[EE] Vacuum plumbing

[Van Horn, David]

Is there a good laymans guide out there to creating a vacuum system? Valves etc
I am gearing up to produce small tubes filled with low pressure gases like neon/argon/xenon and I need to construct a manifold that I can use for the vac and gas process that won't leak as my gas volumes are very small.
Also leaking would contaminate the mix and possibly my gas supply as well, since it's glass flasks at below ambient pressure.

Most valves available at common sources leak badly in this application.

Pressures inside will be 10-20 microns up to maybe 4 torr.



--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
email: ***@backcountryaccess.com<mailto:***@backcountryaccess.com>

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[Richard Pytelewski]

David:


I am sure there is cost component here but the pressure you are talking about are used in freeze dryers; i.e., lyophilizers. Nothing about that technology is cheap but rooting around in that engineering area may provide the answer. Perhaps a starting point: http://www.labconco.com/category/freeze-dry-system-accessories


Good luck!


Rich

Freeze Dry System Parts & Accessories - Labconco<http://www.labconco.com/category/freeze-dry-system-accessories>
www.labconco.com
A wide selection of accessories for use with commercial and laboratory freeze dryers to meet any lyophilizing needs.




________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Van Horn, David <***@backcountryaccess.com>
Sent: Monday, October 30, 2017 12:52 PM
To: Microcontroller discussion list - Public.
Subject: [EE] Vacuum plumbing


Is there a good laymans guide out there to creating a vacuum system? Valves etc
I am gearing up to produce small tubes filled with low pressure gases like neon/argon/xenon and I need to construct a manifold that I can use for the vac and gas process that won't leak as my gas volumes are very small.
Also leaking would contaminate the mix and possibly my gas supply as well, since it's glass flasks at below ambient pressure.

Most valves available at common sources leak badly in this application.

Pressures inside will be 10-20 microns up to maybe 4 torr.



--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
email: ***@backcountryaccess.com<mailto:***@backcountryaccess.com>

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[John Gardner]

Hi David -

If you have access to Scientific American archives/The Amateur Scientist/

1950-1980 there are many discussions of DIY vacuum tech ancillary to every-

thing from homebrew Crooke's Tubes, Cyclotrons, you name it.

Might help - Who knows... "8)

...


On 10/30/17, Richard Pytelewski <***@hotmail.com> wrote:
> David:
>
>
> I am sure there is cost component here but the pressure you are talking
> about are used in freeze dryers; i.e., lyophilizers. Nothing about that
> technology is cheap but rooting around in that engineering area may provide
> the answer. Perhaps a starting point:
> http://www.labconco.com/category/freeze-dry-system-accessories
>
>
> Good luck!
>
>
> Rich
>
> Freeze Dry System Parts & Accessories -
> Labconco<http://www.labconco.com/category/freeze-dry-system-accessories>
> www.labconco.com
> A wide selection of accessories for use with commercial and laboratory
> freeze dryers to meet any lyophilizing needs.
>
>
>
>
> ________________________________
> From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Van
> Horn, David <***@backcountryaccess.com>
> Sent: Monday, October 30, 2017 12:52 PM
> To: Microcontroller discussion list - Public.
> Subject: [EE] Vacuum plumbing
>
>
> Is there a good laymans guide out there to creating a vacuum system? Valves
> etc
> I am gearing up to produce small tubes filled with low pressure gases like
> neon/argon/xenon and I need to construct a manifold that I can use for the
> vac and gas process that won't leak as my gas volumes are very small.
> Also leaking would contaminate the mix and possibly my gas supply as well,
> since it's glass flasks at below ambient pressure.
>
> Most valves available at common sources leak badly in this application.
>
> Pressures inside will be 10-20 microns up to maybe 4 torr.
>
>
>
> --
> David VanHorn
> Lead Hardware Engineer
>
> Backcountry Access, Inc.
> 2820 Wilderness Pl, Unit H
> Boulder, CO 80301 USA
> phone: [phone] x110
> email:
> ***@backcountryaccess.com<mailto:***@backcountryaccess.com>
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> PIClist, Microchip PIC<http://www.piclist.com/techref/piclist>
> www.piclist.com
> The PICList is a collection of people interested in the Microchip PIC
> processor.
>
>
>
> View/change your membership options at
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[Sean Breheny]

In chemistry, when air-free techniques are needed for air-reactive
chemicals, it is common to use either inert gas or vacuum. The manifold
which is used is called a Schlenk line. Valves are usually ground-glass or
teflon stopcocks. I am not sure about whether this can keep purity down to
10 microns but it is able to handle materials which would be harmed by even
a few ppm of oxygen.

On Mon, Oct 30, 2017 at 3:52 PM, Van Horn, David <
***@backcountryaccess.com> wrote:

>
> Is there a good laymans guide out there to creating a vacuum system?
> Valves etc
> I am gearing up to produce small tubes filled with low pressure gases like
> neon/argon/xenon and I need to construct a manifold that I can use for the
> vac and gas process that won't leak as my gas volumes are very small.
> Also leaking would contaminate the mix and possibly my gas supply as well,
> since it's glass flasks at below ambient pressure.
>
> Most valves available at common sources leak badly in this application.
>
> Pressures inside will be 10-20 microns up to maybe 4 torr.
>
>
>
> --
> David VanHorn
> Lead Hardware Engineer
>
> Backcountry Access, Inc.
> 2820 Wilderness Pl, Unit H
> Boulder, CO 80301 USA
> phone: [phone] x110
> email: ***@backcountryaccess.com<mailto:david.vanhorn@
> backcountryaccess.com>
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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[Van Horn, David]

The neon sign guys swear at vacuum grease and glass stopcocks. They aren't real clear as to what they do like.
The few people who make manifolds for neon are very hard to talk to.
There's some folks on youtube doing similar things, but I haven't had any luck contacting them either.

https://www.youtube.com/watch?v=jv9txBM9U5E for example


-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Sean Breheny
Sent: Monday, October 30, 2017 4:37 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Vacuum plumbing

In chemistry, when air-free techniques are needed for air-reactive chemicals, it is common to use either inert gas or vacuum. The manifold which is used is called a Schlenk line. Valves are usually ground-glass or teflon stopcocks. I am not sure about whether this can keep purity down to
10 microns but it is able to handle materials which would be harmed by even a few ppm of oxygen.

On Mon, Oct 30, 2017 at 3:52 PM, Van Horn, David < ***@backcountryaccess.com> wrote:

>
> Is there a good laymans guide out there to creating a vacuum system?
> Valves etc
> I am gearing up to produce small tubes filled with low pressure gases
> like neon/argon/xenon and I need to construct a manifold that I can
> use for the vac and gas process that won't leak as my gas volumes are very small.
> Also leaking would contaminate the mix and possibly my gas supply as
> well, since it's glass flasks at below ambient pressure.
>
> Most valves available at common sources leak badly in this application.
>
> Pressures inside will be 10-20 microns up to maybe 4 torr.
>
>
>
> --
> David VanHorn
> Lead Hardware Engineer
>
> Backcountry Access, Inc.
> 2820 Wilderness Pl, Unit H
> Boulder, CO 80301 USA
> phone: [phone] x110
> email: ***@backcountryaccess.com<mailto:david.vanhorn@
> backcountryaccess.com>
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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[Sean Breheny]

It wasn't clear to me that you wanted to ionize the inert gas. I agree then
that stopcocks are probably not good enough. PPM levels of remaining air
would be too much for you. You need to do what vacuum tube manufacturers do
- and I'm not 100% sure what that is.



