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Author: Subject: Vacuum glass implosion?
Tsjerk
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[*] posted on 17-7-2020 at 15:15


Erlenmeyer flasks can be heated just as well as round bottom flasks, I heated them to 300+ without problems. Just don't heat the tick walled ones designed to pull a vacuum on.
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Eddie Current
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[*] posted on 17-7-2020 at 15:43


Quote: Originally posted by SWIM  


You have, however, given us all a fine insight into your personality.

[Edited on 17-7-2020 by SWIM]


So you're one of those internet heroes that likes to go out of their way to provoke others and then attempt to hide behind the mob? I tend to ignore people who are under the delusion that they speak on behalf of everyone. Jog along knackers.

Quote: Originally posted by Tsjerk  
Erlenmeyer flasks can be heated just as well as round bottom flasks, I heated them to 300+ without problems. Just don't heat the tick walled ones designed to pull a vacuum on.


Indeed. It's amazing how some folks seem to have a problem with identifying the difference.

[Edited on 17-7-2020 by Eddie Current]
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RogueRose
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[*] posted on 17-7-2020 at 18:03


Quote: Originally posted by Heavy Walter  
Years ago, I evacuated a large dessicant, not knowing that the cover has to match exactly to the lid (grounded surfaces), I used a cover from other one.
I left the evacuated dessicant in a table, left the room and then the dessicant exploded filling the room with shattered glass.
Then I learned about stresses in glass... and recognized a lucky day!

[Edited on 4-6-2020 by Heavy Walter]


I'm glad you said something about this. I just did the math on a 12" desiccator and there is almost 1700lbs of pressure across the top of the unit at full vacuum! Even at -10psi its almost 1200lbs over the surface.
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Fyndium
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[*] posted on 17-7-2020 at 23:29


I used to heat erlenmeyer flasks directly on a hotplate at earlier era when I did chemistry. I had zero issues because I had zero cracks. Lucky me. That was also the time I pulled vacuum on flat bottom flasks. I eventually broke them all, with my clumsiness. I now always use heating bath.
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Fyndium
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[*] posted on 6-11-2020 at 06:53


Are glass frit filters designed to handle ordinary vacuum pump pressure differential? Does size matter, as is 1000mL filter as suitable as 100mL?
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paulll
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[*] posted on 6-11-2020 at 22:19


"Are glass frit filters designed to handle ordinary vacuum pump pressure differential? Does size matter, as is 1000mL filter as suitable as 100mL?"

I'm not sure what counts as,"ordinary," but I pull 50-100mmHg through mine quite a bit and it doesn't seem to care. Shame it's liable to be destroyed when I finally get around to making an inevitably somewhat clumsy attempt to get the graphite out of it.
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Fyndium
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[*] posted on 7-11-2020 at 01:18


Ordinary vacuum pumps easily reach from 32mbar to 0.1mbar vacuum of absolute pressure in my books. I have used hand primer pumps, but they are somewhat PITA when dealing with larger amounts and especially when drying stuff on a vacuum, so just using a pump is much more convenient. I use to also increase the vacuum volume for example adding a chromatography reservoir between the filter and receiving flask so I need to apply vacuum only once and let the filter drain on it's own if it is a high resistance filtrate.

Piranha solution or nitric acid seem to be good carbon removers. I just cleaned one frit from carbonous residue with hot HNO3 after filtering nitrites from thermal reduction. I'm not that afraid of clogging my filters, even CaSO4 is soluble in cold water up to 2g/L so pulling lots of water through a filter quickly de-clogs it and pretty much all other stuff can be consumed by some chemical.

I always pre-heat my filters with warm water, then hot water and if necessary, finally with boiling water if I need to filter something hot. I've broken one filter when drying it in oven and I'm afraid that it does it again if I dump hot liquid into one. The frit is not as tough as borosilicate glass for thermal shock.
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paulll
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[*] posted on 7-11-2020 at 12:00


Makes sense.

Piranha's the plan but it's going to take me a while to get to the big distillation so I'm trying to be patient and not go down the oven route for the reasons you mentioned.
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Fyndium
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[*] posted on 8-11-2020 at 12:36


For drying filters (and all other glassware if in hurry and no oven), I nowadays rinse them with little acetone and pull air through. It gets them dry in a minute.

A good trick I learned just yesterday when cleaning a filter is to invert a hand primer pump and carefully squeeze air backwards through the filter. It creates a very fine curtain of bubbles and agitates the liquid, and this should be good at dislodging some non-soluble crap and for leaching low solubility stuff into the fluid.
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[*] posted on 28-11-2020 at 11:37


Quote: Originally posted by beerwiz  
It happened to me in the early days during my first vacuum distillation. I taped the flat bottom flask as a precaution, then when I pulled the vacuum, it imploded. Apparently, you should not pull a vacuum on flat bottom flasks. The tape kept the implosion at bay and no shrapnel was generated.

Wow... glad I ran across this. I was planning on doing [my first] vacuum distillation, and the receiving flask is a flat bottom boiling flask... lol.

Thanks!
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Fyndium
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[*] posted on 28-11-2020 at 13:53


I always wonder how NurdRage can hold on his erlenmeyers when doing vacuums. One would expect them to implode on a routine basis.
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