Sciencemadness Discussion Board - Vacuum glass implosion?

Vacuum glass implosion?

Refinery - 3-6-2020 at 11:23

I was wondering if anyone has ever had a glass implosion during vacuum process? People speak about this often and I've been always vary of such event, considering the outcome would be absolutely catastrophic if flammable, possibly even toxic and boiling hot liquid is blasted into aerosol cloud and splashing everywhere and causing instant, massive fire hazard.

Apparently, vacuum strength is linear, although boiling point is reduced exponentially when pressure drops so glassware takes most of the stress at range where nothing actually happens, and those last few millibars matter a little in that aspect.

So, how high of a risk an implosion is, how to prevent it, and how to minimize catastrophic outcome IF such a thing occurs?

beerwiz - 3-6-2020 at 13:57

It happened to me in the early days during my first vacuum distillation. I taped the flat bottom flask as a precaution, then when I pulled the vacuum, it imploded. Apparently, you should not pull a vacuum on flat bottom flasks. The tape kept the implosion at bay and no shrapnel was generated.

Belowzero - 3-6-2020 at 21:54

I've witnessed such an event.
A fellow lab student left the vacuum open on a filtration erlemeyer and went for a break, it was a full sized lab and obviously used powerful pumps.

A loud crack/explosion was the result, sending glass all over the place. Luckily noone was close to the workbench , could have been messy.

[Edited on 4-6-2020 by Belowzero]

Heavy Walter - 4-6-2020 at 07:50

Years ago, I evacuated a large dessicant, not knowing that the cover has to match exactly to the lid (grounded surfaces), I used a cover from other one.
I left the evacuated dessicant in a table, left the room and then the dessicant exploded filling the room with shattered glass.
Then I learned about stresses in glass... and recognized a lucky day!

[Edited on 4-6-2020 by Heavy Walter]

Mateo_swe - 14-7-2020 at 09:40

I read that one should not use flat bottomed round flasks when using vacuum but never heard someone have any problems with this.
I had guessed that was something that was a problem in the past and nowadays the flat bottomed round flasks were made sturdy enough to handle lab vacuum.
But that is not correct i have understood now.
For using vacuum one should use real round bottom flasks, not the flat bottomed versions.
That makes me think about glassware of bad quality.
I have had several funnels and other glassware break while washing them and not from hitting them against something, just temperature and minor physical stress while wiping them dry.
I wonder how this Chinese ebay glassware i always buy will handle stronger vacuum, anyone have had any vacuum accidents using this cheap glassware?

Tsjerk - 14-7-2020 at 09:48

The only flat bottoms you can pull a vacuum on are the thick walled Buchner funnels designed for vacuum filtration.

Mateo_swe - 14-7-2020 at 10:48

Yeah, those are made for vacuum.
Its quite amazing how much strength the round shape adds to a structure.
I wonder if that was not the case, would birds lay cube shaped eggs?

morganbw - 14-7-2020 at 14:54

Quote: Originally posted by Tsjerk

The only flat bottoms you can pull a vacuum on are the thick walled Buchner funnels designed for vacuum filtration.

That is what I use. The vacuum I pull is not full though. Never any problems with vacuum filtration.

Eddie Current - 14-7-2020 at 15:28

Quote: Originally posted by Refinery

I was wondering if anyone has ever had a glass implosion during vacuum process?

Yes, during a vacuum filtration, not a distillation..

I incorrectly filtered a heavy precipitate with a 500ml B24 Erlenmeyer flask and a B24 fritted vacuum funnel w/nipple, instead of a 500ml B24 vacuum flask.

I identified the problem a couple of minutes after I had applied vacuum and attempted to shut it down, but ended up showered in reaction contents and shattered glass and had to immediately get under the shower.

Fortunately, I was not seriously injured.

It was an easy mistake to make, and the moral of the story is that you should label specialized flasks that look very similar to others.

