Sciencemadness Discussion Board

24/40, 24/29, 29/32, what is the best?

Blunotte - 28-3-2021 at 08:59

Goodmorning everyone :)
I am thinking of renovating my ancient laboratory, and I am undecided which glassware kit to buy.
In particular, my problem is choosing the best type of joint, but I don't know what practical differences exist between them.
For example, between 24/40 and 24/29, which one to choose?
And why are there so many types that are very similar in diameter to each other?
Thank you all :)

PS: The kit I would like to purchase would probably be this (the price seems good to me, less than 200$,some other advice is welcome):

Immagine.jpg - 99kB

[Edited on 28-3-2021 by Blunotte]

Antigua - 28-3-2021 at 09:07

Generally, 24/29 and 24/40 are considered "american". These are the most used standards in Chinese glass too. So if you aim to buy all/most of your glass from Chinese suppliers, then these are the way to go. 24/40's joint lenght is larger than 24/29's but they're compatibile with each other. I wouldn't say that either of them are superior really, the 29 milimeters of joint surface is more than enough to keep a seal. So whatever is more available and cheaper for you. 29/32 is more of an European standard (at least in Eastern Europe it's commonly used) and may be harder to get on Ali or eBay. So pretty much it comes down to availability! Keep in mind that 29 is a bit larger than 24.

Blunotte - 28-3-2021 at 09:17

Hi Antigua, thanks for the explanation: :)

In fact, all the glassware I currently have is 29/32 (I mostly have a lot of round bottom flasks), but I see it's hard to find, so I thought about a total refurb, rather than additions.

So if I bought the 24/40, it would then be compatible with a future 24/29, great to know, thanks, I think this will be the path I will choose :)

Antigua - 28-3-2021 at 09:26

I highly advise you to get some 24 to 29 and 29 to 24 adapters. They are very cheap and they solve any joint problems one might have. I once bought a set of adapters from 14 to 29 and never had to worry whether the flasks I have are the right joint sizes.

Texium - 28-3-2021 at 10:13

Historically, 24/40 has been more common in America while 24/29 is more common in Europe. Likewise, for 29 mm joints, 29/42 is seen more commonly in America while you'll see 29/32 in Europe. Nowadays though with glassware widely available online and rarely purchased locally, it isn't especially relevant which one you go with. I would recommend going with 24 mm though, whether you choose 24/40 or 24/29. 29 mm glassware is less commonly available in general, and there tends to be less variety of it available. For instance, you can easily find 29/xx flasks, but you might struggle to find a Dean-Stark trap. Also, 29/xx flasks tend to have a lower limit of about 250 mL, especially for multi-neck flasks, whereas 24/xx flasks can be found easily as small as 50 mL. Unless you want to work on multi-liter scale all the time, 24/xx will cover everything you need to do.

Another thing worth considering is 14 mm. Available in 14/20 (US) or 14/23 (international), which are also cross-compatible, it is a very versatile size for glassware as well. Single and multi-necked flasks are readily available up to 500 mL and most everything that you can find in 24/xx can be found in 14/xx as well. It's good to have a 14/xx kit because when working with smaller scales, using 24/xx glassware can lead to heavy mechanical losses. 14/xx glassware is generally less expensive too. I actually use 14/20 for most stuff, and only break out the 24/40 for stuff where a large volume is required, like steam distillation, or bulk preparation of nitric acid.

metalresearcher - 28-3-2021 at 12:31

I also have mostly 29/32 glassware, does that mean I cannot use 24/40 ?

Dr.Bob - 28-3-2021 at 17:11

It also depends on where you are. If in the US, 24/40 is the most common, although I have lots of 29/42 stuff for sale, if you are in the US. Outside of the US, there are other sizes that may be more common.

Sulaiman - 28-3-2021 at 17:56

Random ramblings...
. There is no glassware size that satisfies all needs
sometimes smaller is better, other times I want much larger.
. Glassware size tends to influence
- hazard per experiment/procedure
- cost; heating, stirring, cooling, filtering....
- required workspace area
- quantity of chemicals purchased (e.g. 100ml vs 500ml vs 5l)
- storage space for chemicals
- safety of chemical storage (small spill or fire vs large one)
- quantity of waste to deal with.

Due to cost I have bought mostly new Chinese glassware and used quickfit.
If you can afford it, glassware with good joints is very nice to use.
Chinese glassware is very capable but...

It seems that 24/40 still gives the most options on eBay etc.
(most of my stuff is 24/29)

PS Lately I have specifically chosen GG17 glass if from China - it looks and feels good
- time will tell..

[Edited on 29-3-2021 by Sulaiman]

Fyndium - 29-3-2021 at 01:15

One useful info first:

- 29/32 and 29/42 are usually always interchangeable. Only some very tight angles could cause issues fitting 42 male into 32 female, but I never had this issue with any combination.

- 24/29 and 24/40 are usually also always interchangeable. Same as above.

- Most everything can be fitted with adapters. I have 29* glassware from older ages, and new 24* glassware, and a bag of adapters m29>f24 and f29>m24 to fit all together. Issue with adapters is that equipment height can rise quickly and may not fit in your fume hood or workspace and it also causes more torque stress so a little more care must be taken when mounting clamps.

