Sciencemadness Discussion Board - How should I choose glass joint size?

How should I choose glass joint size?

fusso - 14-4-2018 at 18:25

I'm about to enter the "pro" glassware world, ie doing chemistry with round bottom flasks, condensers etc instead of test tubes and beakers. But I don't know how to choose glassware joints for the apparatus

. Any tips?

happyfooddance - 14-4-2018 at 18:38

What amount of chemicals do you want to work with? Are you experimenting with chemical reactions or trying to produce large amounts of solvents. What are your interests?

In general, for experimenting, smaller is better.

Smaller is also cheaper.

ninhydric1 - 14-4-2018 at 18:42

If you are dealing with smaller quantities, quite a few people on this forum have ordered 14/20 distillation glassware. I, myself, own a 24/29 distillation setup, as well as a 24/29 separatory funnel, which is good for medium to large-scale reactions.

Tsjerk - 14-4-2018 at 20:39

Not knowing how much product you want to produce I would advise to buy a 14/20 distillation kit. This is already big enough to learn all possible techniques you can with a distillation kit.
When you produce something that is worth weighing in milligrams it is what you will ever need.

I'm a big fanboy of microscale chemistry. If you can go big you can go small. The smaller your scale, the less space you need, fit the setup. Temperature maintenance becomes easily doable when working on a milliliter scale, reactants become so easily spend you will run an extra optimization run for the heck of it.

What it all comes down to is that the glass parts should be as small as you can get them; small is cheap, quick, easy, often.

If you are willing to invest, please invest in apparatuses supporting the micro scale future of your lab by buying a milligram scale, a small magnetic steerer/heatermantle, a way to evaporate solvents (improvised rotovap).

The only good reason to start big is when you need a lot of kilos of your product. As long as you just want to test something anything bigger than ten grams is throwing away money.

Difficult choice

Sulaiman - 15-4-2018 at 01:04

I have a cute NS10 Quickfit kit and a cheaper Chinese NS24 kit that I use most of the time.
I doubt that there is an 'ideal' size kit, but I'm fairly confident that NS10 is too small for a beginner, and NS24 may be slightly too large.

For all but the simplest distillations quite a bit of kit is required;
. glassware
. stand(s) and clamps
. heating (ideally with stirring)
. cooling (running water or a water/ice recirculating pump system)

All of this kit has to fit on your work area and into your storage area.
My NS24 kit takes up maybe 10x the storage space of similar NS10 kit

I suggest that you look at prices from wherever you intend buying from,
(e.g. your local eBay) and compare overall costs for a COMPLETE kit,
including a suitable heating mantle, stands, cooling etc.
and
the larger the scale of your glassware, the larger your volume of solvents and product storage containers

Last, but most contentious, is glassware quality.
Opinions differ: I love Quickfit, but I buy cheap Chinese

[Edited on 15-4-2018 by Sulaiman]

Bert - 15-4-2018 at 01:25

I chose to go with 24/40, but my parameters are likely different from yours.

I was trained to believe the personal dangers of my area of chemical activities were more related to number of repetitions than the quantities involved, beyond the fairly small ammounts required to seriously injure or kill me (I was specifically told at one point that beyond X ammount, limiting batch size was purely a courtesy to the neighbors).

That is to say, if you're going to synthesize something to USE, make enough so you can run for some time before requiring another synthesis.

If you are experimenting and learning, go for the smaller sizes- It's probably safer, certainly more economical and easier on storage space.

LearnedAmateur - 15-4-2018 at 03:14

Most of my glassware is 14/23, my RBFs (100 and 250mL) and 50mL separatory funnel are 19/26 and I use an adapter to connect with my other glassware. I also have a 60mL 24/29 fritted filter, again with an adapter in order to use it; AFAIK, you can’t really get smaller joint sizes for these so that’s why I went with that size, since there needs to be room for the tube and plenty of air space to pull a vacuum.

My experimentations are on the millilitre scale, the max I usually have to deal with is about 200mL - for larger runs I’ll split it into smaller batches but this is rare and only really involves generating salts which I’ll do in jars and other household containers. Helps with space too since I only have a desk to perform all of my procedures.

aga - 15-4-2018 at 03:46

All of mine is 24/29.