[Edited on 14-7-2020 by Eddie Current]

draculic acid69 - 14-7-2020 at 17:38

Quote: Originally posted by Mateo_swe

Yeah, those are made for vacuum.
Its quite amazing how much strength the round shape adds to a structure.
I wonder if that was not the case, would birds lay cube shaped eggs?

Wombats do cube shaped poo.

violet sin - 14-7-2020 at 21:13

I got sprayed with some paste recently. Home made buchner on standard 1000ml erlenmeyer. The return line to vac comes out the stopper, not off the flask. Had as purchased catch bottle between the vac, but it was loosing too much vacuum at one joint to relieve the pasty mush of it's liquid. Anyhow after I took the catch bottle off, it was noticed how much more pull was realized and I was using bursts of vac and let off, vent for sure, repeat... Then got lost in thought... POP!! Titania/alumina with some PdCl₂ left it whizzed past me and on the wall, ceiling, floor.

The büchner itself is a (ok laugh if you will) cat wet food dish I perforated taped to the top of a 1$ store funnel. The tape separated and dish lurched down in then stopped abruptly.

1) Imploded make shift büchner
2) Prior to filtration, plenty of Pd dropping out, presumably from HCl loss over time (thumbnail looks upside down, picture is not)

The old surface mount monolithic capacitors and resistors do have stuff to relieve them of. This is like the fourth or fifth pull after leaving to digest repeatedly.

I was really glad to see only the funnel break as my hands were right there when it went, I was aware of the issue, I knew it needed to be feathered... And I spaced out for a sec talking to the misses as she went by. It was avoidable and a decent learning experience, only b/c it was without injury. Still had to clean splatter off the ceiling, walls, cupboard, sink and such. Paying attention is important

Refinery - 15-7-2020 at 04:11

I was scared when I saw Nurdrage used erlenmeyers for vacuum distillation.

Aren't erlenmeyers unsuitable for any sort of vacuum due to their flat bottom?

outer_limits - 15-7-2020 at 07:28

They aren't designed for vacuum. The only erlenmeyers that could be used are filtration flasks which were mentioned.

They are convenient to use on hotplate stirrer but somebody following directly his procedures could be damaged after implosion.

Refinery - 15-7-2020 at 10:16

I think implosion is not just a nuisance merely a joke, but absolute catastrophe that can put life in immediate danger. I don't really like the idea of any chemical spilling on me, and many chemicals are really nasty to be very conservative, starting from boiling acids to some very toxic stuff. Implosion type event will just burst the contents all around.

morganbw - 15-7-2020 at 13:51

Implosion is real, most never see it as they use proper vessels.
Physics is real, ignore at your own risk.

Eddie Current - 15-7-2020 at 13:57

Quote: Originally posted by Refinery

I was scared when I saw Nurdrage used erlenmeyers for vacuum distillation.

Aren't erlenmeyers unsuitable for any sort of vacuum due to their flat bottom?

It has more to do with glass thickness, and never place a vacuum flask under heat, they are not designed for this.

Erlenmeyers/flat bottom flasks are for reactions (cooling & heating), and non vacuum distillation.

Round bottom flasks are for reactions (cooling & heating), and vacuum distillation.

Vacuum flasks are for vacuum filtering only.

[Edited on 15-7-2020 by Eddie Current]

SWIM - 15-7-2020 at 15:09

Filter flasks are fine under heating.

In fact, its hard to imagine how anyone could possibly think otherwise.
It just makes no sense whatsoever.

Do you have an actual source for this or did you just make it up?

S.C. Wack - 15-7-2020 at 15:25

"Thick walled glassware, such as jars, bottles, cylinders and filter flasks, should never be heated on hot plates."

Care and Safe Handling of Laboratory Glassware

Eddie Current - 15-7-2020 at 21:17

Quote: Originally posted by S.C. Wack

"Thick walled glassware, such as jars, bottles, cylinders and filter flasks, should never be heated on hot plates."

Care and Safe Handling of Laboratory Glassware

This is further complicated when pressure is added to the equation.

