I recently got a new set of glassware and I noticed a few things both when it arrived and after some use.
First of all, the seller claimed that the joints were all 24/40 which I was happy with cause in the U.S. its an easy size to get additional parts for,
but when the glassware arrived it was all labeled 24/28. Does anyone know if this is just a mislabeling? Cause I couldn't find anything on 24/28 ST,
its like the size doesn't exist when I went searching for adapters.
Secondly, the thermometer section on the end of the distillation head seems to be leaking. I thought I could solve the problem with some duct tape to
help seal it but gases are still leaking through. (its hard to tell in the picture but there is some white gas coming off) Does anyone know how to
re-seal or make an airtight seal there? Cause I'm planning on producing elemental bromine and I really don't want that leaking out into the lab space
despite my ventilation set-up, I just don't trust that red gas.
Looking at the photos the ground glass joints don't look ground. The normal frosting is not there. The thermometer adapter, use Teflon plumbers tape
to wrap around the thermometer to seal. You will lose being able to see a small section of numbers but hopefully the ones you need will be visible. JnPS - 4-8-2016 at 17:47
It is ground glass, they're just greased and in use so the frost clears up, right? Or should they stay frosted after greasing too?RocksInHead - 4-8-2016 at 21:32
It is ground glass, they're just greased and in use so the frost clears up, right? Or should they stay frosted after greasing too?
Yea, they kinda clear up after greasing, so no worries there!
As for 24/28, it's probably just a misprint, if they do exist, they are super rare. You can even measure for yourself if it is a 24/40,
"The first number represents the outer diameter (OD) in millimeters (mm) at the widest point of the inner (male) joint. The second number represents
the ground glass length of the joint in millimeters. The most common US joints are 14/20 and 24/40." - Wikipedia
And as for the thermometer threads, do what highpower48 said and wrap PTFE sealant tape around the threads where you screw the cap on, you can get
them for as little as $0.99 a roll. Mine started leaking NO2 during a Nitric Acid synthesis!
[Edited on 5-8-2016 by RocksInHead]j_sum1 - 4-8-2016 at 21:53
This is the second time recently I have heard of 24/28 joints. Apparently there is at least one company labelling their joints as such. Functionally
equivalent to a 24/29 and so I would not worry.
I can think of a few scenarios where someone might measure differently and therefore label differently. They may or may not be different from a
standard joint. 1mm is not that much.
But do measure them to satisfy your curiosity.
What is of greater concern is that you ordered 24/40 and received something different. I would let your supplier know. This happened to me recently.
I was sent a free replacement. (Unfortunately it was intercepted by customs as
a potential drug-making device and I never received it. I did receive a visit
from the police though. But that's a whole 'nuther story.)NedsHead - 5-8-2016 at 00:40
if it's from China they probably wore out, broke or lost the #9 stamp so they just grabbed the brand new and never used #8 from the set, who's going
to notice right? Sulaiman - 5-8-2016 at 02:44
has your thermometer adapter got the little silicone compression sealing ring inside the top of the cap?JnPS - 5-8-2016 at 04:11
I'm not sure, I haven't taken a closer look at it, I've been shopping around for that PTFE sealant tape people have mentioned while I'm not busy being
rushed around doing stuff for a wedding in the family hissingnoise - 5-8-2016 at 06:20
Along with the rubber o-ring, there should properly be two teflon rings to protect the vulnerable rubber top and bottom, but t-tape wrapped tightly
around the thermometer until it forms a thick enough 'rope' that can just be slid up and down with effort will form a perfect seal if it's carefully
done.
(Unfortunately it was intercepted by customs as
a potential drug-making device and I never received it. 
I did receive a visit
from the police though. But that's a whole 'nuther story.)