Unless you have endless space and money, choose 24/29 or 14/23 and stick with it.

Amazing how many bits of glass build up over a short time.

JJay - 15-4-2018 at 04:43

It's hard to go wrong with N24. I slightly prefer 24/40 for adapters and 24/29 for flasks. Generally, an apparatus constructed entirely with 24/40 joints is more stable and requires less joint grease, but 24/29 joints are easier to get apart when stuck. 24/xx is generally compatible with other 24/xx, although you may encounter some occasional off pieces on things like non-addition sep funnels. 24/29 is generally the cheapest, and the flask sizes can be anywhere from 25 mL to 10 L and probably larger or smaller (so you can do reactions on a 2.5 mL scale or a 5 L scale).

My largest flask is 3 L, and I have considered obtaining something larger, but that's big enough for most tasks that I want to do as a hobbyist. 2 L is probably big enough for almost everything, really... once in a while I want to do something in extremely dilute conditions and wish I had bucket-size flasks and tanker trucks of solvent, but usually it is pretty easy to scale things down as long as the quantities aren't so tiny that you can't avoid massive mechanical losses. There are things that I use 20 L buckets for, and if I had massive flasks, I would probably use them, but I'm not even sure where I would store something like that....

I use 14/10 microscale glassware with screw fittings for the really small stuff. It is largely compatible with 14/20, and I use 14/20 replacement parts when possible since they are much cheaper than 14/10.

I have noticed that most of the top-notch YouTube chemists (in particular, Nile Red, Nurdrage, and Chem Player) use a range of joint sizes with adapters. I think Doug's Lab belongs in that echelon also, and he seems to use mainly N24 (pretty sure UC235 did too).

fusso - 15-4-2018 at 09:07

Quote: Originally posted by JJay

It's hard to go wrong with N24. I slightly prefer 24/40 for adapters and 24/29 for flasks. Generally, an apparatus constructed entirely with 24/40 joints is more stable and requires less joint grease, but 24/29 joints are easier to get apart when stuck. 24/xx is generally compatible with other 24/xx, although you may encounter some occasional off pieces on things like non-addition sep funnels. 24/29 is generally the cheapest, and the flask sizes can be anywhere from 25 mL to 10 L and probably larger or smaller (so you can do reactions on a 2.5 mL scale or a 5 L scale).

My largest flask is 3 L, and I have considered obtaining something larger, but that's big enough for most tasks that I want to do as a hobbyist. 2 L is probably big enough for almost everything, really... once in a while I want to do something in extremely dilute conditions and wish I had bucket-size flasks and tanker trucks of solvent, but usually it is pretty easy to scale things down as long as the quantities aren't so tiny that you can't avoid massive mechanical losses. There are things that I use 20 L buckets for, and if I had massive flasks, I would probably use them, but I'm not even sure where I would store something like that....

I use 14/10 microscale glassware with screw fittings for the really small stuff. It is largely compatible with 14/20, and I use 14/20 replacement parts when possible since they are much cheaper than 14/10.

I have noticed that most of the top-notch YouTube chemists (in particular, Nile Red, Nurdrage, and Chem Player) use a range of joint sizes with adapters. I think Doug's Lab belongs in that echelon also, and he seems to use mainly N24 (pretty sure UC235 did too).

@JJay whats N24?

fusso - 15-4-2018 at 09:08

Thx for the info. I'd like to go with ~5-10g scale for synthesis and ~150ml solvent distillation but I actually want to know what the numbers like 14/20 & 24/29 mean? And compatibility issues like JJay said "24/xx is generally compatible with other 24/xx". Thats my main trouble when I'm considering sizes.

JJay - 15-4-2018 at 09:24

The first number is the width in millimeters at the widest point. The second number is the length of the joint in millimeters. Standard taper is 1:10 for ground glass stoppers (also most lab corks and rubber stoppers). N24 is a notation I've seen used to describe 24/40 and 24/29 joints.

fusso - 15-4-2018 at 11:25

Quote: Originally posted by JJay

The first number is the width in millimeters at the widest point. The second number is the length of the joint in millimeters. Standard taper is 1:10 for ground glass stoppers (also most lab corks and rubber stoppers). N24 is a notation I've seen used to describe 24/40 and 24/29 joints.

and what's 1:10?

