Sciencemadness Discussion Board

10 liter flask frozen joint

Mildronate - 21-8-2010 at 00:02

Yesterday i get 10 liter round botomm flash, but it has frozen joint :( with rotavap adaptor.

devongrrl - 21-8-2010 at 01:39

How about gently warming the joint area and trying to rotate the two halves of the joint ?

peach - 21-8-2010 at 05:02

I'd go with devongrrl's suggestion first, with a fan heater, hairdryer, hot air gun or some warm water out the kettle.

Failing that, there's the gently tap it option. I put a tea towel down on the edge of a surface to avoid the taps being too sharp, and it really does have to be gentle. Vibration can also help free things. I've used an electric toothbrush to open seized screws on boiler parts, and use one to get phase boundaries back in sep funnels or settle fine precipitates quicker; the effect can be dramatic. The same idea is used by investment casting jewelers and guys pouring huge amounts of concrete, to knock the air out and encourage settlement. A high power jelly sex toy would be even better for transmission of the vibrations and reducing the glass damage potential, among other things.

Next option, soak in warm water, the glass. It may take days or weeks for the joint to entirely free in warm water, if it's ever going to come out.

Unfortunately, unless the grease is skewing things, that looks remarkably similar to a taper I finally had to smash (after three weeks plus of trying everything I could think of); the ground surfaces have gone from opaque to transparent, meaning something is likely trapped in there (and solidified) or the tapers have fused.

If water fails (give a good while to have a go), try squirting some solvents into the joint and covering it to prevent evaporation. This may also take days or weeks, and multiple squirts... hu hu huh hu

You would seriously benefit from having some rough idea what was run through it last when choosing methods to open it again, even if they can only tell you generally what they were doing.

Essentially, the prime ingredient for free'ing these is a lot of patience. Purposefully set it aside and don't play with it too often... :P or you'll go overboard and it'll be in the wrong kind of bits in not a lot of time.

edit: 10l ffs? You sure that's going to be big enough? :D Another option is, leave it jammed and use the one already in there (but I'm guessing you want that ground taper back). Also, before you give up and get the screwdriver out, if the joint is very well jammed, you won't be able to 'chisel' the remaining bits of offending taper off after smashing the smaller part, making it the very last resort (the flask will probably be wrecked in the process).

[Edited on 21-8-2010 by peach]

Mildronate - 21-8-2010 at 05:05

I open it few minutes ago ;) i used wood stick like writen in this homepage this flash is realy nice i probably use it for destilations.

peach - 21-8-2010 at 05:09


That was a lot easier than it could have been.

Enjoy you're freshly liberated, gigantic, flask.


Mildronate - 21-8-2010 at 06:23

anybody else using large scale glasware?

[Edited on 21-8-2010 by Mildronate]

aonomus - 21-8-2010 at 06:37

I occasionally use 3-5L flasks at work, but usually when a joint freezes, I grab a rubber coated plastic stick, and tap the joint while rotating, never broken the glass by this method, always freed the joint. Its like the wood-stick option.

BromicAcid - 21-8-2010 at 07:07

I regularly use 22, 50, and 72L glassware. Usually if I have a frozen joint it hasn't sat for any real length of time. I put on cut resistant gloves, squirt a little acetone on the joint to get a grip, and give it my all, 9/10 times the joint comes out, the last time it breaks.

Mildronate - 21-8-2010 at 07:54

72L :o in home or in work?

peach - 21-8-2010 at 09:31

Quote: Originally posted by Mildronate  
72L :o in home or in work?

That's got to be work. If not, he'd be selling us the reagents.

What kind of 70+ litre flask are you working with? Reaction vessels?

rrkss - 21-8-2010 at 11:08

Damn, the largest flask I've worked with in my home lab is 1 Liter and that is for bulk solvent distillations. Normally I don't need to go above a 250 mL for my reactions.

BromicAcid - 21-8-2010 at 14:49

Yeah, that's at work. My largest flask when I was doing chemistry at home was 3 L I believe. I work in a 'small scale' lab and the largest thing we have is a 100 L precipitation vessel. 72L glassware is usually for reactions then we strip down and transfer to smaller glassware for final distillations. The advantage of large glassware is of course larger joints, with 72L glassware you can easily work with 45/50 joints which allows you to strip off your solvent lightning quick. Less than 2 hours to pull over 40 liters of solvent on a good day. It's amazing to have the variacs of three zones maxed out and have a pot temperature of <0°C :D