On Mon, Oct 30, 2017 at 7:04 PM, Van Horn, David <
***@backcountryaccess.com> wrote:

> The neon sign guys swear at vacuum grease and glass stopcocks. They aren't
> real clear as to what they do like.
> The few people who make manifolds for neon are very hard to talk to.
> There's some folks on youtube doing similar things, but I haven't had any
> luck contacting them either.
>
> https://www.youtube.com/watch?v=jv9txBM9U5E for example
>
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> Of Sean Breheny
> Sent: Monday, October 30, 2017 4:37 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Vacuum plumbing
>
> In chemistry, when air-free techniques are needed for air-reactive
> chemicals, it is common to use either inert gas or vacuum. The manifold
> which is used is called a Schlenk line. Valves are usually ground-glass or
> teflon stopcocks. I am not sure about whether this can keep purity down to
> 10 microns but it is able to handle materials which would be harmed by
> even a few ppm of oxygen.
>
> On Mon, Oct 30, 2017 at 3:52 PM, Van Horn, David < david.vanhorn@
> backcountryaccess.com> wrote:
>
> >
> > Is there a good laymans guide out there to creating a vacuum system?
> > Valves etc
> > I am gearing up to produce small tubes filled with low pressure gases
> > like neon/argon/xenon and I need to construct a manifold that I can
> > use for the vac and gas process that won't leak as my gas volumes are
> very small.
> > Also leaking would contaminate the mix and possibly my gas supply as
> > well, since it's glass flasks at below ambient pressure.
> >
> > Most valves available at common sources leak badly in this application.
> >
> > Pressures inside will be 10-20 microns up to maybe 4 torr.
> >
> >
> >
> > --
> > David VanHorn
> > Lead Hardware Engineer
> >
> > Backcountry Access, Inc.
> > 2820 Wilderness Pl, Unit H
> > Boulder, CO 80301 USA
> > phone: [phone] x110
> > email: ***@backcountryaccess.com<mailto:david.vanhorn@
> > backcountryaccess.com>
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
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[Sean Breheny]

I am familiar with Carl Willis (the author of the video you linked to). I
don't know him personally but I've watched a bunch of his videos. I am
surprised if you can't contact him.


On Tue, Oct 31, 2017 at 12:16 AM, Sean Breheny <***@cornell.edu> wrote:

> It wasn't clear to me that you wanted to ionize the inert gas. I agree
> then that stopcocks are probably not good enough. PPM levels of remaining
> air would be too much for you. You need to do what vacuum tube
> manufacturers do - and I'm not 100% sure what that is.
>
>
>
> On Mon, Oct 30, 2017 at 7:04 PM, Van Horn, David <david.vanhorn@
> backcountryaccess.com> wrote:
>
>> The neon sign guys swear at vacuum grease and glass stopcocks. They
>> aren't real clear as to what they do like.
>> The few people who make manifolds for neon are very hard to talk to.
>> There's some folks on youtube doing similar things, but I haven't had any
>> luck contacting them either.
>>
>> https://www.youtube.com/watch?v=jv9txBM9U5E for example
>>
>>
>> -----Original Message-----
>> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
>> Of Sean Breheny
>> Sent: Monday, October 30, 2017 4:37 PM
>> To: Microcontroller discussion list - Public.
>> Subject: Re: [EE] Vacuum plumbing
>>
>> In chemistry, when air-free techniques are needed for air-reactive
>> chemicals, it is common to use either inert gas or vacuum. The manifold
>> which is used is called a Schlenk line. Valves are usually ground-glass or
>> teflon stopcocks. I am not sure about whether this can keep purity down to
>> 10 microns but it is able to handle materials which would be harmed by
>> even a few ppm of oxygen.
>>
>> On Mon, Oct 30, 2017 at 3:52 PM, Van Horn, David <
>> ***@backcountryaccess.com> wrote:
>>
>> >
>> > Is there a good laymans guide out there to creating a vacuum system?
>> > Valves etc
>> > I am gearing up to produce small tubes filled with low pressure gases
>> > like neon/argon/xenon and I need to construct a manifold that I can
>> > use for the vac and gas process that won't leak as my gas volumes are
>> very small.
>> > Also leaking would contaminate the mix and possibly my gas supply as
>> > well, since it's glass flasks at below ambient pressure.
>> >
>> > Most valves available at common sources leak badly in this application.
>> >
>> > Pressures inside will be 10-20 microns up to maybe 4 torr.
>> >
>> >
>> >
>> > --
>> > David VanHorn
>> > Lead Hardware Engineer
>> >
>> > Backcountry Access, Inc.
>> > 2820 Wilderness Pl, Unit H
>> > Boulder, CO 80301 USA
>> > phone: [phone] x110
>> > email: ***@backcountryaccess.com<mailto:david.vanhorn@
>> > backcountryaccess.com>
>> >
>> > --
>> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
>> > View/change your membership options at
>> > http://mailman.mit.edu/mailman/listinfo/piclist
>> >
>> --
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>> /listinfo/piclist
>>
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>> http://mailman.mit.edu/mailman/listinfo/piclist
>>
>
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[Sean Breheny]

In the comments for that video he describes what he does to make these. He
may not need any valves suitable for holding a high vacuum. It sounds like
the length of time between when he evacuates the tube and when he seals it
is rather short (minutes). Imagine if he had a plastic or rubber tube
connecting the stem of his tube to a manifold which had similar tubes going
to a vacuum gauge, vacuum pump, and inert gas tanks with valves. Even if
the valves leak at a rate which would cause a few microns of pressure after
a half hour, he can just seal off the stem of the tube (by melting it,
drawing it out, cutting it off, and then rounding-off the end).

On Tue, Oct 31, 2017 at 12:20 AM, Sean Breheny <***@cornell.edu> wrote:

> I am familiar with Carl Willis (the author of the video you linked to). I
> don't know him personally but I've watched a bunch of his videos. I am
> surprised if you can't contact him.
>
>
> On Tue, Oct 31, 2017 at 12:16 AM, Sean Breheny <***@cornell.edu> wrote:
>
>> It wasn't clear to me that you wanted to ionize the inert gas. I agree
>> then that stopcocks are probably not good enough. PPM levels of remaining
>> air would be too much for you. You need to do what vacuum tube
>> manufacturers do - and I'm not 100% sure what that is.
>>
>>
>>
>> On Mon, Oct 30, 2017 at 7:04 PM, Van Horn, David <
>> ***@backcountryaccess.com> wrote:
>>
>>> The neon sign guys swear at vacuum grease and glass stopcocks. They
>>> aren't real clear as to what they do like.
>>> The few people who make manifolds for neon are very hard to talk to.
>>> There's some folks on youtube doing similar things, but I haven't had
>>> any luck contacting them either.
>>>
>>> https://www.youtube.com/watch?v=jv9txBM9U5E for example
>>>
>>>
>>> -----Original Message-----
>>> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
>>> Behalf Of Sean Breheny
>>> Sent: Monday, October 30, 2017 4:37 PM
>>> To: Microcontroller discussion list - Public.
>>> Subject: Re: [EE] Vacuum plumbing
>>>
>>> In chemistry, when air-free techniques are needed for air-reactive
>>> chemicals, it is common to use either inert gas or vacuum. The manifold
>>> which is used is called a Schlenk line. Valves are usually ground-glass or
>>> teflon stopcocks. I am not sure about whether this can keep purity down to
>>> 10 microns but it is able to handle materials which would be harmed by
>>> even a few ppm of oxygen.
>>>
>>> On Mon, Oct 30, 2017 at 3:52 PM, Van Horn, David <
>>> ***@backcountryaccess.com> wrote:
>>>
>>> >
>>> > Is there a good laymans guide out there to creating a vacuum system?
>>> > Valves etc
>>> > I am gearing up to produce small tubes filled with low pressure gases
>>> > like neon/argon/xenon and I need to construct a manifold that I can
>>> > use for the vac and gas process that won't leak as my gas volumes are
>>> very small.
>>> > Also leaking would contaminate the mix and possibly my gas supply as
>>> > well, since it's glass flasks at below ambient pressure.
>>> >
>>> > Most valves available at common sources leak badly in this application.
>>> >
>>> > Pressures inside will be 10-20 microns up to maybe 4 torr.
>>> >
>>> >
>>> >
>>> > --
>>> > David VanHorn
>>> > Lead Hardware Engineer
>>> >
>>> > Backcountry Access, Inc.
>>> > 2820 Wilderness Pl, Unit H
>>> > Boulder, CO 80301 USA
>>> > phone: [phone] x110
>>> > email: ***@backcountryaccess.com<mailto:david.vanhorn@
>>> > backcountryaccess.com>
>>> >
>>> > --
>>> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
>>> > View/change your membership options at
>>> > http://mailman.mit.edu/mailman/listinfo/piclist
>>> >
>>> --
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>>> View/change your membership options at http://mailman.mit.edu/mailman
>>> /listinfo/piclist
>>>
>>> --
>>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
>>> View/change your membership options at
>>> http://mailman.mit.edu/mailman/listinfo/piclist
>>>
>>
>>
>
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[Van Horn, David]

