Safe max temperature range for heating various borosilicate glassware?
1. You're using a burner to heat borosilicate glassware that's happily sitting on your favorite wire/ceramic pad. What's a safe temperature range (from measuring the contents?) to stay within to avoid a spectacular thermal shock display? (you know, *boom*)
2. How does this range change between light, medium and heavy duty glassware?
3. Assuming same duty, is there a difference in max safe temp between high and low quality glassware, i.e.Pyrex and Bomex? If so, what?
4. Do bubbles/external chips (not cracks, obviously) make glassware unsafe to heat, or should it just be used for lower temperatures? If so, what?
I ask because I've acquired two flasks of unknown history: A Pyrex #5340 500ml vacuum filtering flask with an air bubble in the neck, and a Bomex 100ml Erlenmeyer with an air bubble in the base. Mr. Bomex also has a ~1mm chip on the outside wall. Amazingly, all my other labware's flawless. So, I ask because I want to be safe. Thanks in advance!
Answer:
The Mr. bomex flask I would not heat at all. The chip in the glassware will make it very unstable and once you take it out and handle it you could break it very easily.
As far as borosilicate glassware, also known as pyrex is very stable at high temperatures. You would basically need to put it in a furnace to melt it. SO as long as you are using it for common lab practices it should be very safe.
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