LuckyWinner
Hazard to Others
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Registered: 27-8-2018
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Glassware is Slowly Breaking under Vacuum... Safety?
i got some cheap but branded glassware.
probably is from china and just received a company logo from the distribution company.
boro glass 3 heat resistant.
Im using a weak vacuum pump to a max of 60mmhg , water boils at around 39C.
it starts by weird glass cracking sounds, but no visible cracks during the vaccum.
once the vacuum cycle gets finished the whole joint breaks quite easily just by touching it...
its always breaking at the base, below the joint.
latest unit that broke is my receiving flask.
used silicone vacuum grease on the upper part of the joint and do a couple 360* spins.
-am I doing something wrong apart from not buying high quality lab glass?
-i there a chance of implosion?
I can not find any data about this online.
[Edited on 21-2-2019 by LuckyWinner]
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phlogiston
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Location: Neon Thorium Erbium Lanthanum Neodymium Sulphur
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I'd definately consider the possibility of an implosion. Better be safe than sorry. Shrapnell from an glassware implosion is pretty scary, even
without chemicals.
I'd guess the most probably cause is defects in the glass. It may not have been annealed properly. If I understand you well, the spot where it breaks
is the joint has been attached. Without annealing, the glass will have internal strains and is likely to develop cracks.
Maybe someone more knowledgeable about glassware , but it might be possible to fix by heating/re-annealing.
Can you post any pictures? Also of your setup, eg showing how do you clamp your glassware?
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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LuckyWinner
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just clamping it with the red clamps at the joint not too tight not too loose.
one piece of glassware , an adapter to a funnel broke under vacuum without any clamps or attachments.
i just heard the crackling sounds. didnt see anything, once touched it just feel down, split in the middle.
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morganbw
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I think you just have gotten a hold of some glassware that is defective at the weld joints. Possibly due to improper annealing.
I am for sure not an expert but that is my take.
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woelen
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Thread Moved
23-5-2019 at 11:42 |
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