Niklas
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11 cm glass flange
So, on Sunday I got a 10 l round bottom flask of Kleinanzeigen for 50€ (just couldn’t say no to that), which has a glass flange rather than normal
ground joints to be used with a reactor lid. Normally this wouldn’t be much of a problem, it’s actually quite a bit nicer for such large glassware
in my opinion, but because this piece is from the GDR from before DIN was a thing it doesn’t follow the standardized sizes (DIN60 = 100 mm, DIN100 =
138 mm) and instead has an outside diameter of 11 cm.
Any idea where I could get a fitting lid or would anyone from Europe perhaps even have one around they would be willing to sell?
 
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Keras
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Lol. Viel Glück damit :p
Time to search for your local glassblower 
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MrDoctor
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they make PTFE reactor lids too, that would be far easier to commission than glass from a non-specialist, though it depends how it attaches, if it
needs to form a grease-vacuum on that flat surface like vacuum dessicators have. but if it just attaches like flanges normally interface with a
triclamp, then it would be very easy to commission a PTFE lid and just find the bulkhead screw-connector dimensions to tap the hole(s) with, or, have
them make you a O-ring compression fitting that you can shove a straight adaptor into, but having holes tapped so you can use existing reactor
fittings probably seems like the way to go.
You could always ask for a custom one from the places making these. odds are they make it themselves and they can probably just lathe down whatever
size they have bigger than your flask, to fit it, PTFE is after all, super easy to machine. Or just one made to spec, the designs are probably
parametric so they just enter the dimensions of the contact surface and the program automates the rest.
[Edited on 27-5-2025 by MrDoctor]
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davidfetter
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Keras, you beat me to it.
This is almost sure to require a custom build, and given the size, your best chance of success is with someone very much used to building custom
scientific glass. Once you're in that realm, you might consider someone who can remove the current fitting and replace it, or at least has
experience-based ideas as to what to do about your windfall.
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Niklas
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Hm yeah, I guess I‘ll go ask my university glassblower.. Didn’t think of the option of a PTFE-lid, may take that in consideration as well, but
I‘m worried about some stuff being able to diffuse through teflon so I‘ll keep that as a last resort.
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MrDoctor
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theres graphite-loaded PTFE stock blocks, it has a similar effect that mylar does in pretty much eliminating gas and moisture diffusion with a super
thin sheet of foil. also keep in mind most peoples opinions and experience on ptfe are based on its use as a liner or thread tape, which is also soft
enough that it can form a compression seal easily. im not so sure anything will cause you trouble through a thick block of hard teflon.
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Eleutheria
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It’s possible you can get away with a slightly oversized reactor lid, which isn’t ideal obviously. Right now there’s a great deal on eBay for a
brand new 4.5in (11.43cm) Wilmad O-ring reactor lid that’s super cheap in the US. It’s $26.99 right now... I doubt it’ll be available after a
few more days. I almost bought it just cause it’s so cheap for a brand new NOS reactor lid.
https://www.ebay.com/itm/224873834193?_skw=flange&itmmet...
The reactor lid would create a 0.215cm overhang around the lower flat flange you have on your flask. Double check my math though. It’s possible that
Chemglass or Ace reactor clamps could accommodate for this small amount of overhang.
This Frankenstein setup though between your 11cm OD flat flange and an 11.43cm OD O-ring flange may be feasible and I don’t see any cheaper option
then this really. I’d obviously be very cautious doing anything like this though if you consider mismatching parts to make it work. Depending on
what you’re trying to do, this setup could be safe (assuming the clamp you buy safely secures the flanges with the overhang). Probably best to not
consider doing anything near high pressure in this instance.
I’d wait to see what others keep saying though. I’m way too particular to use mismatched parts on reactors. The reactor lid I’ve pasted the link
to is also fairly limited on what you can even do with it. You may be able to get that lid modified to add ground joints and have the OD adjusted.
I’m just speculating as someone who has no knowledge on what a glassblower could do with the OD on a pre-manufactured reactor lid.
If it were me, I’d shelf that flask and scour listings online periodically until I find a surefire and safe replacement lid that perfectly fits that
flask. Since you’re in Europe, I wouldn’t have a clue on what a glassblower would charge you to make a perfectly fitted reactor lid, plus all the
ground joint attachment charges on top of that.
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Niklas
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Ended up getting things made by my university glassblower, he was so kind to do it for free 
 
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davidfetter
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Don't forget to guide people into this profession. We're gonna need a lot of them.
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Sulaiman
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a beautiful piece of glassware
may I suggest collecting berries this fall then ferment some wine
- to share with the glass worker.
PS nice thermometer - calibrated ?
CAUTION : Hobby Chemist, not Professional or even Amateur
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