JJay - 15-4-2018 at 11:32

10%

fusso - 15-4-2018 at 11:37

Quote: Originally posted by JJay

10%

Slope of the joint // to the ___(?) axis right?

fusso - 15-4-2018 at 11:46

For the sep funnel, should I use conical or cylindrical?
Should I use one with narrower tip at the stopcock end or one with ground joint end like this img? https://www.aliexpress.com/item/1000ml-24-40-Glass-Separator...
Should I use PTFE or glass stopcock?

Plunkett - 15-4-2018 at 12:17

It is difficult to see in the picture, but if the separatory funnel you linked is like the one I bought from China (seller sam10086, a Deschem distributor I believe), there is a narrower tip inside of the ground joint, like the ones without the jointed end. I would go for the funnel with the ground glass joint end because you can also use it as an addition funnel. The joint does get in the way sometimes but I think overall it is more versatile.

[Edited on 15-4-2018 by Plunkett]

LearnedAmateur - 15-4-2018 at 12:20

Strictly, the bulbous design is a separatory and the straight tube is an addition funnel but they’re very often used interchangeably - I myself have the straight tube since what matters is the stopcock and the narrow point at the end where layer separation can be more tightly controlled. Mine also has a ground joint after the stopcock, but it shouldn’t matter if you don’t mind holding it for a separation, but if you need to do a long addition for instance (dropwise or a trickle) then get a jointed tube so you’re not holding it for hours or minutes. Also don’t forget to pressure equalise on either side if using a jointed funnel otherwise air will bubble through or the flow will completely stop!

Both PFTE and glass are just as good as one another IME, but I prefer the former because it is less likely to become frozen, such as if you have a thin layer of some liquid trapped and it solidifies or you are dealing with hot solutions in some circumstances. Both should be highly resilient to chemical attack though, so it’s up to your discretion - how tightly the screw is done up will mostly determine what I mentioned in the last sentence.

This is the design I go with for all of my addition and separation needs, I stand by it. Perfect size for everything I’ve needed it for too.

[Edited on 15-4-2018 by LearnedAmateur]

8332A3DC-298E-4A82-8A2E-C9582EE4B706.jpeg - 1.7MB

JJay - 15-4-2018 at 12:22

It means for every centimeter, the joint tapers by a millimeter.

I don't think the shape of a sep funnel matters much, but I prefer conical for actual sep funnels and cylindrical for addition funnels... the cylindrical shape makes it easier to estimate the volume remaining in the funnel. I can't think of many situations where a PTFE stopcock isn't better than a glass one... perhaps when handling hot liquids that could cause the PTFE stopcock to jam and bind or handling really hot liquids that could destroy the stopcock... but how often do you handle hot liquids in a sep funnel.... Glass is fine for most purposes but needs to be greased, so your product will probably be contaminated with fluorinated silicone grease, and glass can be attacked by strong alkali... at ordinary temperatures, PTFE is pretty inert to almost every substance you're likely to encounter unless you're doing something exotic like home fluoropolymer chemistry (for example, apparently, perfluorinated decalin can dissolve PTFE at 350 C). Glass is somewhat easier to clean than PTFE in my opinion, but that's rarely even a minor issue with stopcocks.

You might save a few bucks by getting a sep funnel without a ground glass joint below the stopcock, but when I bought my second 1L sep funnel (a sep funnel is a pretty important piece of equipment, and no one wants to wait a month for a new one), I bought one with a ground glass joint below the stopcock. Actually, I bought that same sep funnel, and it is high quality and came with a standard stopper with a cool bulbous flare handle. It can work just fine as an ordinary sep funnel. Just don't attach the joint directly to an apparatus to drain the contents unless you have some way to relieve pressure (draining it into a beaker is fine, but draining it directly into an RBF is probably not a good move).

I personally almost never use non-equalizing addition funnels, but that sep funnel can double as a non-equalizing addition funnel in a pinch. I hardly ever use mine because I have a well-used GG-17 funnel with a nonstandard stopper that works fine for separations, and I intend to continue using it until it breaks, with the Deschem funnel as a backup. I also have a cylindrical pressure-equalizing addition funnel that I use for most controlled additions.

