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klugesmith

Tue Feb 12 2013, 11:43PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

Good to see you here, Carl. I applaud your example of using real name and picture.
Nice work with the plasma tubes. Would other people's work be welcome in this thread?

Here's an open question:
When gases are traded by volume, is that volume at STP (0Â° Celsius, 1 atm) or at some higher temperature (e.g. "Normal Temperature & Pressure")? I just spent 1/2 hour Googling without getting satisfaction. The answer might depend on the product and the market, e.g. a 0.9 liter flask of neon vs. a 3 billion cubic foot natural gas tanker.

It came up while reviewing the cost to fill the main propellant tank on Dawn spacecraft, now motoring from Vesta to Ceres. It was launched in 2007, carrying 425 kilograms of xenon. Back then, I figured that was most of US $1 million worth. Roughly 73000 liters at, say, $10/liter. Don't know the purity specification.
(Also figured that the Xe would be moderately supercritical; a fluid 60% denser than water and 3.3 x denser than ideal gas at MW=131, 30Â° C, 1310 psi. Xe is a convenient medium for investigations very close to the critical point.)

-Rich Feldman

bwsparxz

Wed Feb 13 2013, 12:11AM

Registered Member #1928 Joined: Mon Jan 12 2009, 01:51PM
Location: Reidsville, NC
Posts: 10

Hi Carl, Nice to see you here. Been following your work in Fusor forum. Beautiful work. Always been impressed with your glassblowing skills. Had a fascination with plasma display since I first saw a plasma ball. I keep mine that I 've had for many years always running. Your displays put it to shame.

macona

Wed Feb 13 2013, 03:00AM

Registered Member #3272 Joined: Mon Oct 04 2010, 11:40PM
Location: Beaverton, OR
Posts: 101

Conundrum wrote ...

Wonder if there is much xenon in an old linear flash tube from a few defunct ancient flash guns?

You wont get much. My plan is to use high pressure xenon arc lamps as a source. The lamps are usually pressurized to 400 to 500 PSI. I have a piece of 1.5" stainless tubing. One end has been capped off with plate and a VCR fitting, the other end is a standard 2-3/4" conflat flange. The idea is I will fill the pipe with as many lamps as I can fit in with a couple steel ball bearings. The end is sealed. On the VCR side I will install a filter and a shut off valve. Hook up the assembly to my RGA system and pump it down and bake it out for a couple days, it should get down to the -8 or -9 range. Seal it off and then whack it to break the lamps inside and release the xenon.

Not pure but a heck of a lot cheaper than other sources. Lamps are pretty cheap on ebay. Similar to this, but I often see them cheaper.

Carl A. Willis

Wed Feb 13 2013, 04:47AM

Registered Member #9640 Joined: Wed Jan 16 2013, 07:53AM
Location: Albuquerque, New Mexico
Posts: 26

@Wolfram: You have a nice vacuum system in the works. Per your request, I have added some additional photos of the gas handling / vacuum / processing equipment I use below. The upper photos all depict the gas cylinders, metal-sealed gas lines, regulators, etc.; the lower photos include the glassworking torches, annealing kiln, oxygen concentrator for the small torches, and the HV supply. Let me know if any of it merits further discussion.

@Rich: Happy birthday (I know a day or two late), and good to see you here. STP is implicit in the use of volume representations of gas quantity, so you are correct on that. Xenon in vast bulk quantities is probably a lot cheaper than the refined small quantities we buy. In fact, it would not surprise me if the material used on these space missions is less than 99%, what might be called crude in the industry but is certainly adequate for the intended application (the balance being krpyton). Definitely please share other projects!

@Brian: Good to see you here too!

@Macona: It's surely false economy to consider recovering xenon from arc lamps if the goal is any sort of serious involvement with the plasma displays. I'll take your word that it's cheap gas, but the expense comes in when you consider how to practically get it out and deliver it. All I can think of is a large vacuum vessel in which you can crack the envelope with a motion feedthrough, which is a lot of expense and difficulty to do right for the purpose of recovering a few bucks' worth of Xe. If you buy a refillable cylinder, your up-front costs are high, but the product AND the cylinder are essentially fungible, real assets. If you even entertain the idea of doing this stuff over a period of a couple years or more, even sporadically as I do, I think a cylinder is what you want.

-Carl

Scott Fusare

Wed Feb 13 2013, 12:18PM

Registered Member #531 Joined: Sat Feb 17 2007, 10:51AM
Location: Burlington, Vermont
Posts: 125

Carl A. Willis wrote ...

@Macona: It's surely false economy to consider recovering xenon from arc lamps if the goal is any sort of serious involvement with the plasma displays. I'll take your word that it's cheap gas, but the expense comes in when you consider how to practically get it out and deliver it. All I can think of is a large vacuum vessel in which you can crack the envelope with a motion feedthrough, which is a lot of expense and difficulty to do right for the purpose of recovering a few bucks' worth of Xe. If you buy a refillable cylinder, your up-front costs are high, but the product AND the cylinder are essentially fungible, real assets. If you even entertain the idea of doing this stuff over a period of a couple years or more, even sporadically as I do, I think a cylinder is what you want.