I discovered a source of valves, Kontes high vacuum similar to part number 826500-0004
Not cheap, but less expensive on Ebay.

Now I need to find some writing on how to put the plumbing together. The basics I know, but it's the "how do you hold all this in position while flaming the tubes" part that has me wondering.

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[Sean Breheny]

What type of glass are you working with? You will need to actually melt
it, not just soften it. This will likely take an oxy-fuel torch -
especially if you are using Pyrex (and non-pyrex tends to crack when
cooling so it isn't easier)

On Oct 31, 2017 2:45 PM, "Van Horn, David" <
***@backcountryaccess.com> wrote:

> I discovered a source of valves, Kontes high vacuum similar to part number
> 826500-0004
> Not cheap, but less expensive on Ebay.
>
> Now I need to find some writing on how to put the plumbing together. The
> basics I know, but it's the "how do you hold all this in position while
> flaming the tubes" part that has me wondering.
>
> --
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[Van Horn, David]

Borosilicate aka pyrex. COE33. I have the appropriate torch and fuel/oxygen.

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Sean Breheny
Sent: Tuesday, October 31, 2017 2:05 PM
To: Microcontroller discussion list - Public.
Subject: RE: [EE] Vacuum plumbing

What type of glass are you working with? You will need to actually melt it, not just soften it. This will likely take an oxy-fuel torch - especially if you are using Pyrex (and non-pyrex tends to crack when cooling so it isn't easier)

On Oct 31, 2017 2:45 PM, "Van Horn, David" < ***@backcountryaccess.com> wrote:

> I discovered a source of valves, Kontes high vacuum similar to part
> number
> 826500-0004
> Not cheap, but less expensive on Ebay.
>
> Now I need to find some writing on how to put the plumbing together.
> The basics I know, but it's the "how do you hold all this in position
> while flaming the tubes" part that has me wondering.
>
> --
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[mike brown]

Anything labeled pyrex is soda-lime glass, you surely mean PYREX. Not
really sure where Pyrex stands right now.

On Oct 31, 2017 16:03, "Van Horn, David" <
***@backcountryaccess.com> wrote:

> Borosilicate aka pyrex. COE33. I have the appropriate torch and
> fuel/oxygen.
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> Of Sean Breheny
> Sent: Tuesday, October 31, 2017 2:05 PM
> To: Microcontroller discussion list - Public.
> Subject: RE: [EE] Vacuum plumbing
>
> What type of glass are you working with? You will need to actually melt
> it, not just soften it. This will likely take an oxy-fuel torch -
> especially if you are using Pyrex (and non-pyrex tends to crack when
> cooling so it isn't easier)
>
> On Oct 31, 2017 2:45 PM, "Van Horn, David" < david.vanhorn@
> backcountryaccess.com> wrote:
>
> > I discovered a source of valves, Kontes high vacuum similar to part
> > number
> > 826500-0004
> > Not cheap, but less expensive on Ebay.
> >
> > Now I need to find some writing on how to put the plumbing together.
> > The basics I know, but it's the "how do you hold all this in position
> > while flaming the tubes" part that has me wondering.
> >
> > --
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[Sean Breheny]

I know that "pyrex" cooking ware in the US is not borosilicate glass but
actual Pyrex-branded lab glassware made by Corning is borosilicate. I'm
using pyrex as a genericized trademark for the real deal.

I've done some sealing of volatile liquids (elemental Bromine) in pyrex
ampoules and I found it very challenging to get a technique down. If I used
propylene gas plus air (a.k.a. MAP-Pro gas) I could make it very soft but
there was always at least a microscopic leak channel which I attributed to
the inner walls of the tube never fusing together. Then I switched to
propylene plus pure oxygen, could melt pyrex to a true liquid, and I was
able to get rid of the tiny capillary leak channel but then I found that
the contents of the tube tended to expand during the sealing process (due
to getting hot) and my seal would always develop a bubble in the glass
before it was cool enough to solidify. This bubble would usually burst,
making a huge leak.

My next step was to pre-heat the gas in the headspace of the ampoule and
then begin sealing the end. When I got the timing right, this would create
suction because the air inside would contract as it cooled. Then I had the
opposite problem - the seal collapsing inward, or sometimes my pre-heating
would damage the sample inside. I still consider it a work in progress. My
best examples so far leak at a rate of about 1 milligram per week for an
ampoule containing 10g of Bromine (which has a significant vapor pressure -
around 1/3rd of an atmosphere at room temp) I can produce a beautiful seal
on one end of a tube which is open on the other end - it's the last seal
which closes off the tube that I find difficult.

Curiously, the few references I've found to how to seal ampoules don't seem
to hint at these problems. This includes 100-year-old hand-illustrated lab
glassblowing manuals. So I can sympathize with David's trouble obtaining
good practical info on doing this. AND I wasn't even trying to seal under
inert gas or vacuum. I suspect that most professionals who do ampoule
sealing today use liquid nitrogen to condense and/or freeze the contents
and keep them cooler than ambient even while the end is being sealed.

Sean


On Tue, Oct 31, 2017 at 6:22 PM, mike brown <***@n5qmg.com> wrote:

> Anything labeled pyrex is soda-lime glass, you surely mean PYREX. Not
> really sure where Pyrex stands right now.
>
> On Oct 31, 2017 16:03, "Van Horn, David" <
> ***@backcountryaccess.com> wrote:
>
> > Borosilicate aka pyrex. COE33. I have the appropriate torch and
> > fuel/oxygen.
> >
> > -----Original Message-----
> > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> > Of Sean Breheny
> > Sent: Tuesday, October 31, 2017 2:05 PM
> > To: Microcontroller discussion list - Public.
> > Subject: RE: [EE] Vacuum plumbing
> >
> > What type of glass are you working with? You will need to actually melt
> > it, not just soften it. This will likely take an oxy-fuel torch -
> > especially if you are using Pyrex (and non-pyrex tends to crack when
> > cooling so it isn't easier)
> >
> > On Oct 31, 2017 2:45 PM, "Van Horn, David" < david.vanhorn@
> > backcountryaccess.com> wrote:
> >
> > > I discovered a source of valves, Kontes high vacuum similar to part
> > > number
> > > 826500-0004
> > > Not cheap, but less expensive on Ebay.
> > >
> > > Now I need to find some writing on how to put the plumbing together.
> > > The basics I know, but it's the "how do you hold all this in position
> > > while flaming the tubes" part that has me wondering.
> > >
> > > --
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[Van Horn, David]

Here's the secret: Once you get it soft, twist and swirl. This breaks up the leak channel into tiny bubbles.
After flame cutting, pull off any excess with stainless steel tweezers and then torch it smooth.

