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United States8519 Posts
This afternoon I was in Physical Chemistry lab. About two-thirds the way through the lab, none of the balances will tare (ie, set a new zero). They were also drifting like crazy... a tenth of a gram every minute or two. Every single analytical balance out of like 10, none of them worked. My lab partner and I said screw it, something is wonky. We didn't need to be that quantitative, so we just guessed how much reagent we had based on previous trials. I threw out the possibility of small earthquakes causing the balances to shift.
Well, about 10 minutes later a hood goes off in the nearby stockroom. And then one in our lab, one in the instrumental lab across the hall, and then every single hood in the hallway goes off. I'm beginning to think a somewhat large but localized electromagnetic field is screwing with the electronics. The thing is, the lights, computers, spectrometers, and pretty much everything else electronic was working fine.
Since all the hoods were on full blast, the ventilation system failed due to overload. This created an enormous pressure difference from the outside of the building to the inside... anytime anyone would open a door, wind would blow in. It managed to blow cigarette smoke from the second floor down to the first floor... traveling close to 100 feet, minimum.
So yeah, that's my somewhat exciting day in lab. 
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This is why fume hoods are supposed to be kept closed, or as close to closed as possible at all times.
Also saves on your electricity bill : D
But wow, that's pretty cool.
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Got a huge magnet somewhere in the building?
I want to believe it's something like a gas leakage that tripped the hood sensors, and the resulting pressure fluctuations from the pumps were registering on the balances...
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United States8519 Posts
The only real magnet that I'm aware of is the electro-magnet in the NMR, but that is heavily shielded (ie, you can be within a foot of it and it won't wipe your credit card) and it wasn't even being used at the time. Also every hood was already closed (except the one I was working in). The only gas that I'm aware of is the methane and compressed air that are hooked directly into the hoods, and I would suspect they would make noise if they leaked to any substantial degree.
Also the balances are in their own room, so even if there were massive leaks, I'm not sure how that could mess with the balances, which all have windows. Even the rather large air currents that flow through the room on a regular basis don't cause the balances to drift that much (and closing the windows usually kills 99% of that), and they always tare, even if it's slow. Except that annoying balance in the corner which never works for me.
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EPT
