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Author: Subject: separatory funnel stopcock
spirocycle
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[*] posted on 13-10-2010 at 13:08
separatory funnel stopcock


I have a nice big 2000 mL sep funnel, but there is no stopcock in it.

I have tried looking for places that sell plain old stopcocks, but to no avail.

does anyone know where to look?

I'm not even sure what size I need
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peach
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[*] posted on 13-10-2010 at 13:11


Interlock usually make those in the UK. I'm not sure if they even have a website and I'm absolutely shit tired from painting for 12h, so you'll have to search.

Ask all the more custom glass blowers, e.g. United Glass in the US. They will either have something suitable or be able to grind one I expect.

You'll need the big and the small diameter, then work out which key size it matches up to.




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spirocycle
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[*] posted on 13-10-2010 at 14:17


thanks for that
PTFE is usually cheaper than glass no?
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peach
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[*] posted on 13-10-2010 at 15:16


Yep. If you know someone with a lathe, they can probable make you one in a few minutes.

Give it a wipe with some grease when you put it together, I've had both PTFE and glass jam. A glass one was virtually solid and needed banging on a surface over a few weeks to get it open. In fact, I had to put so much turning force on the key in the end I was expecting the arms to snap. Someone had already greased that one then left it sat on the shelf for months or years. Whatever they'd use must have dried out somehow, because it was tighter than a 16 year old.

[Edited on 13-10-2010 by peach]




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spirocycle
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[*] posted on 13-10-2010 at 16:48


I think I have a volumetric flask like that
it looks like somebody welded it shut though
and theirs a strange moist gel on the inside of the flask
I'm almost scared to open it, who knows what it is
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Magpie
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[*] posted on 13-10-2010 at 18:20


I have a Kontes pressure equalizing addition funnel for which I cannot find a stopcock. The body specifies a 2A size, which is smaller than a regular 2. One thing I have learned is that if the mating surface is ground it is for a glass stopcock, if it is fire polished smooth it is for a ptfe stopcock. My funnel is ground.

Another thing to check is the taper. In the US the glass plugs are 10:1, and the ptfe plugs use a 5:1 taper.

The number 2 indicates a bore of 2mm, I think.

There are vendors that will supply the stopcocks (except the one I need), it just takes some searching.




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mr.crow
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[*] posted on 13-10-2010 at 18:30


As far as I know glass and PTFE stopcocks aren't interchangeable. PTFE sockets aren't ground glass. Just remember to pop it when you are done using it.

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Rogeryermaw
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[*] posted on 13-10-2010 at 18:36


Quote: Originally posted by peach  


Someone had already greased that one then left it sat on the shelf for months or years. Whatever they'd use must have dried out somehow, because it was tighter than a 16 year old.

[Edited on 13-10-2010 by peach]


how long has it been since you had a sixteen year old? the way they act these days you can drive a truck through em with out hitting the sides at age 14!




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spirocycle
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[*] posted on 14-10-2010 at 11:30


^nice one
when I get the funnel in my workshop, i'll inspect it and make a purchase

what kind of price range are we looking at?
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peach
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[*] posted on 14-10-2010 at 15:47


I had a 14 year old just recently, at a game of scrabble. They won.



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