JohnBee
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Raising pressure in vessel safety?
I'd been experiment with changing boiling points in solution and wondered what is considered safe in such cases?
So far I've only pulled a vacuum with a bell, but would like to try raising pressure so as to raise the boiling temps for observation.
That said, based on a chart I found, it looks as though I could expect to achieve aprox. 130c by raising vessel pressure to 40psi with water. However,
I'm a bit nervous in terms of safety as this is being done in a home setup and where the closest I've ever come to working with pressurized vessels
would be with pressure cookers and air compressors 
[Edited on 12-6-2015 by JohnBee]
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Sulaiman
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So get a pressure cooker and attach a thermometer / temperature sensor and a pressure gauge,
rely on the safety mechanisms of the pressure cooker.
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Loptr
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What sort of vessel would you put in the pressure cooker, or would the pressure cooker be the reaction vessel?
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blogfast25
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Standard pressure cookers only go up to about 15 psi (over pressure), that's about 121 C for boiling water. Not exactly an autoclave...
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JohnBee
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Quote: Originally posted by blogfast25  | | Standard pressure cookers only go up to about 15 psi (over pressure), that's about 121 C for boiling water. Not exactly an autoclave...
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Oh wow, I thought it was so much more than that. lol
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Sulaiman
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here is b.p. vs. pressure http://www.engineeringtoolbox.com/boiling-point-water-d_926....
to get 'interesting' results the required pressures are, in my opinion, significantly dangerous. e.g https://www.youtube.com/watch?v=BWkBFv6Gu6g
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zed
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Ummm. The question being..."How much pressure can the pressure cooker vessel, actually take?"
In general, the smaller the diameter of the vessel, and the thicker it's walls, the more pressure it can withstand.
I should think a smallish hefty-walled stainless steel pressure cooker, would stand up to at least several atmospheres of pressure. But, I would be
reluctant to bet my life on it.
Hydrostatic testing would increase my confidence. Not so much so, however, that I would hang out nearby, while "Real" steam pressure built up.
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blogfast25
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| Quote: Originally posted by zed | Ummm. The question being..."How much pressure can the pressure cooker vessel, actually take?"
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DON'T GO THERE!!!! 
The pressure limit isn't determined by the wall thickness or general strength of the vessel but by the SEAL. I 'blew out' a commercial pressure cooker
once by increasing the weight of the steam valve and pumping the vessel with compressed air: barely above the recommended 15 psi the seal blew out.
Imagine if that had been steam though: I could have been badly scalded!  
THINGS LIKE THESE ARE NOT TO BE TAMPERED WITH! If you're going to mess with pressure, at least do it with a certified apparatus, no less!
[Edited on 13-6-2015 by blogfast25]
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zed
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So there it is! You will have to improve the quality of the pressure cooker "Seal", or you will have no real opportunity to detonate that pressure
cooker of yours, and thereby shred yourself like a head of lettuce.
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szuko03
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There are two things that I hope to never lose my "fear" of, pressure and electricity. Only because that one time you make a mistake you realize it a
fraction of a second before you learn why you shouldnt have done it. I dont want to think "hmm that water leaking around the seal is odd maybe its a
bit to high..." and have that be the last thing i remember.
Obviously you were right to ask but pressure and electricity should only be "played with" in the proper equipment with full safety gear. If your lucky
you get 2 chances to get it right or you get burned or something. Its just not something I would bet my life with.
Chemistry is a natural drive, not an interest.
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Fulmen
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Do not underestimate the power of pressure * area. Something like a hobby compressor tank has more than enough stored energy to kill a man.
We're not banging rocks together here. We know how to put a man back together.
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