In eBay at least, 24* seem to have the widest and cheapest selection of glassware, so I would go with that. You can freely upgrade and downgrade from minor to major size and get all the equipment. I would suggest this size to all amateurs and general chemistry. Larger joint sizes come handy when upping glassware size to something like +5 liters.

If you need and intend to make only small experiments, smaller joint size like 14* could provide useful. Mechanical losses from large equipment go up quickly - try distilling few mL of liquid in 29/32 glassware, and you might end up nothing useful.

Those kits are good bang for buck usually. Just maybe hit an extra fritted funnel there, a stirmantle/plate and lab jack and 4-6 clamps and bossheads and you're good to go. If you're willing to invest half k$ at start, you'll get pretty much all equipment you need for a long time, instead of constantly ordering little parcels here and there, like I do. :D

Blunotte - 8-5-2021 at 05:11

Goodmorning everyone
Finally the glassware has arrived (perfect packaging), and this is my first setup: distillation of denaturated alcohol at 99°.
Everything works fine, now I'll try to start using it

immagine.jpg - 366kB

PS: I know, the heating mantle is not the best, and the Liebig had to be turned with the tubes upwards, and the receiving balloon had to be connected via the dripper, but I only took a picture at the beginning, when I quickly assembled everything

[Edited on 8-5-2021 by Blunotte]

Texium - 8-5-2021 at 05:21

Oooo bad bad bad... you’re heating a closed system! You need to include some way for pressure to escape, either by using an open vacuum take-off adapter between the condenser and the receiving flask, or by removing one of the stoppers that you have in the receiving flask (I’m guessing that one probably removed itself, or the apparatus popped open somewhere else during the distillation). Don’t worry, I made the exact same mistake on my first distillation.

Blunotte - 8-5-2021 at 05:25

Hi Texium, I don't know if you can see from the image, but one of the two caps of the receiving balloon was only partially inserted, just to avoid overpressure (I made this mistake years ago and I immediately regretted it :D)

Keras - 8-5-2021 at 05:33

Whoops [redacted]

I use CN19 Rodaviss glassware. Just to mention alternatives exist :)

[Edited on 8-5-2021 by Keras]

Texium - 8-5-2021 at 05:35

Quote: Originally posted by Blunotte  
Hi Texium, I don't know if you can see from the image, but one of the two caps of the receiving balloon was only partially inserted, just to avoid overpressure (I made this mistake years ago and I immediately regretted it :D)
Ah, no, I couldn’t see that in the picture you posted, but that’s good

Keras - 8-5-2021 at 05:47

This is anyway loosely stoppered. When you distill, you want to use Keck clips and grease to make sure your joints are sealed. Especially if you distill something that could solidify on the ground glass surfaces.

That’s the Rodaviss system main advantage: no clips, no need for grease, and it’s sealed with teflon-like rugged rubber joints. It’s more expensive, though.

Blunotte - 8-5-2021 at 09:50

Rodaviss system is very nice, but I never found them on Internet at rasonable prices... :(

Keras - 8-5-2021 at 11:00

Quote: Originally posted by Blunotte  
Rodaviss system is very nice, but I never found them on Internet at rasonable prices... :(

It’s not that expensive, but Chinese manufacturers don’t use it, I think the system is patented. My glassblower claims a single CN19 rugged Rodaviss joint costs him € 7.

It’s more frequent in Europe, I guess? Anyway, it’s a nice standard.

S.C. Wack - 8-5-2021 at 12:39

Quote: Originally posted by Blunotte  
one of the two caps of the receiving balloon was only partially inserted

A drying tube with CaCl2 or just cotton would be preferable.

pneumatician - 8-5-2021 at 14:34

Quote: Originally posted by Blunotte  

PS: I know, the heating mantle is not the best

oh, I want to buy one like this of 3L for occasional use, no problem heating the flask, all ok, heat around the flask?

In my experience: 24/40 (usa standar) for low volumes, no more than 2L, I've one of 10L as is near impossible to clean with brushes.

From here the more volume and solid the matter, the wider the mouth, but if is only for a repetitive use for some easy liquid to clean like alcohol...

14/23 for low volumes, 5-100ml, 29/32 is a european standar, 24/29 aussie and chinese standar?... so it depends of what and how many. In the end you have a pouporri of joints and adapters or a mega lot of glassware :-)

Sometimes the matter after distil. is so hard and indisoluble... or you search info before or use a reactor or if yuo want to recover what remain inside the flask your only option is offer it in sacrifice :-(

[Edited on 8-5-2021 by pneumatician]

Blunotte - 9-5-2021 at 04:43

Quote: Originally posted by pneumatician  
Quote: Originally posted by Blunotte  

PS: I know, the heating mantle is not the best

oh, I want to buy one like this of 3L for occasional use, no problem heating the flask, all ok, heat around the flask?...
It works perfectly, only the first few times it smells like hell and then you have to clean the RB with alcohol :(
For the rest, fine :)

pneumatician - 9-5-2021 at 05:59

oh yes, normally the manual say: put at max temp until fumes appeard, stop, when no fumes, start again until fumes and so on until no more fumes.