Sciencemadness Discussion Board

Stopcock replacement

sansos - 30-3-2018 at 22:23

Ive recently broken a stopcock for my sep funnel is there a cheap/easy way to replace it?

LearnedAmateur - 31-3-2018 at 00:05

In which way is it broken? Have you snapped off the stopcock part from the body or has the ‘barrel’ bit where the valve goes broken into several pieces. I’ve done both before, for the first I’ve managed to weld it back on with a blowtorch - I have a little bit of experience working with glass so if you don’t then try find someone who can do that for you, and it shouldn’t break again if you’re not subjecting it to high temperatures. If the second case has occurred, then unfortunately there isn’t anything you can do except finding an alternate uses for the broken funnel. You can’t use super or glass glue to fix it because organic solvents will just dissolve it and you’ll end up with a mess.

Dr.Bob - 31-3-2018 at 04:44

Is the small stopcock part itself broken, or the whole stopcock holder?

Is the stopcock PTFA or glass? What size is it?

It is hard to answer vague questions in a useful manner, please give some details or a photo if you want a useful answer.

sansos - 1-4-2018 at 13:51

Its the barrel of the glass stopcock, essientially I was wondering if I could go to a scientific glass workshop and order a replacement stopcock.


[Edited on 1-4-2018 by sansos]

Dr.Bob - 1-4-2018 at 16:09

It will cost more to repair than just buying another used one, maybe more than a new one. Unless you have a good friend who is a glass blower, repairs only make sense for custom, complex or pricey things. If it was the stopcock that was lost or damaged, that is replaceable, but the rest is hard to fix. Most sep funnels eventually get part of the drain tube chipped, cracked or broken off. If there is any bit left, they still work OK, usually. But if the stopcock area itself is damaged, there is little that can be done. That is the hardest joint to make, and requires a lot of skill to do without warping the stopcock.