Sciencemadness Discussion Board

Ground glass quartz tube

plante1999 - 17-4-2013 at 13:02

Does anyone know where a tube, made of quartz and that have ground glass joint, is sold? A tube much like garage chemist one: http://www.sciencemadness.org/talk/viewthread.php?tid=10564

Thanks!

Mixell - 17-4-2013 at 13:07

They are usually done on demand, I'm also searching for one.

Mailinmypocket - 17-4-2013 at 13:14

Same here... I have a large quartz test tube but have had an impossibly difficult time finding a glass blower that does quartz/jointed connections. I've gotten by with cramming glass wool tightly between the quartz and boro glass but its far from practical :(

Lambda-Eyde - 17-4-2013 at 13:24

http://www.technicalglass.com/ - I'd estimate 25-40$ for a tube with a joint.

Edit: For a tube like GC uses in that thread, you'd obviously have to fork out more. Also keep in mind what he says about joints - a quartz female and a borosilicate male will crack!

[Edited on 17-4-2013 by Lambda-Eyde]

Magpie - 17-4-2013 at 14:03

Here's a supplier of quartz tubing. They will also do glassblowing and ground glass joints. It may take some coaxing for small jobs, however.

http://www.quartz.com/quartz.html

bahamuth - 17-4-2013 at 16:18

Quote: Originally posted by Lambda-Eyde  
Also keep in mind what he says about joints - a quartz female and a borosilicate male will crack!


Spherical joints will do the trick, joining borosilicate and quartz.



garage chemist - 17-4-2013 at 21:26

Even a quartz male and borosilicate female will crack- if they get hot and are left to cool while assembled. Such a combination must be disassembled while still hot to avoid cracking, as I found out.
Only spherical joints are truly safe for combining quartz and borosilicate, although you can get away with conical joints if you follow the advice I just gave.

Go to a university glassblower and ask whether he can make such a tube for you. Don't get put off by the price, I paid a bit more than EUR 100 for mine. Custom made glassware has its price.

Dr.Bob - 18-4-2013 at 06:36

The company below is a quartz specialist, and is in NC, so ever better (for me.) I would call them for a quote. They are smaller and might even work with individuals, but not sure.

Also, chemglass has made a few simple quartz items for me in the past, at reasonable prices.

http://prismresearchglass.com/

turd - 18-4-2013 at 11:30

Jeeez!

You are not talking about quartz. Fused silica a.k.a. fused quartz is - by definition - not quartz. Quartz glass is an oxymoron but acceptable. Quartz is wrong - and not a single person in this thread got it right. :(

Mixell - 18-4-2013 at 11:53

The usually acceptable term is fused quartz.
Fused silica usually refers to this type of items: http://www.ebay.com/itm/Melting-Crucible-for-Gold-Silver-Bra...

unionised - 18-4-2013 at 12:28

"Only spherical joints are truly safe for combining quartz and borosilicate,"
Why?

Hexavalent - 18-4-2013 at 12:30

Quote: Originally posted by unionised  
"Only spherical joints are truly safe for combining quartz and borosilicate,"
Why?


Perhaps due to differences in coefficients of expansion?

watson.fawkes - 18-4-2013 at 15:30

Quote: Originally posted by Hexavalent  
Perhaps due to differences in coefficients of expansion?
Yes. The thermal coefficients vary by a factor of six.

Spherical joints are the not only joint geometries that are possible, merely the most common and standard ones. Flanged joints, with gasket and retaining clamp, would work just as well.

turd - 20-4-2013 at 13:01

Quote: Originally posted by Mixell  
The usually acceptable term is fused quartz.
Fused silica usually refers to this type of items: http://www.ebay.com/itm/Melting-Crucible-for-Gold-Silver-Bra...

At least in the scientific literature that I'm aware of fused silica is generally translucent material used to make ampoules or other reaction containers. And nobody I know uses these opaque silica crucibles - it's mostly Al2O3 if oxides are OK.

The distinction between fused quartz and fused silica is a bit silly - after all quartz is a form of silica and chances are high that what you call fused silica is made from quartz sand. ;)

But all this is besides the point. The actual point is: whether you call it fused silica or fused quartz or quartz glass - it's bulk amorphous SiO2, whereas quartz designates a set of crystalline SiO2 polymorphs. So don't call your tubes quartz tubes, because every time you do god kills a kitten.