S.C. Wack - 15-4-2018 at 14:13

24/40 is big for your scale. 19/22 is a great size; easier in many ways to work with than larger pieces.

fusso - 15-4-2018 at 17:53

Will a piece of glassware of specific size eg 500ml round bot flask have specific joint size eg 24/29? Or are there a few joint sizes to choose from eg 19/22 & 24/29?

DavidJR - 15-4-2018 at 18:54

Within reason you can buy lots of combinations of flask size/joint size. However larger volume flasks will be more readily found with the larger joints. E.g. good luck finding a 2L flask with a 14/23 joint...

I went for 24/29 in large part because you can get a wide range of glassware easily and cheaply as it's a very popular size. However I think the most important thing is to pick one size and stick to it, that way you have the most flexibility.

Dr.Bob - 15-4-2018 at 19:13

US sizes are typically 14/20, 19/22, 24/40, and 29/42, which are ideal for scales of 10-250 ml, 50-500 ml, 100-1000 ml, and 250-25L scales. So for most home chemists, I recommend 14/20 as a starter, and then 24/40 or larger if you need to go bigger, for solvent distillations, and bigger reactions. 24/40 is the easiest size to find parts for, followed by 14/20, which is less common, but usually cheaper as smaller scale. 19/22 is hard to find cheap parts for in the US.

Non-US countries have other various joint lengths, like 14/23, 14/29, etc, but the taper is the same, so often they interchange OK.

XeonTheMGPony - 16-4-2018 at 04:38

All so first select a size range, then research what is the most common in that range then select that.

I do large volume runs when I do any thing, as Bert n I share commonality, and the rules of numbers come in to play, the more you do some thing the more the odds of some thing bad happening, so it is better to do one big run very care fully then doing allot of small runs!

So I went with 24/40 since it meets my scale requirements and it is the most common out there. That was my selection method.

Dr.Bob - 16-4-2018 at 09:23

That makes sense. If you are looking for 24/40 parts, there are many people selling them on Amazon, Ebay, and other spots. I also have lots of 24/40 accessories, like addition funnels (with and w/o equalization arms), Dean- Stark Traps, various adapters, condensers, and much more.

PhenethylamineMachine - 16-4-2018 at 09:32

To the original poster: have you not worked with any of this laboratory equipment previously?

fusso - 28-4-2018 at 10:32

@Pheneth...
I havent worked with them before, I just worked with basic beakers, test tubes, conical falsks etc, but definitely havent with those with glass joints

Texium - 28-4-2018 at 10:41

I use both 14/20 and 24/40. I started out with 24/40 because that's what I was able to get my hands on out of luck, originally, but looking back, it would have been easier to start out with 14/20. I use both types about equally now, but it's advisable to start small.

19/22 is an awkward joint size, in my opinion, and I wouldn't recommend it. While it can be seen as a happy medium for amateur scale work, it seems to be mainly used in teaching labs. Thus it's hard to find more specialized glassware in that size that you wouldn't normally find in an organic teaching lab kit. The research lab that I work in uses only 14/20 and 24/40 pieces like I do at home. Adapters that convert from 14/20 to 24/40 are common too if you ever need to bridge the gap for any reason.

Leafs - 28-4-2018 at 17:56

I went with 24/29.

Sidenote question though for anyone.

I know that 24/29 male joint will fit inside a 24/40 female joint, but will 24/40 male (like a condenser) fit inside a 24/29 female (flask)? Don't think it would be ideal though from an efficiency standpoint having some of the joint hanging inside like that.

Melgar - 28-4-2018 at 21:38

Yeah, both "24" sizes fit together both ways. It's just that they only touch each other for 29 mm of their length.

Personally, I started with 24/40 because it's easier to find. But then I realized that my mistakes tended to do a lot less damage when I'd experiment at smaller scales, and eventually put together a 14/20 set. It's also allowed me to experiment without using up as much in the way of reagents.

The only annoying part here is that often I need to distill a fairly large amount of liquid, which isn't practical using 14/20 gear; the largest flasks they make are maybe 250 mL and even those are rare. It also seems like it's practically impossible to find flat-bottom flasks in 14/20, and I don't always want or need some sort of bath for heating my flask, or feel like messing around with setting up a stand and clamps. So for that, I just use a 24/40 flat-bottom flask, and then have a 14/20 adapter that I use with it. It means that distillations take a bit longer, but I can always get a 24/40 condenser if that becomes a problem.