Interesting note: Bill Connery did successfully use this technique to recover and re-purpose Xenon. In his case I believe it was the cheap availability of surplussed mufti-kilowatt size Xe short arc lamps that made it practical. He used a setup not dissimilar to what Carl describes, sans motion feed-through.

Lacking the availability of cheap, large lamps the cylinder would most certainly be the way to go.

Ash Small

Wed Feb 13 2013, 03:41PM

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

I've found this information regarding working borosilicate glass, which may be useful to anyone attempting this:

"Critical Temperatures

150Â°C - When working above this temperature care should be taken to heat and cool Borosilicate glass in a slow and uniform manner.

500Â°C - The maximum temperature that Borosilicate glass should be subjected to and then only for short period of no longer than a few minutes.

510Â°C - Temperature at which thermal stress can be introduced to Borosilicate glassware.

565Â°C - Annealing temperature. When uniformly heated in controlled conditions, such as a kiln or oven thermal stressâ€™s can be removed.

820Â°C - Softening point at which Borosilicate may deform.

1252Â°C - Working point, the temperature that glassblowers need to attain in order to work Borosilicate glass."

I'm just wondering about safety precautions, as no mention has been made regarding safety, and there doesn't appear to be any clues in the photo's.

Am I to assume that goggles/safety glasses are sufficient, or or are plexi-glass screens, etc. recommended?

(I'm planning on just using argon/air, as that's all I have on hand at the moment, but I'll have to sort out a mekeshift kiln/oven for annealing before I start, unless I can find anyone locally who can anneal it for me.)

macona

Thu Feb 14 2013, 01:37AM

Registered Member #3272 Joined: Mon Oct 04 2010, 11:40PM
Location: Beaverton, OR
Posts: 101

Ash Small wrote ...

I'm just wondering about safety precautions, as no mention has been made regarding safety, and there doesn't appear to be any clues in the photo's.

Am I to assume that goggles/safety glasses are sufficient, or or are plexi-glass screens, etc. recommended?

You really need special glasses for glass working. They do a couple things, one is they get rid of the orange sulfur flare when working with the glass. Second, the are there to protect your eyes from infrared and UV light from working the glass. In the past cobalt or "didymium" glasses were used but the IR protection was pretty bad and you could develop cataracts from working with them. Modern glass working glasses are safe. These glasses can also be used for torch welding aluminum.

A friend bought a pair a few years ago but I cant find the site, I believe the lenses are referred to as "ACE". The filter out the UV, IR and the sodium flare.

Edit: Found the company, they make some real nice stuff and cheaper than a lot of other companies.

Ash Small

Thu Feb 14 2013, 01:59AM

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

Thanks Macona, I found a link here:

I'm thinking of trying to use a carbon arc flame (I have one somewhere), as I don't currently have access to an oxy-propane torch (I've plenty of O2, but will need to pick up a torch and some propane).

I'll need to use a welding mask with it which blocks out UV anyway (polycarbonate safety glasses also block UV, by the way), but I imagine they'll also block IR, but I'm not sure if they will block sodium flare. I'm not sure if visibility will be sufficient for working glass, but it may be.

EDIT: I've worked with glass bottle machines for several different companies, and the only protection we were provided with was poltcarbonate safety glasses that block UV.

zrg

Thu Feb 14 2013, 08:59AM

Registered Member #4762 Joined: Sun May 06 2012, 05:59PM
Location: Russia
Posts: 93

Are you sure that green color of Xe is produced because of air traces? None of my experiments proved that; however I got intense green color of different tints when mixed xenon with organic compounds. Did you wash the flasks before evacuating and did you pre-heat them under vacuum?
How do you exactly add air to the greenish xenon flasks? Can it come through the vacuum grease often used to cover o-rings and similar viton/rubber items in the system?

macona

Thu Feb 14 2013, 09:27AM

Registered Member #3272 Joined: Mon Oct 04 2010, 11:40PM
Location: Beaverton, OR
Posts: 101

Ash Small wrote ...

Thanks Macona, I found a link here:

I would not even think about using carbon arc to do something like this. That is a bad idea on so many fronts. First is the massive, I mean MASSIVE amounts of UV emitted. It is not just goggles you need, it is a full set of leathers. Next is the amount of light, the welding lenses would make it virtually impossible to see the color of the glass which gives visual clues of it's temperature. Lastly, a carbon arc is very difficult to direct and often you need a pinpoint flame.

Get a used oxy-acet set off crags list or something. Replace the hoses with type T if they are not and get a standard BBQ tank of propane. The acer regulator will connect and work just fine. I have a Victor J50 for small stuff as well as a couple bench torches. Paid $5 for the old Welch and got the small one in a lot of stuff at an auction:

Sargent Welch bench torch by macona, on Flickr

Fischer multi flame burner by macona, on Flickr

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