Sciencemadness Discussion Board - ground glass, help please

ground glass, help please

Pyro - 23-5-2012 at 09:55

hi,
I live in europe, and european ground glass is by a different standard than the rest of the world.
over here the sizes are like this:NS 10, NS12, NS14, NS19, NS24, NS29, NS32, NS45 and NS60
NS stands for normschliff.
does anyone know what interational size (xx/xx) fits NS?(preferably NS29)
thank you,
alex

Lambda-Eyde - 23-5-2012 at 10:58

A NS29 (or 29/32) will fit a US 29/42. A NS24 fits a 24/40, NS14 fits 14/20 and so on.

Dr.Bob - 23-5-2012 at 11:25

The standard US sizes are 10/18 or 10/30, 14/20, 19/22 (also 19/38), 24/40, 29/42, 32/45, and 45/50. I think the first number should match your NS# to be a fit, so that would be 29/42 for NS29.

There are also shorter versions of most of those, like 24/29, 19/22, and one for 29/32.

See http://en.wikipedia.org/wiki/Ground_glass_joint for more info.

Pyro - 23-5-2012 at 12:09

oooh, ok. thanks guys, i only seemed to get the wiki page in german lol, and when i changed to wiki in english i only got a very small one

now i can order from laboy. or if still possible from dr bob.

Endimion17 - 23-5-2012 at 14:06

Actually, the European standard is pretty much the international, world standard. It's the US standard that's somewhat unique, for some weird reason. Therefore, don't buy US glassware as you'll have trouble connecting stuff. These things are quite expensive so mistakes will cost you a lot.
The names of the joints are often shortened, therefore NS24 means NS 24/29, NS29 means NS 29/32, etc.

AFAIK, these are the joints used:
7/16
10/19
12/21
14.5/23 (AKA 14/23 or NS14)
19/26
24/29
29/32
34/35
45/40
60/46
(smaller and larger joints are quite uncommon, though laboratory flameworkers are able to make them if needed)

NS14, NS19, NS24 and NS29 are the most common. Larger ones are usually found on Soxhlet apparatus, and the smaller ones on volumetric flasks.

Pyro - 23-5-2012 at 14:18

my ''style'' is NS29, i got a bunch of equipment with NS29, NS14 is for thermometer inserts.
but what is the meaning of that eccentric joint system? NS seems so much less complex
thanks.

Endimion17 - 23-5-2012 at 17:09

Quote: Originally posted by Pyro

my ''style'' is NS29, i got a bunch of equipment with NS29, NS14 is for thermometer inserts.
but what is the meaning of that eccentric joint system? NS seems so much less complex
thanks.

NS29 is fine enough. It's about the largest comfortable joint for most applications.
What do you mean by eccentric joint system? Modern international and US system do fit together, but their lengths are not the same, therefore most, if not all holding clips are unusable.

BTW, how are different "kids" of joints called in German? I understand what normschliff means as we use the schliff word in Croatia. How do you call "female" and "male" joints?
We call it, loosely translated to English, a "slot" (ležište) and a "core" (jezgra). For example, a female NS14 joint, we say NB-L (14/23), and for a male NS29 we say NB-J (29/32). NB is for "normirani brus".
I'm interested to hear it in German, too.

Mailinmypocket - 24-5-2012 at 06:31

I am not sure if this answers your question, but the number after the "/" is the length of the ground glass part in millimeters.

As long as the first number is the same on both pieces you dont need to worry about the second one all that much unless the male piece will be too long and will prevent the joint from fitting all the way in.

Lambda-Eyde - 24-5-2012 at 07:22

Quote: Originally posted by Endimion17

What do you mean by eccentric joint system? Modern international and US system do fit together, but their lengths are not the same, therefore most, if not all holding clips are unusable.

How so? My keck clips still work...

IMO, what's weird is those Germans (and friends) who insist on using NS29 and NS14 ONLY - it's impractical and looks incredibly stupid. Last time I searched German eBay for glassware I found a 50 ml addition funnel with a NS29 joint and a 2000 ml addition funnel with a NS14 joint - ridiculous

I prefer a mix of NS24 and NS19 for most things with a few NS14 for inlets and thermometers and NS29 reserved for the biggest flasks.

Quote: Originally posted by Endimion17

BTW, how are different "kids" of joints called in German? I understand what normschliff means as we use the schliff word in Croatia. How do you call "female" and "male" joints?
We call it, loosely translated to English, a "slot" (ležište) and a "core" (jezgra). For example, a female NS14 joint, we say NB-L (14/23), and for a male NS29 we say NB-J (29/32). NB is for "normirani brus".
I'm interested to hear it in German, too.

They call it "hülse" and "kerne" iirc.

Endimion17 - 24-5-2012 at 08:35

Quote: Originally posted by Lambda-Eyde

How so? My keck clips still work...

They're too stretched. I don't like to stress them because they're expensive, and just the thought of spending almost 4€ on a piece of plastic that fails in acidic environment gives me the creeps. They do fail, splitting like a banana when you need them.

Quote:

I prefer a mix of NS24 and NS19 for most things with a few NS14 for inlets and thermometers and NS29 reserved for the biggest flasks.

The best thing is to try to use one standard, but to be openminded at the same time. A bit of flexibility is needed. Being all fanatic about one joint size is ridiculous, I agree.

Quote:

They call it "hülse" and "kerne" iirc.

It's obvious the male joint is pretty much everywhere called a core, but the name for the female one is closest to "sleeve".

What are the English names for the equivalents found in stopcocks? Shell and a plug?
We call the rotating part trn (thorn), and the female part šalica (cup). At least, that's the flameworker lingo.
What about bokmål?

[Edited on 24-5-2012 by Endimion17]