A really nice benefit of 14/20 glassware is that due to the cube-square law regarding material strength, it's much less common to accidentally break 14/20 glassware by dropping it from about the height of a table. Virtually impossible NOT to break 24/40 glass.

Oh yeah, I also think those 14/20 all-in-one distillation head contraptions look really cool, and own perhaps three. None of the really complicated ones, but still, being able to have a one-piece distillation head is pretty convenient.

Magpie - 29-4-2018 at 10:02

I like 19/22 because that is the scale (50-100g) that I normally work in. If I need to go largerto make reagents I use adapters to 24/40.

I have a hood that is 4' wide. The 19/22 setups fit much better than the 24/40, both for width and height.

LearnedAmateur - 2-5-2018 at 03:41

Quote: Originally posted by Melgar

A really nice benefit of 14/20 glassware is that due to the cube-square law regarding material strength, it's much less common to accidentally break 14/20 glassware by dropping it from about the height of a table. Virtually impossible NOT to break 24/40 glass.

And 19/26 it seems, my poor 250mL RBF just suffered an incurable star fracture from a 5cm drop onto the base of my retort stand. I was just getting back into experimenting as well just to take the piss, the hydrolysis of APAP then a Sandmeyer reaction to hydroquinone - luckily I saw it before I hit the thing with a flame! ‘Tis a sad day, but oh well, time to go shopping and this time I’ll try find a 14/23.

945044F6-56DA-44AA-86CF-12C6E6EDA7D3.jpeg - 153kB

Soxhlet extractor: upper female joint size?

fusso - 6-5-2018 at 14:02

So I think I also need a soxhlet extractor for extractions. However I'm not sure what size should the upper female joint be. Can someone give me some advices?

DavidJR - 6-5-2018 at 14:25

Quote: Originally posted by LearnedAmateur

If you have a blowtorch then it's pretty easy to repair that sort of fracture. Just make sure to warm it up slowly, and even more importantly, to cool it down very slowly afterwards (i.e. flame-anneal the glass).

S.C. Wack - 6-5-2018 at 18:56

Quote: Originally posted by Dr.Bob

19/22 is hard to find cheap parts for in the US.

Until it eventually arrives from Laboy or aliexpress. Cheap 10/30 thermometers are harder. There's one on ebay for $11, only $26 shipping.

Quote: Originally posted by fusso

So I think I also need a soxhlet extractor for extractions. However I'm not sure what size should the upper female joint be. Can someone give me some advices?

It depends on scale. I love glass extraction thimbles for them and never have found a cheap source of cellulose thimbles. They're often found cheap because no one knows what they are, but IME they tend to be just a hair too big if American or small if Chinese for Pyrex Soxhlets.

[Edited on 7-5-2018 by S.C. Wack]

LearnedAmateur - 7-5-2018 at 01:01

Quote: Originally posted by DavidJR

Yeah, but nah, the number of times I thought I could get away with that just to end up with a pile of glass shards because one of the cracks shoots around the piece making the problem even worse. I do try to heat outside the crack then slowly move in to limit propagation but it’ll fuse then slowly creep back and wham, I’ve got two bits when there should only be one. I’ll just stick to using it as a low temperature vessel rather than risk it going in the bin, maybe I’ll give it a go if I have access to a MAPP torch in the future but my little torch won’t be able to fix that.

DavidJR - 7-5-2018 at 04:04

Quote: Originally posted by LearnedAmateur

I've had success just using my el-cheapo eBay butane torch (only issue with that torch is that it occasionally emits flames from orifices which are not supposed to emit flames). Then again plenty of times i've tried to repair glassware and it's gone very wrong, but given that it was broken anyway, I don't consider it much of a loss if I break it even more.

sodium_stearate - 7-5-2018 at 04:49

I'd like to see some pictures of some of the repaired
glassware! That sounds very interesting about being
able to make repairs using a torch.

DavidJR - 7-5-2018 at 05:17

Quote: Originally posted by sodium_stearate

I'd like to see some pictures of some of the repaired
glassware! That sounds very interesting about being
able to make repairs using a torch.

