What is the lowest negative pressure that glass instruments can withstand?
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I need to conduct some pilot tests soon, requiring an absolute pressure of 6 kPa, which is around -95 kPa. I was wondering if it’s possible to use common glass instruments found in laboratories for this purpose Instruments such as three-neck flasks, round-bottom flasks, and those with ground glass joints. I’ve used a recirculating water vacuum pump to pump air out of round-bottom flasks before, and it seemed to work fine: lol. But I’m not entirely sure, so I’d appreciate some advice from everyone. Thank you!
A regular glass bottle doesn’t necessarily shatter when pumped once; it’s fine as long as nothing harmful is inside it. But when we pumped toxic and corrosive gases into such a bottle, it’s unclear whether the bottle shattered due to impact between its bottom and the operating surface or because of solid particles pressing on it – in any case, it broke, and someone almost died. Have you seen the filtration bottles used in laboratories? Those are much thicker than other instruments; with such high vacuum levels, their thickness should not be less than that of filtration bottles
There is a possibility of something bad happening. Be careful. We conduct experiments using vacuum distillation; the material has been crushed! Fortunately, no one was hurt!
For ordinary round-bottom flasks, we often carry out distillation at 140°C and 1 kPa (up to 500 Pa), with no issues. Be careful not to let the stirrer strike the bottle walls violently.