I've got that technique down cold, and have done hundreds of such seals without problems, even when running at 50 microns inside.
Cooler torches help slow things down, a regular propane torch will work.


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[Sean Breheny]

What do you mean by "swirl"? I have tried twisting but it always seems to
just make the leak channel a twisted path but not fused together. Also,
twisting and pulling leads to a very tiny, brittle end to the seal. I was
able to make it "ball up" a little but never become robust enough that I
was comfortable it wouldn't break easily.

On Wed, Nov 1, 2017 at 12:43 PM, Van Horn, David <
***@backcountryaccess.com> wrote:

>
> Here's the secret: Once you get it soft, twist and swirl. This breaks up
> the leak channel into tiny bubbles.
> After flame cutting, pull off any excess with stainless steel tweezers and
> then torch it smooth.
>
> I've got that technique down cold, and have done hundreds of such seals
> without problems, even when running at 50 microns inside.
> Cooler torches help slow things down, a regular propane torch will work.
>
>
> --
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[Van Horn, David]

Swirl: Rotate the work around an origin outside it's diameter without twisting the work around it's centerline.
Think "dairy queen ice cream cone top" but sideways.

After this the end will look a bit rough, but after removing excess glass with tweezers, continue torching it starting at the tip and it will contract into a ball.
Alternatively for a less pretty but still effective seal, mash it with a marver.
The vac seal was made when you gathered the glass and then did the twist and swirl. This last bit is just appearance/fragility.

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Sean Breheny
Sent: Wednesday, November 1, 2017 12:14 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Vacuum plumbing

What do you mean by "swirl"? I have tried twisting but it always seems to just make the leak channel a twisted path but not fused together. Also, twisting and pulling leads to a very tiny, brittle end to the seal. I was able to make it "ball up" a little but never become robust enough that I was comfortable it wouldn't break easily.

On Wed, Nov 1, 2017 at 12:43 PM, Van Horn, David < ***@backcountryaccess.com> wrote:

>
> Here's the secret: Once you get it soft, twist and swirl. This
> breaks up the leak channel into tiny bubbles.
> After flame cutting, pull off any excess with stainless steel tweezers
> and then torch it smooth.
>
> I've got that technique down cold, and have done hundreds of such
> seals without problems, even when running at 50 microns inside.
> Cooler torches help slow things down, a regular propane torch will work.
>
>
> --
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[Sean Breheny]

Thanks, David. I'll try your technique when I get a chance.

Did you learn this by just trying or are you in to other glassblowing?

Have you seen the Youtube channel of Ross North?
https://www.youtube.com/watch?v=fPm9IZ1eWoI

Sean


On Wed, Nov 1, 2017 at 2:29 PM, Van Horn, David <
***@backcountryaccess.com> wrote:

> Swirl: Rotate the work around an origin outside it's diameter without
> twisting the work around it's centerline.
> Think "dairy queen ice cream cone top" but sideways.
>
> After this the end will look a bit rough, but after removing excess glass
> with tweezers, continue torching it starting at the tip and it will
> contract into a ball.
> Alternatively for a less pretty but still effective seal, mash it with a
> marver.
> The vac seal was made when you gathered the glass and then did the twist
> and swirl. This last bit is just appearance/fragility.
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> Of Sean Breheny
> Sent: Wednesday, November 1, 2017 12:14 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Vacuum plumbing
>
> What do you mean by "swirl"? I have tried twisting but it always seems to
> just make the leak channel a twisted path but not fused together. Also,
> twisting and pulling leads to a very tiny, brittle end to the seal. I was
> able to make it "ball up" a little but never become robust enough that I
> was comfortable it wouldn't break easily.
>
> On Wed, Nov 1, 2017 at 12:43 PM, Van Horn, David < david.vanhorn@
> backcountryaccess.com> wrote:
>
> >
> > Here's the secret: Once you get it soft, twist and swirl. This
> > breaks up the leak channel into tiny bubbles.
> > After flame cutting, pull off any excess with stainless steel tweezers
> > and then torch it smooth.
> >
> > I've got that technique down cold, and have done hundreds of such
> > seals without problems, even when running at 50 microns inside.
> > Cooler torches help slow things down, a regular propane torch will work.
> >
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
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[Van Horn, David]

I've been doing glass for a couple years now. Making a little side money and having fun.

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[William Westfield]

> I've done some sealing of volatile liquids (elemental Bromine) in pyrex ampoules and I found it very challenging to get a technique down.

I would imagine that the issues with sealing evacuated glassware are somewhat different than sealing an ampoule with contents at or above 1Atm. In the vacuum case, you have atmospheric pressure on your side…

BillW


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[Van Horn, David]

With sealing under pressure, I'd be looking for ways to drop the internal pressure, thermally or by pump or ??.
You probably could do a seal under light positive internal pressure, but I think it wouldn't be pretty.


-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of William Westfield
Sent: Wednesday, November 1, 2017 7:35 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Vacuum plumbing


> I've done some sealing of volatile liquids (elemental Bromine) in pyrex ampoules and I found it very challenging to get a technique down.

I would imagine that the issues with sealing evacuated glassware are somewhat different than sealing an ampoule with contents at or above 1Atm. In the vacuum case, you have atmospheric pressure on your side...

BillW


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[Van Horn, David]

I still wish I could find a book/document/etc that describes the building of a vacuum system for the range of 1 torr to 10 microns or so.
Seems to be a black art.


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[a***@stfc.ac.uk]

> I still wish I could find a book/document/etc that describes the building of a
> vacuum system for the range of 1 torr to 10 microns or so.
> Seems to be a black art.

Judging by the difficulties a program I am working on is having sealing helium over a temperature range, it is very much a black art.

Thankfully I'm only involved in the electricals ...



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[Van Horn, David]

Fortunately my only use for helium is as a rinse gas. Vac the system, fill with He, then vac it again, and call it clean. :)

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of ***@stfc.ac.uk
Sent: Friday, November 3, 2017 3:30 AM
To: ***@mit.edu
Subject: RE: [EE] Vacuum plumbing

> I still wish I could find a book/document/etc that describes the
> building of a vacuum system for the range of 1 torr to 10 microns or so.
> Seems to be a black art.

Judging by the difficulties a program I am working on is having sealing helium over a temperature range, it is very much a black art.

Thankfully I'm only involved in the electricals ...



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[Sean Breheny]

Is there any reason you don't use argon as your rinse gas? It's much
cheaper.

On Fri, Nov 3, 2017 at 11:15 AM, Van Horn, David <
***@backcountryaccess.com> wrote:

> Fortunately my only use for helium is as a rinse gas. Vac the system,
> fill with He, then vac it again, and call it clean. :)
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> Of ***@stfc.ac.uk
> Sent: Friday, November 3, 2017 3:30 AM
> To: ***@mit.edu
> Subject: RE: [EE] Vacuum plumbing
>
> > I still wish I could find a book/document/etc that describes the
> > building of a vacuum system for the range of 1 torr to 10 microns or so.
> > Seems to be a black art.
>
> Judging by the difficulties a program I am working on is having sealing
> helium over a temperature range, it is very much a black art.
>
> Thankfully I'm only involved in the electricals ...
>
>
>
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[Van Horn, David]

I have local sources for helium balloons that use actual helium, not "balloon gas" so I pay about $1 for 2 or so liters of gas in a convenient disposable container.
I don't need pressure, I'm always pulling the gas anyway.
My Neon and Argon come in glass flasks for $70/2l
Still working on a cost effective source for Xenon.

