danton
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24/29 or 24/40
instead of a mixture of glassware i'd like to try and standardise the size with new purchases. What's a better choice 24/29 or 24/40? Any opinions?
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Tsjerk
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24/29 and 24/40 are compatible with another in almost all cases, the only difference is the length of the joint. Only when you have a piece of glass
with a 24/29 male joint and e.g. a very sharp bend or bulge it might not fit in a 24/40 female joint.
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Sir_Gawain
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I prefer 24/40 because if you have it in a clamp, there's still room at the top for a keck clip.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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Texium
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I personally prefer 24/40 because it feels a bit sturdier to me, and it’s what I’m used to here in the US. If you’re in the US (or Canada? I
think they also mainly use 24/40 but I’m not certain), you should probably go 24/40 because it is more common here. Used glassware sold in the US is
almost always 24/40, 14/20. If you’re in Europe or elsewhere, 24/29 is more common.
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danton
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Thanks for all the replies. Good points made. I was leaning towards 24/40 and the replies have convinced its the right way to go. Thanks everyone
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Lionel Spanner
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It really depends where you live. Outside North America, Australia and NZ, glassware with ISO standard joints (e.g. 24/29) is more readily available
than ASTM standard glassware (e.g. 24/40).
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j_sum1
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Most of my glassware is cheap Chinese 24/40.
I like the larger joint size because the joint is more stable. There is also more contact area between the parts which I think creates a better seal.
However, it is worth noting that because the taper is the same for both, and the 24/40 is longer, the inside diameter at the smallest point will be
less. I can't really think of applications where this is critical. Maybe if you are working at the limit of what your glassware can handle and you
don't have larger joint sizes available, a 24/29 will be more forgiving.
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Sulaiman
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As noted by others above,
24/29 and 24/40 are mostly interoperable
but mixing does leave some of the ground glass joint exposed to potential deposits.
To me, more important than the joint length is the joint quality :
. My glassware is mostly 24/29
- lots of new Chinese and quite a lot of used Pyrex/quickfit
29 mm is more than enough length for a good seal and for physical stability
My quickfit joints need only a small smear of grease to form a good seal
My Chinese glassware joints look good but actually need a lot of grease to seal them,
so much that when hot, grease dribbles from the joint and contaminates my experiments,
so I use ptfe tape instead of grease.
So
24/29 vs 24/40 is not really important to me.
I prefer to buy used quickfit over new cheap Chinese,
but if it was not for the availability of Cheap Chinese glassware I would have much less equipment,
CAUTION : Hobby Chemist, not Professional or even Amateur
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Mateo_swe
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In the past it was like this.
If you are located on Europe use 24/29, if in US use 24/40.
It might be easier to buy replacements and new glassware locally.
But nowadays all glassware are avaliable on the net from china so buying both varietys are no problems.
They can usually be mixed, ie. a 24/29 condenser fits in a 24/40 boiling flask and the other way around.
I use 24/29 and it works good.
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Texium
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I think you should still stick with the joint size that is most common in your country. Sure you can buy new glassware in whatever size you want, no
matter where you are in the world, but if you find a lot of used glassware locally, it’s probably going to have the joint size that is common in
your country. If the goal is to keep your collection consistent, and avoid mixing if possible, it would be sensible to stick to what’s common in
your region.
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Tsjerk
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I always had 24/29, but I noticed there were more 24/40 pieces available on AliExpress, so now I have both.
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Deathunter88
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24/40 just looks bad IMO (the ratio looks unbalanced), so I prefer 24/29 even if it means I have to pay extra to get it shipped from overseas.
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arkoma
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I have a pretty even mix of the two actually, and even though in the US, if i HAD to pick one it would be 24/29.
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ManyInterests
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I've never used anything other than 24/29. Some of my joints at 24/40, but that never caused a problem.
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Texium
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I think
this is an understated benefit of 24/40 that I’ve always taken for granted.
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