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Author: Subject: Borosilicate under pressure?
low.safety.standards
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[*] posted on 21-9-2018 at 00:02
Borosilicate under pressure?


Hello people,

Do anyone know of work with pressurized glassware? I'm looking for something that could withstand 20 atm at a couple hundred degrees with some 250ml volume (working pressure would be around 10 atm). There's a guy in youtube exploding a wine bottle just under 250psi (~15 atm). Any idea on what I could use or what thickness should I ask the glass maker to make it?

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Sulaiman
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[*] posted on 21-9-2018 at 01:23


Should be OK provided that you have the correct PPE


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Deathunter88
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[*] posted on 21-9-2018 at 03:04


Just. No. Use something else like stainless steel.
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macckone
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[*] posted on 21-9-2018 at 09:03


Borosilicate is not pressure safe.
Champagne bottles will handle a lot of pressure but aren't thermal shock safe.
Stainless steel would be the way to go.

If you need to do a reaction at high pressure and stainless steel would corrode too badly, you can use PTFE coatings or a borosilicate apparatus inside of a stainless steel autoclave of some kind.

220+ psi is pretty high pressure for a home lab and using poorly designed apparatus may result in casualties.

For reference a champagne bottle is designed with a high safety factor and for an operating pressure of 90 psi. They are designed to be safe to 12 atms and possibly more depending on the bottle (some are rated higher). They will certainly handle more pressure than a wine bottle. A good champagne bottle should handle 220+ psi but see the above safety apparatus.

A stainless steel CO2 fire extinguisher should be the right item to hold that kind of pressure.
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Heptylene
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[*] posted on 21-9-2018 at 09:24


As proposed by macckone, you can place the glass reactor inside a stainless steel one. By using a liquid with the appropriate boiling point inside the stainless steel reactor you could mitigate the pressure the glass reactor is subjected to. The glass reactor will only "feel" the pressure difference between inside and outside.

For this to work you would need to make sure the intended reaction inside the glass reactor doesn't produce a lot of gasses, and you would have to heat and cool the whole thing slowly, such that the pressure differential between the inside and the outside of the glass reactor is minimized.

I've seen pressure glass reactor on ebay that are stated to work up to 6 bars. I wouldn't trust those on their own, but if contained inside a stainless steel shield they should be safe enough.

The gauge in the drawing show 3 pressure gauges: ambiant atmosphere, inside the SS reactor, and inside the glass reactor.

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low.safety.standards
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[*] posted on 21-9-2018 at 10:16


Quote: Originally posted by macckone  
a borosilicate apparatus inside of a stainless steel autoclave of some kind.


Quote: Originally posted by Heptylene  
The glass reactor will only "feel" the pressure difference between inside and outside.


Ingeniously simple solution! Part of the problem is corrosion, most of it is that I wanted to see inside :D

...but that can be achieved with a 1" polyurethane window on a CO2 fire extinguisher holding my "not pressure rated" borosilicate reaction vessel, thanks!

Anyway, also found https://www.schott.com/d/tubing/9a0f5126-6e35-43bd-bf2a-3499... which gives an approximate pressure rating equation for tubular glass given wall thickness and outside diameter.


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macckone
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[*] posted on 21-9-2018 at 10:35


If polyurethane is suitable for a containment vessel, you may be able to use a polyurethane tube and then use end plates attached with high strength steel. Not sure what thickness you would need for that pressure rating. Honestly I would go straight stainless with a camera inside.

If you are using a fire extinguisher you still need to get your reaction equipment inside, if you are using a test tube that should be easy. For a 500ml flask, not so much.
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[*] posted on 21-9-2018 at 11:51


Quote: Originally posted by macckone  
If polyurethane is suitable for a containment vessel


It's not, I meant it as a window for the pressurized autoclave containing the borosilicate glass.
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[*] posted on 21-9-2018 at 12:54


Look up "hydrothermal autoclave reactor" on eBay. The lowest grade ones withstand up to 3 MPa which is almost 30 atm. There are 6 MPa and even 22 MPa models, though much more expensive.

It basically a thick-walled stainless steel vessel with fine threads on one end and internal chamber made of PTFE or PP.

They come in variety of volumes from 10 mL to 500 mL.

Another (cheaper) option is a stainless steel pipe with threads on both ends. You can cover the threads with Teflon tape and tightly seal with caps.

[Edited on 21-9-2018 by nimgoldman]
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[*] posted on 29-10-2018 at 21:21


Can I ask what we’re you planning to do under such pressure?



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[*] posted on 29-10-2018 at 23:02


I've used thick-walled borosilicate pressure vessels at 150 °C and 10 bar pressure. I'm talking about something like this: https://us.vwr.com/store/product/4831644/pressure-tubes-with...

(They can also withstand 300 °C and 5 bar, but I'd be wary of using 10 bar at that temperature.)




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[*] posted on 30-10-2018 at 03:47


I've used Ace pressure tubes like these:

https://www.sigmaaldrich.com/catalog/product/aldrich/z564591

I used an oil bath to heat them. Even though they were rated for the pressure I was using, I put them behind a blast shield and attached them to the end of a rod on a pivot so I could dunk them and lift them out of the liquid without having to get behind the shield.




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[*] posted on 30-10-2018 at 10:09


Yes, a blast shield is highly advisable (and something which I forgot to mention in my post above!)

I've never had one explode, but I expect if the tube broke under pressure a powerful BLEVE would result.




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[*] posted on 27-12-2018 at 10:05


For 250 ml, a glass vessel is really pushing it, even for the Ace or Aldrich pressure tubes, and if you heat them, the rating goes down further. Just use a glass lined steel pressure reactor, they can handle that with little hazard, just have to be careful when opening them to vent them slowly. Even the best chemical microwave systems barely go up to those pressures and temps, typically only for 2-20 ml.
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