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Sean Breheny
Sent: Friday, November 3, 2017 10:02 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Vacuum plumbing

Is there any reason you don't use argon as your rinse gas? It's much cheaper.

On Fri, Nov 3, 2017 at 11:15 AM, Van Horn, David < ***@backcountryaccess.com> wrote:

> Fortunately my only use for helium is as a rinse gas. Vac the system,
> fill with He, then vac it again, and call it clean. :)
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
> Behalf Of ***@stfc.ac.uk
> Sent: Friday, November 3, 2017 3:30 AM
> To: ***@mit.edu
> Subject: RE: [EE] Vacuum plumbing
>
> > I still wish I could find a book/document/etc that describes the
> > building of a vacuum system for the range of 1 torr to 10 microns or so.
> > Seems to be a black art.
>
> Judging by the difficulties a program I am working on is having
> sealing helium over a temperature range, it is very much a black art.
>
> Thankfully I'm only involved in the electricals ...
>
>
>
> --
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[Sean Breheny]

Hmm, I wasn't aware that balloons used lower grade helium (in fact, based
on a quick Google search, it seems like they usually use the same grade as
is used for welding shielding gas, which is grade 5 (99.999%))

I don't think there is an inexpensive source of Krypton or Xenon. The
source for those gasses is the same as argon (fractional distillation of
ordinary air) and the abundance of Kr and Xe in air is extremely small,
whereas Ar is almost 1%.

I bought an aluminum 2200psi, I think 40 cubic foot (at STP) cylinder of
ultra-pure Argon for about $130 at my local welding supply two years ago. I
still have half of it. Most of that cost was the cylinder and valve. I
think a refill would be about $40. I had to purchase a regulator
separately. It is eventually going to be used to seal alkali metals
(sodium, potassium) in ampoules under inert gas. So far the only thing I
have done with it, which ended up using about half of the tank, was to do
an experiment to measure the density of Argon (I got a result which was
only a few percent off of the textbook value). It was good practice using
the flow-rate regulator, too.

Even if you don't need pressure I would think that standard high pressure
tanks would be the most cost effective for you because of the quantity they
can hold in a compact space. I chose to buy the tank but you can also rent
them for much less.

Sean


On Fri, Nov 3, 2017 at 12:13 PM, Van Horn, David <
***@backcountryaccess.com> wrote:

> I have local sources for helium balloons that use actual helium, not
> "balloon gas" so I pay about $1 for 2 or so liters of gas in a convenient
> disposable container.
> I don't need pressure, I'm always pulling the gas anyway.
> My Neon and Argon come in glass flasks for $70/2l
> Still working on a cost effective source for Xenon.
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> Of Sean Breheny
> Sent: Friday, November 3, 2017 10:02 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Vacuum plumbing
>
> Is there any reason you don't use argon as your rinse gas? It's much
> cheaper.
>
> On Fri, Nov 3, 2017 at 11:15 AM, Van Horn, David < david.vanhorn@
> backcountryaccess.com> wrote:
>
> > Fortunately my only use for helium is as a rinse gas. Vac the system,
> > fill with He, then vac it again, and call it clean. :)
> >
> > -----Original Message-----
> > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
> > Behalf Of ***@stfc.ac.uk
> > Sent: Friday, November 3, 2017 3:30 AM
> > To: ***@mit.edu
> > Subject: RE: [EE] Vacuum plumbing
> >
> > > I still wish I could find a book/document/etc that describes the
> > > building of a vacuum system for the range of 1 torr to 10 microns or
> so.
> > > Seems to be a black art.
> >
> > Judging by the difficulties a program I am working on is having
> > sealing helium over a temperature range, it is very much a black art.
> >
> > Thankfully I'm only involved in the electricals ...
> >
> >
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at http://mailman.mit.edu/
> > mailman/listinfo/piclist
> >
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[Denny Esterline]

As luck would have it, I just bought a welder for my shop and I still have
the receiving paperwork on my desk....
In Tucson AZ, USA. I bought two 125 cubic foot rated steel tanks for
$196.10 US each.
One filled with 75% Argon, 25% CO2 - the gas cost an additional $19.23 and
the other filled with "pure" argon which cost an additional $17.89
As this is sold as welding shield gas, I'm going to assume "pure" is about
99.999%.


Man, I really need to clean off my desk.

-Denny


On Fri, Nov 3, 2017 at 12:15 PM, Sean Breheny <***@cornell.edu> wrote:

> Hmm, I wasn't aware that balloons used lower grade helium (in fact, based
> on a quick Google search, it seems like they usually use the same grade as
> is used for welding shielding gas, which is grade 5 (99.999%))
>
> I don't think there is an inexpensive source of Krypton or Xenon. The
> source for those gasses is the same as argon (fractional distillation of
> ordinary air) and the abundance of Kr and Xe in air is extremely small,
> whereas Ar is almost 1%.
>
> I bought an aluminum 2200psi, I think 40 cubic foot (at STP) cylinder of
> ultra-pure Argon for about $130 at my local welding supply two years ago. I
> still have half of it. Most of that cost was the cylinder and valve. I
> think a refill would be about $40. I had to purchase a regulator
> separately. It is eventually going to be used to seal alkali metals
> (sodium, potassium) in ampoules under inert gas. So far the only thing I
> have done with it, which ended up using about half of the tank, was to do
> an experiment to measure the density of Argon (I got a result which was
> only a few percent off of the textbook value). It was good practice using
> the flow-rate regulator, too.
>
> Even if you don't need pressure I would think that standard high pressure
> tanks would be the most cost effective for you because of the quantity they
> can hold in a compact space. I chose to buy the tank but you can also rent
> them for much less.
>
> Sean
>
>
> On Fri, Nov 3, 2017 at 12:13 PM, Van Horn, David <
> ***@backcountryaccess.com> wrote:
>
> > I have local sources for helium balloons that use actual helium, not
> > "balloon gas" so I pay about $1 for 2 or so liters of gas in a convenient
> > disposable container.
> > I don't need pressure, I'm always pulling the gas anyway.
> > My Neon and Argon come in glass flasks for $70/2l
> > Still working on a cost effective source for Xenon.
> >
> > -----Original Message-----
> > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> > Of Sean Breheny
> > Sent: Friday, November 3, 2017 10:02 AM
> > To: Microcontroller discussion list - Public.
> > Subject: Re: [EE] Vacuum plumbing
> >
> > Is there any reason you don't use argon as your rinse gas? It's much
> > cheaper.
> >
> > On Fri, Nov 3, 2017 at 11:15 AM, Van Horn, David < david.vanhorn@
> > backcountryaccess.com> wrote:
> >
> > > Fortunately my only use for helium is as a rinse gas. Vac the system,
> > > fill with He, then vac it again, and call it clean. :)
> > >
> > > -----Original Message-----
> > > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
> > > Behalf Of ***@stfc.ac.uk
> > > Sent: Friday, November 3, 2017 3:30 AM
> > > To: ***@mit.edu
> > > Subject: RE: [EE] Vacuum plumbing
> > >
> > > > I still wish I could find a book/document/etc that describes the
> > > > building of a vacuum system for the range of 1 torr to 10 microns or
> > so.
> > > > Seems to be a black art.
> > >
> > > Judging by the difficulties a program I am working on is having
> > > sealing helium over a temperature range, it is very much a black art.
> > >
> > > Thankfully I'm only involved in the electricals ...
> > >
> > >
> > >
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[John Gardner]

If you buy a tank you need to be aware of the manufacturing date.

