Sciencemadness Discussion Board

24/40 thermometer pocket warning

Sulaiman - 17-3-2017 at 21:40

I just received a 100mm stem 24/40 thermometer pocket http://www.ebay.co.uk/itm/162276398639?_trksid=p2060353.m274...
should be perfect for my 500 ml flasks, but
the actual diameter of the joint is 23.5 mm
so the adaptor fits into a NS24 socket about 5mm too far,
the end of the stem touches the flask wall before a seal is achieved for the joint
and Keck clips don't keep the joint compressed.

I shall contact the seller today but I want to warn you all asap.

wg48 - 18-3-2017 at 12:30

Quote: Originally posted by Sulaiman  
I just received a 100mm stem 24/40 thermometer pocket http://www.ebay.co.uk/itm/162276398639?_trksid=p2060353.m274...
should be perfect for my 500 ml flasks, but
the actual diameter of the joint is 23.5 mm
so the adaptor fits into a NS24 socket about 5mm too far,
the end of the stem touches the flask wall before a seal is achieved for the joint
and Keck clips don't keep the joint compressed.

I shall contact the seller today but I want to warn you all asap.


Thats a good price. Does the joint fit snugly to some other known good female joints say quickfit?

I need one to modify to make a stirrer adapter so I don't care if its too long.

JJay - 18-3-2017 at 12:37

I have one of the same kind of flasks as yours, and my 100mm stem tube fits great. It is the standard supercheap variety from Hong Kong with a narrow opening, advertised as 182mm (182mm overall length actually), but it is free of defects.

I've been thinking about cutting an inch or so from my 200mm, but I think I might actually take it to a glassblower to do that since I will probably want to use it under vacuum.

Sulaiman - 18-3-2017 at 23:17

The joint is the correct taper and it fits other NS24 joints snugly,
but the top of the taper is c23.5 mm diameter, instead of 24 mm,
so the cone is 4 or 5 mm recessed into other sockets,
so Keck clips do not compress the joint.
The adapter length is OK for one-neck 500 ml rbf or the centre neck of a 3-neck 500 ml rbf,
if the joint was 24 mm it would fit nicely in a side-neck of a 3-neck 500 ml rbf, which is what I wanted it for.
I think that ptfe tape, or ideally sleeves, it will fit properly.

EDIT: Just received a 50% refund, so £1.34 total cost,

[Edited on 20-3-2017 by Sulaiman]