I had a RBF star fracture very similar to the pic posted by LearnedAmateur. It was either a 250ml or 500ml flask, don't remember. I've looked closely at all of my flasks and honestly I can't figure out which one it was. Maybe if I looked at them with a polariscope...

I've never had good results trying to repair glassware which has actually separated into multiple pieces. However, if it's cracked but still in one piece, then it's not too difficult.

You need to heat it up slowly and evenly or the crack will propagate further. Start with a small flame and keep it moving over a large area surrounding the crack.

As the area surrounding the crack heats up, you can turn up the torch and focus on a smaller area, while still keeping the flame moving. It'll eventually glow a dull red/orange and you can then blast the crack with lots of heat without moving the flame much. You will suddenly see the crack join back together and become more transparent (like the difference between a greased and ungreased joint). Continue heating strongly for a few minutes to ensure a good repair.

Then very slowly cool the piece, using a gradually reducing size of flame/increasing distance, again constantly moving flame. If you cool it too quickly, the glass will be weak due to stresses trapped in it.

Disclaimer: I'm no glassblower so take this advice with a grain of salt.

Dr.Bob - 7-5-2018 at 10:37

Quote: Originally posted by fusso

So I think I also need a soxhlet extractor for extractions. However I'm not sure what size should the upper female joint be. Can someone give me some advices?

It is about volume of liquid you want to extract with. There are small, medium, large, and huge. The small only holds 30-40 ml in the top extractor, medium is maybe 50-60 ml, and large is over 100 ml. The amount of solvent needed in total is about triple that. I would tend to stick with medium as a starting point unless you know what scale you are considering.

fusso - 7-5-2018 at 11:25

Quote: Originally posted by Dr.Bob

Quote: Originally posted by fusso

So I think I also need a soxhlet extractor for extractions. However I'm not sure what size should the upper female joint be. Can someone give me some advices?

What's the corresponding female joint size above the thimble?

Texium - 7-5-2018 at 11:46

The smallest Soxhlet I've seen has a 34/45 joint. 45/50, 50/50, and 55/50 are typical for medium-large ones. Bigger than that and you get some other wonky large joint sizes going as big as 80 or 90 mm.

S.C. Wack - 7-5-2018 at 14:40

Download and read the catalog from Ace Glass. It's a great reference. Like that Soxhlet on ebay I turned down with the 55/50 base because where am I ever going to find a used condenser for it. Turns out all I needed was a little reducing adapter.

[Edited on 7-5-2018 by S.C. Wack]

Dr.Bob - 7-5-2018 at 16:24

small, cond is 34/45
med, cond is 45/50
large, cond is 55/50

S.C. Wack - 15-7-2018 at 20:23

Quote: Originally posted by S.C. Wack

Quote: Originally posted by Dr.Bob

19/22 is hard to find cheap parts for in the US.

Until it eventually arrives from Laboy or aliexpress. Cheap 10/30 thermometers are harder. There's one on ebay for $11, only $26 shipping.

A BTW update after trying aliexpress I see why that store has filled like 5 orders even though they're so cheap. They took my information but refused me in the end and locked my account.

No problems with Laboy except it costs more and there's some things I wanted, especially gas dispersion that Laboy doesn't offer. They sell 10/18 thermometers but these seem to fit 10/30 better and appear to be closer to 10/21. So I'd recommend them for "10/30" thermometers except they're pricey for the quality, have the usual faint scale, and one has to take their word for it on the immersion, because there is no line and no writing.

[Edited on 16-7-2018 by S.C. Wack]

zed - 16-7-2018 at 15:31

Umm. Deschem and Nanshin, have online E-bay stores, that you can peruse as required.

Lots of Soxhlets, adapters, and friendly prices.

Larger neck provides easier access, and the capacity to accept larger diameter items.

https://www.ebay.com/sch/m.html?_ssn=deschem&_from=R40&a...

[Edited on 16-7-2018 by zed]

S.C. Wack - 17-7-2018 at 14:40

A larger neck Soxhlet, the one I was referring to with the 55/50 base and should have bid high on, are the Ace 6810's. 500-5000 ml. Brilliant finding 24/40 on ebay...unfortunately neither of them sell 19/22 except for an adapter to 24/40. Laboy sells some weird things including 19/22; in theory the anything store on aliexpress had a lot more, at prices too good to be true.