Theoretically you can get them re-certified, for about 3X the cost

of replacing the cylinder...

Last time I looked, anyway - It's been awhile.

On 11/3/17, Denny Esterline <***@gmail.com> wrote:
> As luck would have it, I just bought a welder for my shop and I still have
> the receiving paperwork on my desk....
> In Tucson AZ, USA. I bought two 125 cubic foot rated steel tanks for
> $196.10 US each.
> One filled with 75% Argon, 25% CO2 - the gas cost an additional $19.23 and
> the other filled with "pure" argon which cost an additional $17.89
> As this is sold as welding shield gas, I'm going to assume "pure" is about
> 99.999%.
>
>
> Man, I really need to clean off my desk.
>
> -Denny
>
>
> On Fri, Nov 3, 2017 at 12:15 PM, Sean Breheny <***@cornell.edu> wrote:
>
>> Hmm, I wasn't aware that balloons used lower grade helium (in fact, based
>> on a quick Google search, it seems like they usually use the same grade
>> as
>> is used for welding shielding gas, which is grade 5 (99.999%))
>>
>> I don't think there is an inexpensive source of Krypton or Xenon. The
>> source for those gasses is the same as argon (fractional distillation of
>> ordinary air) and the abundance of Kr and Xe in air is extremely small,
>> whereas Ar is almost 1%.
>>
>> I bought an aluminum 2200psi, I think 40 cubic foot (at STP) cylinder of
>> ultra-pure Argon for about $130 at my local welding supply two years ago.
>> I
>> still have half of it. Most of that cost was the cylinder and valve. I
>> think a refill would be about $40. I had to purchase a regulator
>> separately. It is eventually going to be used to seal alkali metals
>> (sodium, potassium) in ampoules under inert gas. So far the only thing I
>> have done with it, which ended up using about half of the tank, was to do
>> an experiment to measure the density of Argon (I got a result which was
>> only a few percent off of the textbook value). It was good practice using
>> the flow-rate regulator, too.
>>
>> Even if you don't need pressure I would think that standard high pressure
>> tanks would be the most cost effective for you because of the quantity
>> they
>> can hold in a compact space. I chose to buy the tank but you can also
>> rent
>> them for much less.
>>
>> Sean
>>
>>
>> On Fri, Nov 3, 2017 at 12:13 PM, Van Horn, David <
>> ***@backcountryaccess.com> wrote:
>>
>> > I have local sources for helium balloons that use actual helium, not
>> > "balloon gas" so I pay about $1 for 2 or so liters of gas in a
>> > convenient
>> > disposable container.
>> > I don't need pressure, I'm always pulling the gas anyway.
>> > My Neon and Argon come in glass flasks for $70/2l
>> > Still working on a cost effective source for Xenon.
>> >
>> > -----Original Message-----
>> > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
>> > Behalf
>> > Of Sean Breheny
>> > Sent: Friday, November 3, 2017 10:02 AM
>> > To: Microcontroller discussion list - Public.
>> > Subject: Re: [EE] Vacuum plumbing
>> >
>> > Is there any reason you don't use argon as your rinse gas? It's much
>> > cheaper.
>> >
>> > On Fri, Nov 3, 2017 at 11:15 AM, Van Horn, David < david.vanhorn@
>> > backcountryaccess.com> wrote:
>> >
>> > > Fortunately my only use for helium is as a rinse gas. Vac the
>> > > system,
>> > > fill with He, then vac it again, and call it clean. :)
>> > >
>> > > -----Original Message-----
>> > > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
>> > > Behalf Of ***@stfc.ac.uk
>> > > Sent: Friday, November 3, 2017 3:30 AM
>> > > To: ***@mit.edu
>> > > Subject: RE: [EE] Vacuum plumbing
>> > >
>> > > > I still wish I could find a book/document/etc that describes the
>> > > > building of a vacuum system for the range of 1 torr to 10 microns
>> > > > or
>> > so.
>> > > > Seems to be a black art.
>> > >
>> > > Judging by the difficulties a program I am working on is having
>> > > sealing helium over a temperature range, it is very much a black art.
>> > >
>> > > Thankfully I'm only involved in the electricals ...
>> > >
>> > >
>> > >
>> > > --
>> > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
>> > > View/change your membership options at http://mailman.mit.edu/
>> > > mailman/listinfo/piclist
>> > >
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>> > > View/change your membership options at
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[Bob Blick]

It works differently depending on which mob is running the gases mafia in your area. Where I live, only one size is "customer owned", all others are rentals and have collars with a name on it. There is no refilling. You swap tanks at the gas supply house. If your tank has expired, swap it at the same place you got it, no extra charge for recertification. Rental tanks must always be swapped at the named supplier, of course.

My "customer owned" argon tank costs under $70 to swap ($45 + taxes and fees). I forget the size, probably 120 to 160 ft^3, it's about 5 ft tall with its cap on and 9 inches diameter. I could probably shop around and get a better price but I'm not a big customer so I go to the place that is nicest to me.

CO2 is another story, it's cheap and easy to swap since both the beverage and marijuana supply places service CO2 as well as the welding supply.

Friendly regards,

Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of John Gardner
Sent: Friday, November 3, 2017 1:37 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Vacuum plumbing

If you buy a tank you need to be aware of the manufacturing date.

Theoretically you can get them re-certified, for about 3X the cost

of replacing the cylinder...

Last time I looked, anyway - It's been awhile.

On 11/3/17, Denny Esterline wrote:
> As luck would have it, I just bought a welder for my shop and I still have
> the receiving paperwork on my desk....
> In Tucson AZ, USA. I bought two 125 cubic foot rated steel tanks for
> $196.10 US each.
> One filled with 75% Argon, 25% CO2 - the gas cost an additional $19.23 and
> the other filled with "pure" argon which cost an additional $17.89
> As this is sold as welding shield gas, I'm going to assume "pure" is about
> 99.999%.
>
>
> Man, I really need to clean off my desk.
>
> -Denny

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[John Gardner]

...It works differently...

! You don't live in California, by any chance, do you, Bob? "8)

On 11/3/17, Bob Blick <***@outlook.com> wrote:
> It works differently depending on which mob is running the gases mafia in
> your area. Where I live, only one size is "customer owned", all others are
> rentals and have collars with a name on it. There is no refilling. You swap
> tanks at the gas supply house. If your tank has expired, swap it at the same
> place you got it, no extra charge for recertification. Rental tanks must
> always be swapped at the named supplier, of course.
>
> My "customer owned" argon tank costs under $70 to swap ($45 + taxes and
> fees). I forget the size, probably 120 to 160 ft^3, it's about 5 ft tall
> with its cap on and 9 inches diameter. I could probably shop around and get
> a better price but I'm not a big customer so I go to the place that is
> nicest to me.
>
> CO2 is another story, it's cheap and easy to swap since both the beverage
> and marijuana supply places service CO2 as well as the welding supply.
>
> Friendly regards,
>
> Bob
>
> ________________________________________
> From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of John
> Gardner
> Sent: Friday, November 3, 2017 1:37 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Vacuum plumbing
>
> If you buy a tank you need to be aware of the manufacturing date.
>
> Theoretically you can get them re-certified, for about 3X the cost
>
> of replacing the cylinder...
>
> Last time I looked, anyway - It's been awhile.
>
> On 11/3/17, Denny Esterline wrote:
>> As luck would have it, I just bought a welder for my shop and I still
>> have
>> the receiving paperwork on my desk....
>> In Tucson AZ, USA. I bought two 125 cubic foot rated steel tanks for
>> $196.10 US each.
>> One filled with 75% Argon, 25% CO2 - the gas cost an additional $19.23
>> and
>> the other filled with "pure" argon which cost an additional $17.89
>> As this is sold as welding shield gas, I'm going to assume "pure" is
>> about
>> 99.999%.
>>
>>
>> Man, I really need to clean off my desk.
>>
>> -Denny
>
> --
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[Sean Breheny]

The tank I bought was used and it will indeed need to be hydrotested before
the next filling (it's about 5 years old and the testing interval for
aluminum is shorter). However, my understanding from talking with the
welding supply place is that they have the equipment in-house to hydrotest
them and it doesn't increase the cost of refilling much. I don't recall
whether there is an option to swap if you own the tank. I bought it instead
of rented because I didn't want to be tied to the one shop because I do not
use much Argon and it will always be several years between re-fillings.

