. You can't
say that you have no one air molecule or atom
there. Connect mass-spectrometer with very high
sensitivity and try to see what are in your
chamber. If you see nothing, it means that your
mass-spectrometer also has not enough sensitivity.
It is actually very easy to calculate how many gas
molecules you need to provide pressure 10-14 torr,
for instance. It should be about 10^6 molecules in
or something like
that, as far as I remember constants...
Regards,
Vladimir
On 6/19/2011 5:11 PM, Guy Brandenburg wrote:
Watchoo mean, Simon? I got a dial right
THAR on my vacuum pump and it says plain
as day that Ah get down to a pressure of
ZERO. And that means there ain't a single
molecule or atom of air in that thar
vacyoom chamber. Beleeve yoo mee. Yessiree
bob.
Guy Brandenburg, Washington, DC
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent:
Sun, June 19, 2011 7:13:14 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
Nothing gets to zero.
;-)
Mine is getting to 70 microns (0.07
millimeters of mercury, 0.001
kiloPascals, 0.01 millibars).
Sounds like you might have a
leak.
-----
Get a free science project
every week! ""
On Sun,
Jun 19, 2011 at 11:02 AM, brian
whatcott <betwys1@...>
wrote:
On 6/19/2011
10:38 AM, Simon
Quellen Field wrote:
""
[Note to
others on the
list -- this
is a great
price on a
nice pump.]
I bought the next step
up (theoretically) - a
2 stage for about
$130.
Trouble is - when I
obtained a vacuum
gauge, it gets nowhere
near zero!
Brian W
|
That's great! Negative eight-tenths of a bar! Wow! You sure you didn't create a black hole witrh that thing? ? ?;+)
?
Guy Brandenburg, Washington, DC? ============================
From: brian whatcott
To: VacuumX@...
Cc: Simon Quellen Field
Sent: Sun, June 19, 2011 8:27:03 PM
Subject: Re: [VacuumX] Re: "Cheap" vacuum
?
Sad to tell, by the time I sourced the 3 inch diam vacuum gauge and
plumbed it directly to the flare outlet on the pump, to read a
magnificent -0.8 bar - it was a little late to go to the dealer with
it
Ho hum
Brian W
On 6/19/2011 6:13 PM, Simon Quellen Field wrote:
Nothing gets to zero.
;-)
Mine is getting to 70 microns (0.07 millimeters of mercury, 0.001
kiloPascals, 0.01 millibars).
Sounds like you might have a leak.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 11:02 AM,
brian whatcott <betwys1@...>
wrote:
?
On 6/19/2011 10:38 AM, Simon
Quellen Field wrote:
?
""
[Note to others on the list -- this is
a great price on a nice pump.]
I bought the next step up (theoretically) - a 2
stage for? about $130.
Trouble is - when I obtained a vacuum gauge, it
gets nowhere near zero!
Brian W
|
Sorry, Vladimir, as Simon points out, I was joking.?
The weird spelling was supposed to be a clue to that. I should have added a smiley face for the benefit of those who aren't familiar with American slang, etc.
I think I get it down so that the mean distance between collisions of air and aluminum molecules is on the order of a meter. That is, if the OTHER vacuum gauge is right.
Obviously, I mostly ignore the one that says "zero". Anyway, it has a linear, rather than a logarithmic scale.
? Guy Brandenburg, Washington, DC? ============================
From: Simon Quellen Field
To: VacuumX@...
Sent: Sun, June 19, 2011 9:23:48 PM
Subject: Re: [VacuumX] Re: "Cheap" vacuum
?
He was joking. ;-)
Carrying your analysis a little farther, however, what is the vapor pressure of the walls of your vacuum chamber at room temperature?
But we're clearly getting pedantic here, which is why I put a smiling face on my
original comment. ----- Get a free science project every week! ""
On Sun, Jun 19, 2011 at 5:36 PM, Vladimir Chutko <chutko@...> wrote:
?
If you even passed through indicated 10 torr, 10^-1 torr, 10^-3
torr, 10^-6 torr, 10^-9 torr, 10^-11 torr, 10^-14 torr, and then
your meter indicates ZERO - it means that you have reached edge of
your meter sensitivity, no more. You can't say that you have no one
air molecule or atom there. Connect mass-spectrometer with very high
sensitivity and try to see what are in your chamber. If you see
nothing, it means that your mass-spectrometer also has not enough
sensitivity. It is actually very easy to calculate how many gas
molecules you need to provide pressure 10-14 torr, for instance. It
should be about 10^6 molecules in or something like that, as
far as I remember constants...
Regards,
Vladimir
On 6/19/2011 5:11 PM, Guy Brandenburg wrote:
Watchoo mean, Simon? I got a dial right THAR on my vacuum
pump and it says plain as day that Ah get down to a pressure
of ZERO. And that means there ain't a single molecule or atom
of air in that thar vacyoom chamber. Beleeve yoo mee. Yessiree
bob.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent: Sun,
June 19, 2011 7:13:14 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
?
Nothing gets to zero.
;-)
Mine is getting to 70 microns (0.07 millimeters of
mercury, 0.001 kiloPascals, 0.01 millibars).
Sounds like you might have a leak.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 11:02
AM, brian whatcott <betwys1@...>
wrote:
?