Mixell - 20-4-2013 at 13:18

Well, I'll need to in order to purchase some...

unionised - 20-4-2013 at 13:20

I know why you can't use a tapered joint with two different materials if their expansion coefficients don't match.
(and, incidentally, it's not the ratio of the expansions that matters so much as the difference)
What I'd like someone to explain is how a spherical (well, hemispherical really) joint will work any better.

They are useful in that you don't need to align them so carefully but, as far as I can tell, if the ball expands more than the socket then the socket will snap and if the socket expands more than the ball then the joint will leak.

[Edited on 20-4-13 by unionised]

turd - 21-4-2013 at 12:27

Quote: Originally posted by Mixell  
Well, I'll need to in order to purchase some...

???
I think I didn't get my point across:
"fused quartz tube" = good.
"quartz tube" = just wrong.
If a vendor uses the latter I would not trust him - he doesn't know what he's selling.

watson.fawkes - 21-4-2013 at 15:57

Quote: Originally posted by turd  
"fused quartz tube" = good.
"quartz tube" = just wrong.
If a vendor uses the latter I would not trust him - he doesn't know what he's selling.
Well, given that some old-line vendors aren't pedantic about repeated the word "fused" everywhere, I don't see why there such a need to be pedantic about it here. All these vendors say "fused quartz" sometimes and just "quartz" sometimes.
National Scientific Company, whose URL is quartz.com.
Precision Electronic Glass
GM Associates
These vendors all appear on the ASGS Buyer's Guide page (the ASGS is The American Scientific Glassblowers Society); it was a handy place from which to pull a number of examples.

Fleaker - 22-4-2013 at 13:43

I have about 300 quartz tubes that I bought and were the wrong size. They're 26X30 mm Heraeus (basically their version of GE214). Each is 1200 mm or so in length. $20/a piece.

plante1999 - 22-4-2013 at 14:18

Do you mean they are oval? Are they ground quartz(ground glass)?

Morgan - 22-4-2013 at 16:36

He means 2mm wall thickness. That's a lot of quartz tubing to buy and the wrong size. And I thought I bought a lot buying 3 boxes (15 per box) Heraeus quartz tubes just because they were cheap and I like materials science. Quartz has so many good qualities.

Mixell - 22-4-2013 at 16:50

The price is good, but it will probably be a hassle to ship.

unionised - 23-4-2013 at 13:08

I'd still like too know why Garage Chemist thinks spherical joints are OK with mis-matched expansion coefficients.

turd - 24-4-2013 at 04:49

Quote: Originally posted by watson.fawkes  
Well, given that some old-line vendors aren't pedantic about repeated the word "fused" everywhere, I don't see why there such a need to be pedantic about it here.

If it is pedantic not to designate things with words that have a completely different meaning then I will take it as a compliment. Also this must be one of the worst appeal to authority arguments ever. If at least you would have bothered to find something in the scientific literature. For me it is like calling hydrochloric acid "HCL": Do it once it's a typo, do it consistently you're an ignorant, be proud about your ignorance and you're a "kewl". Unfortunately the standard enforced in the organic chemistry subforum is not maintained for other topics.
Quote:
I'd still like too know why Garage Chemist thinks spherical joints are OK with mis-matched expansion coefficients.

I suppose the idea is that the force of expansion is not only exerted in transversal direction leading to wedging and consequently breaking but also in longitudinal direction leading to a sliding apart.

In any case I don't buy the problem. The real solution is to not heat the joints. I know a group that does *many* evacuated fused silica ampoules, the last part of a tube being molten ~2-5 cm from the joint. Due to the low thermal conductivity the only breaking of joints was during cleaning. And no, the remaining tubes are not removed while still hot. I've seen a few of these setups and never anything but conical joints. The fused silica is always male, of course.

The same people regularly do reactions in a fused silica tube in a tube furnace typically at 1100°C under vacuum, H2 and Ar and not once in several years a joint has broken. If your joints break you are doing something wrong or your glass is of bad quality.