I also bought an oxygen cylinder from them but that one is steel and almost
brand new. The steel ones have 10 or 15 year test intervals (I can't recall
which mine is). I haven't had to refill either one yet. Got the O2 in 2014
and the Ar in 2015.

Sean


On Fri, Nov 3, 2017 at 4:37 PM, John Gardner <***@gmail.com> wrote:

> If you buy a tank you need to be aware of the manufacturing date.
>
> Theoretically you can get them re-certified, for about 3X the cost
>
> of replacing the cylinder...
>
> Last time I looked, anyway - It's been awhile.
>
> On 11/3/17, Denny Esterline <***@gmail.com> wrote:
> > As luck would have it, I just bought a welder for my shop and I still
> have
> > the receiving paperwork on my desk....
> > In Tucson AZ, USA. I bought two 125 cubic foot rated steel tanks for
> > $196.10 US each.
> > One filled with 75% Argon, 25% CO2 - the gas cost an additional $19.23
> and
> > the other filled with "pure" argon which cost an additional $17.89
> > As this is sold as welding shield gas, I'm going to assume "pure" is
> about
> > 99.999%.
> >
> >
> > Man, I really need to clean off my desk.
> >
> > -Denny
> >
> >
> > On Fri, Nov 3, 2017 at 12:15 PM, Sean Breheny <***@cornell.edu> wrote:
> >
> >> Hmm, I wasn't aware that balloons used lower grade helium (in fact,
> based
> >> on a quick Google search, it seems like they usually use the same grade
> >> as
> >> is used for welding shielding gas, which is grade 5 (99.999%))
> >>
> >> I don't think there is an inexpensive source of Krypton or Xenon. The
> >> source for those gasses is the same as argon (fractional distillation of
> >> ordinary air) and the abundance of Kr and Xe in air is extremely small,
> >> whereas Ar is almost 1%.
> >>
> >> I bought an aluminum 2200psi, I think 40 cubic foot (at STP) cylinder of
> >> ultra-pure Argon for about $130 at my local welding supply two years
> ago.
> >> I
> >> still have half of it. Most of that cost was the cylinder and valve. I
> >> think a refill would be about $40. I had to purchase a regulator
> >> separately. It is eventually going to be used to seal alkali metals
> >> (sodium, potassium) in ampoules under inert gas. So far the only thing I
> >> have done with it, which ended up using about half of the tank, was to
> do
> >> an experiment to measure the density of Argon (I got a result which was
> >> only a few percent off of the textbook value). It was good practice
> using
> >> the flow-rate regulator, too.
> >>
> >> Even if you don't need pressure I would think that standard high
> pressure
> >> tanks would be the most cost effective for you because of the quantity
> >> they
> >> can hold in a compact space. I chose to buy the tank but you can also
> >> rent
> >> them for much less.
> >>
> >> Sean
> >>
> >>
> >> On Fri, Nov 3, 2017 at 12:13 PM, Van Horn, David <
> >> ***@backcountryaccess.com> wrote:
> >>
> >> > I have local sources for helium balloons that use actual helium, not
> >> > "balloon gas" so I pay about $1 for 2 or so liters of gas in a
> >> > convenient
> >> > disposable container.
> >> > I don't need pressure, I'm always pulling the gas anyway.
> >> > My Neon and Argon come in glass flasks for $70/2l
> >> > Still working on a cost effective source for Xenon.
> >> >
> >> > -----Original Message-----
> >> > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
> >> > Behalf
> >> > Of Sean Breheny
> >> > Sent: Friday, November 3, 2017 10:02 AM
> >> > To: Microcontroller discussion list - Public.
> >> > Subject: Re: [EE] Vacuum plumbing
> >> >
> >> > Is there any reason you don't use argon as your rinse gas? It's much
> >> > cheaper.
> >> >
> >> > On Fri, Nov 3, 2017 at 11:15 AM, Van Horn, David < david.vanhorn@
> >> > backcountryaccess.com> wrote:
> >> >
> >> > > Fortunately my only use for helium is as a rinse gas. Vac the
> >> > > system,
> >> > > fill with He, then vac it again, and call it clean. :)
> >> > >
> >> > > -----Original Message-----
> >> > > From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
> >> > > Behalf Of ***@stfc.ac.uk
> >> > > Sent: Friday, November 3, 2017 3:30 AM
> >> > > To: ***@mit.edu
> >> > > Subject: RE: [EE] Vacuum plumbing
> >> > >
> >> > > > I still wish I could find a book/document/etc that describes the
> >> > > > building of a vacuum system for the range of 1 torr to 10 microns
> >> > > > or
> >> > so.
> >> > > > Seems to be a black art.
> >> > >
> >> > > Judging by the difficulties a program I am working on is having
> >> > > sealing helium over a temperature range, it is very much a black
> art.
> >> > >
> >> > > Thankfully I'm only involved in the electricals ...
> >> > >
> >> > >
> >> > >
> >> > > --
> >> > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> >> > > View/change your membership options at http://mailman.mit.edu/
> >> > > mailman/listinfo/piclist
> >> > >
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> >> > > View/change your membership options at
> >> > > http://mailman.mit.edu/mailman/listinfo/piclist
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> >> > View/change your membership options at http://mailman.mit.edu/
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> >> >
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[RussellMc]

On 4 November 2017 at 14:25, Sean Breheny <***@cornell.edu> wrote:

> The tank I bought was used and it will indeed need to be hydrotested before
> the next filling (it's about 5 years old and the testing interval for
> aluminum is shorter).