On 6/19/2011 10:38 AM,
Simon Quellen Field wrote:
?
""
[Note to others on the list --
this is a great price on a nice
pump.]
I bought the next step up (theoretically)
- a 2 stage for? about $130.
Trouble is - when I obtained a vacuum
gauge, it gets nowhere near zero!
Brian W
|
He was joking. ;-)
Carrying your analysis a little farther, however, what is the vapor pressure of the walls of your vacuum chamber at room temperature?
But we're clearly getting pedantic here, which is why I put a smiling face on my
original comment. ----- Get a free science project every week! ""
On Sun, Jun 19, 2011 at 5:36 PM, Vladimir Chutko <chutko@...> wrote:
?
If you even passed through indicated 10 torr, 10^-1 torr, 10^-3
torr, 10^-6 torr, 10^-9 torr, 10^-11 torr, 10^-14 torr, and then
your meter indicates ZERO - it means that you have reached edge of
your meter sensitivity, no more. You can't say that you have no one
air molecule or atom there. Connect mass-spectrometer with very high
sensitivity and try to see what are in your chamber. If you see
nothing, it means that your mass-spectrometer also has not enough
sensitivity. It is actually very easy to calculate how many gas
molecules you need to provide pressure 10-14 torr, for instance. It
should be about 10^6 molecules in or something like that, as
far as I remember constants...
Regards,
Vladimir
On 6/19/2011 5:11 PM, Guy Brandenburg wrote:
Watchoo mean, Simon? I got a dial right THAR on my vacuum
pump and it says plain as day that Ah get down to a pressure
of ZERO. And that means there ain't a single molecule or atom
of air in that thar vacyoom chamber. Beleeve yoo mee. Yessiree
bob.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent: Sun,
June 19, 2011 7:13:14 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
?
Nothing gets to zero.
;-)
Mine is getting to 70 microns (0.07 millimeters of
mercury, 0.001 kiloPascals, 0.01 millibars).
Sounds like you might have a leak.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 11:02
AM, brian whatcott <betwys1@...>
wrote:
?
On 6/19/2011 10:38 AM,
Simon Quellen Field wrote:
?
""
[Note to others on the list --
this is a great price on a nice
pump.]
I bought the next step up (theoretically)
- a 2 stage for? about $130.
Trouble is - when I obtained a vacuum
gauge, it gets nowhere near zero!
Brian W
|
If you even passed through indicated 10 torr, 10^-1 torr, 10^-3
torr, 10^-6 torr, 10^-9 torr, 10^-11 torr, 10^-14 torr, and then
your meter indicates ZERO - it means that you have reached edge of
your meter sensitivity, no more. You can't say that you have no one
air molecule or atom there. Connect mass-spectrometer with very high
sensitivity and try to see what are in your chamber. If you see
nothing, it means that your mass-spectrometer also has not enough
sensitivity. It is actually very easy to calculate how many gas
molecules you need to provide pressure 10-14 torr, for instance. It
should be about 10^6 molecules in cub.cm or something like that, as
far as I remember constants...
Regards,
Vladimir
On 6/19/2011 5:11 PM, Guy Brandenburg wrote:
toggle quoted message
Show quoted text
Watchoo mean, Simon? I got a dial right THAR on my vacuum
pump and it says plain as day that Ah get down to a pressure
of ZERO. And that means there ain't a single molecule or atom
of air in that thar vacyoom chamber. Beleeve yoo mee. Yessiree
bob.
?
Guy Brandenburg, Washington, DC?
============================
From:
Simon Quellen Field
To:
VacuumX@...
Sent: Sun,
June 19, 2011 7:13:14 PM
Subject:
Re: [VacuumX] Re: "Cheap" vacuum
?
Nothing gets to zero.
;-)
Mine is getting to 70 microns (0.07 millimeters of
mercury, 0.001 kiloPascals, 0.01 millibars).
Sounds like you might have a leak.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 11:02
AM, brian whatcott <betwys1@...>
wrote:
?
On 6/19/2011 10:38 AM,
Simon Quellen Field wrote:
?
""
[Note to others on the list --
this is a great price on a nice
pump.]
I bought the next step up (theoretically)
- a 2 stage for? about $130.
Trouble is - when I obtained a vacuum
gauge, it gets nowhere near zero!
Brian W
|
Sad to tell, by the time I sourced the 3 inch diam vacuum gauge and
plumbed it directly to the flare outlet on the pump, to read a
magnificent -0.8 bar - it was a little late to go to the dealer with
it
Ho hum
Brian W
On 6/19/2011 6:13 PM, Simon Quellen Field wrote:
toggle quoted message
Show quoted text
Nothing gets to zero.
;-)
Mine is getting to 70 microns (0.07 millimeters of mercury, 0.001
kiloPascals, 0.01 millibars).
Sounds like you might have a leak.
-----
Get a free science project every week! ""
On Sun, Jun 19, 2011 at 11:02 AM,
brian whatcott <betwys1@...>
wrote:
On 6/19/2011 10:38 AM, Simon
Quellen Field wrote:
""
[Note to others on the list -- this is
a great price on a nice pump.]
I bought the next step up (theoretically) - a 2
stage for about $130.
Trouble is - when I obtained a vacuum gauge, it
gets nowhere near zero!
Brian W
|
Simon Quellen Field