Org Prep Daily

July 26, 2011

Expanding liquids break closed vessels

Filed under: lab destruction — milkshake @ 2:05 pm

I had a dumb mishap today: A 100mL Schlenk storage flask with 1,5-cyclooctadiene shattered. When I distilled my COD by vacuum transfer this morning I filled the storage flask all the way to the top and then turned the teflon stopcock shut. There was no head space left in the flask; as the liquid warmed from about 10C up to room temperature it expanded enough to burst the glass.

Coincidentally, my colleague finished off a 20L jacketed glass reactor in a similar manner just yesterday – he was cleaning it after the experiment and the heating jacket was shut off, both the inlet and outlet valves were closed while the jacket was still filled with polysiloxane heat transfer fluid. When the reactor was rinsed with ambient water it suddenly shattered: a small temperature difference was apparently enough to cause the silicone fluid expansion in the jacket and there was no air bubble space nor a tubing attachment whereto the silicone liquid could expand. Looking back, this jacket over-pressurizing would not have happened if one of the valves was left open.

I suppose we proved that liquids are incompressible and expand with heat.

Link: The Great Boston Molasses Disaster

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