​Tanks last indefinitely without hydrotesting if you don't refill them
The value of indefinitely varies but in all cases is definitely not
definite.​

For example:

Fortunately, LPG has quite a low vapour pressure in such applications.

http://bit.ly/zzlpg <- jpg ( best)

http://bit.ly/zzlpg2 <- jpg (I don't THINK the smoke is
coming from the bottles. :-) )

Ctrl - to or Ctrl-mouse_rolldown to shrink

________________

Album - the above two photos are at end - quickest access is click first
image and then click left side of image.

http://bit.ly/2xzJZIY
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[Sean Breheny]

Yikes, those rusty tanks are scary. However, as you point out, the vapor
pressure is at most 320 psi (pure propane at 55 deg C). That's considerably
less than 2200 psi :)

On Sat, Nov 4, 2017 at 7:14 AM, RussellMc <***@gmail.com> wrote:

> On 4 November 2017 at 14:25, Sean Breheny <***@cornell.edu> wrote:
>
> > The tank I bought was used and it will indeed need to be hydrotested
> before
> > the next filling (it's about 5 years old and the testing interval for
> > aluminum is shorter).
>
>
> ​Tanks last indefinitely without hydrotesting if you don't refill them
> The value of indefinitely varies but in all cases is definitely not
> definite.​
>
> For example:
>
> Fortunately, LPG has quite a low vapour pressure in such applications.
>
> http://bit.ly/zzlpg <- jpg ( best)
>
> http://bit.ly/zzlpg2 <- jpg (I don't THINK the smoke is
> coming from the bottles. :-) )
>
> Ctrl - to or Ctrl-mouse_rolldown to shrink
>
> ________________
>
> Album - the above two photos are at end - quickest access is click first
> image and then click left side of image.
>
> http://bit.ly/2xzJZIY
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[Van Horn, David]

The last of my supplies came in yesterday, so tonight I will be trying once again to get a relatively leak free manifold constructed.
Kontes High-Vac stopcocks, glass plumbing, limited use of Tygon flexible lines. The neon sign guys swear at Dow vacuum grease, but I think for my purposes it will be fine. I don't have metal electrodes in my pieces for it to react with, and I don't need to run the "bombarding" process which uses high current to bake out impurities.
If I have success in the manifold construction, then it will be time to break the seals on my Neon and Argon flasks.

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[a***@stfc.ac.uk]

>
> The last of my supplies came in yesterday, so tonight I will be trying once
> again to get a relatively leak free manifold constructed.
> Kontes High-Vac stopcocks, glass plumbing, limited use of Tygon flexible
> lines. The neon sign guys swear at Dow vacuum grease, but I think for my
> purposes it will be fine. I don't have metal electrodes in my pieces for it to
> react with, and I don't need to run the "bombarding" process which uses high
> current to bake out impurities.
> If I have success in the manifold construction, then it will be time to break the
> seals on my Neon and Argon flasks.
>

Ooh, it's getting exciting ... :)


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[Van Horn, David]

Ooh, it's getting exciting ... :)


Indeed. Breaking the seal is irreversible, and if I have leaks, I contaminate my flasks.
Like this one: https://www.ebay.com/i/332271376045?chn=ps&dispItem=1

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[Sean Breheny]

I still don't understand why you buy neon in that form. Seems really
expensive. You could get a compressed neon cylinder for about the same
price and I think similar purity, but the quantity would be 100x. I know
you don't want pressure but you can use a regulator to take it down to low
pressure.

On Wed, Nov 8, 2017 at 1:30 PM, Van Horn, David <
***@backcountryaccess.com> wrote:

>
> Ooh, it's getting exciting ... :)
>
>
> Indeed. Breaking the seal is irreversible, and if I have leaks, I
> contaminate my flasks.
> Like this one: https://www.ebay.com/i/332271376045?chn=ps&dispItem=1
>
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[Van Horn, David]

I still don't understand why you buy neon in that form. Seems really expensive. You could get a compressed neon cylinder for about the same price and I think similar purity, but the quantity would be 100x. I know you don't want pressure but you can use a regulator to take it down to low pressure.


So add storage of high pressure cylinder, plus needing regulator, then plumbing from regulator into gas system. Then add the hazard of accidental overpressure into the manifold system blowing things apart.

I could be talked into some sort of mylar bag temporary container, filled from the cylinder and then joined to the manifold.

A liter or so might be a year's supply for me.


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[RussellMc]

On 9 November 2017 at 07:30, Van Horn, David <
***@backcountryaccess.com> wrote:

>
> Indeed. Breaking the seal is irreversible, and if I have leaks, I
> contaminate my flasks.
> Like this one: https://www.ebay.com/i/332271376045?chn=ps&dispItem=1


This 'looks' to be better value. Maybe not.


https://www.ebay.com/itm/Neon-Gas-Research-Grade-99-999-pure/182886625910?hash=item2a94e47276:g:SI8AAOSwjDZYflRQ


Russell
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[graham foulkes]

On Fri, Nov 3, 2017 at 5:16 AM Van Horn, David <
***@backcountryaccess.com> wrote:

> Fortunately my only use for helium is as a rinse gas. Vac the system,
> fill with He, then vac it again, and call it clean. :)
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf
> Of ***@stfc.ac.uk
> Sent: Friday, November 3, 2017 3:30 AM
> To: ***@mit.edu
> Subject: RE: [EE] Vacuum plumbing
>
> > I still wish I could find a book/document/etc that describes the
> > building of a vacuum system for the range of 1 torr to 10 microns or so.
> > Seems to be a black art.
>
> Judging by the difficulties a program I am working on is having sealing
> helium over a temperature range, it is very much a black art.
>
> Thankfully I'm only involved in the electricals ...
>
>
> Hi. Removing occluded gases off the internal surfaces is not so simple.
> Heating and several purges maybe required to get rid of the last molecules
> of oxygen/ water vapor off the surfaces. Vacuum tube manufacturing in days
> of old required various techniques to eliminate occluded contaminants which
> would 'poison' the Cathode coating on the emission surface. Reactive
> metals, magnesium was used as a getter to mop up the remains of the oxygen
> out gassing during life of the tube . As an aside, the leak rate on the
> glass to metal pressed seal was absolutely leakproof using lower melting
> point uranium glass, now dumet wires with similar thermal characteristics
> are use.

On the subject of gas metering, we used a simple arraignment of two low
volume capacity solenoid valves with a short connection pipe in series to
sequentially pulse measured slugs of gas into a superplastic structure to
inflate at a precise rate and shape. The volumes transferred were quite
small and allowed the superplastic forming rate to be carefully controlled.
Was a YouTube a while back showing French engineer making his own trI ode
tubes




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[Van Horn, David]

>From scientific suppliers, it's 33 boro.

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of mike brown
Sent: Tuesday, October 31, 2017 4:22 PM
To: Microcontroller discussion list - Public.
Subject: RE: [EE] Vacuum plumbing

Anything labeled pyrex is soda-lime glass, you surely mean PYREX. Not really sure where Pyrex stands right now.

On Oct 31, 2017 16:03, "Van Horn, David" < ***@backcountryaccess.com> wrote:

> Borosilicate aka pyrex. COE33. I have the appropriate torch and
> fuel/oxygen.
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On
> Behalf Of Sean Breheny
> Sent: Tuesday, October 31, 2017 2:05 PM
> To: Microcontroller discussion list - Public.
> Subject: RE: [EE] Vacuum plumbing
>
> What type of glass are you working with? You will need to actually
> melt it, not just soften it. This will likely take an oxy-fuel torch -
> especially if you are using Pyrex (and non-pyrex tends to crack when
> cooling so it isn't easier)
>
> On Oct 31, 2017 2:45 PM, "Van Horn, David" < david.vanhorn@
> backcountryaccess.com> wrote:
>
> > I discovered a source of valves, Kontes high vacuum similar to part
> > number
> > 826500-0004
> > Not cheap, but less expensive on Ebay.
> >
> > Now I need to find some writing on how to put the plumbing together.
> > The basics I know, but it's the "how do you hold all this in
> > position while flaming the tubes" part that has me wondering.
> >
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[RussellMc]

1. ebay

Some of the lower cost valves (page 3) may be of use?


https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=high-vacuum+valve&_pgn=3&_skc=400&rt=nc


2. Interesting if not directly relevant :-)


DIY difusion pump

http://diyvacuumtubes.com/mini-diy-diffusion-pump-t12.html


DIY vacuum tubes.
*Suggests refrigeration valves may be of use*

http://tubecrafter.com/tubecrafter_012.htm


Russell
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