Can you heat them somewhat? Sure.

Is it a good general practice? No.

http://www.vidrasa.com/eng/products/duran/duran_pf.html

[Edited on 16-7-2020 by Eddie Current]

Mateo_swe - 16-7-2020 at 08:24

I often use flat bottomed round flasks for vacuum filtration with fritted funnels that has vacuum nipples.
But i use quite weak, cheap little pumps for these filtrations that doesnt make very strong vacuum.
It has crossed my mind that its not optimal and one can have an accident, but the flat bottomed flasks seem quite robust and the pump quite weak.
I have a ceramic buchner with a real earlenmyer filter flask but this is a quite large setup so i often use the fritted funnels with ordinary flasks for vacuum filtrations.
Maybe i should only use the round flasks for this in the future.
The risk for implosion is bigger with larger flasks i think.

SWIM - 16-7-2020 at 13:13

Quote: Originally posted by Eddie Current

Quote: Originally posted by S.C. Wack

"Thick walled glassware, such as jars, bottles, cylinders and filter flasks, should never be heated on hot plates."

Care and Safe Handling of Laboratory Glassware

This is further complicated when pressure is added to the equation.

Can you heat them somewhat? Sure.

Is it a good general practice? No

http://www.vidrasa.com/eng/products/duran/duran_pf.html

[Edited on 16-7-2020 by Eddie Current]

Thick walled flasks used for filtering are fine for heating just like thick walled RBFs and thick walled Erlenmeyers.
All thick walled, and all fine for heating.

If you actually believe you can't heat a thick walled flasks, then why do you have such a boner over even thicker walled reaction vessels? Do you yearn for one so you can not heat it? Got a lot of room-temperature chemistry you wanna try on a big scale?

Why do you think anybody would manufacture 24/40 joint Erlenmeyer reaction flasks if they couldn't be heated? More room temp chem?

The quote you posted also makes no reference whatsoever to the safety of heating filter flasks.

So here's a nice exercise in communications skills for you:
Can you analyze the sentence you posted and figure out what it actually says?

S.C. Wack - 16-7-2020 at 14:58

It's well known that the thicker the glass the more thermal stress. If one has a heat source at say 150C and a container of liquid at 25C, above a certain thickness it will crack. Annealing thick glass properly takes a long time.

Eddie Current - 16-7-2020 at 15:26

Quote: Originally posted by SWIM

Quote: Originally posted by Eddie Current

Quote: Originally posted by S.C. Wack

"Thick walled glassware, such as jars, bottles, cylinders and filter flasks, should never be heated on hot plates."

Care and Safe Handling of Laboratory Glassware

It's a thread about vacuum implosions.

Go and waste someone else's time with your repetitious mindless dick sizing.

It's boring.

SWIM - 17-7-2020 at 14:23

Is there something seriously wrong with you?

You say something inaccurate and expect it to stand because its not the subject of the thread?

I'm sure having to actually be accurate must be boring for you, but maybe you'll get over that some day.

You have, however, given us all a fine insight into your personality.

A word of honest advice: You might want to avoid doing that too often.

A filter flask is suited to heating like a Lamborghini is suited to plowing a field.

It works just fine, like it was built for it.

[Edited on 17-7-2020 by SWIM]

outer_limits - 17-7-2020 at 14:40

Quote: Originally posted by SWIM

If you actually believe you can't heat a thick walled flasks, then why do you have such a boner over even thicker walled reaction vessels? Do you yearn for one so you can not heat it? Got a lot of room-temperature chemistry you wanna try on a big scale?

You can do everything you want but sometimes the consequences could be bad. Erlenmayer flasks shouldn't be heated strongly and it is caused by their shape. Their thermal expansion is not uniform so they are prone to breaks.

Tsjerk - 17-7-2020 at 15:15

Erlenmeyer flasks can be heated just as well as round bottom flasks, I heated them to 300+ without problems. Just don't heat the tick walled ones designed to pull a vacuum on.

Eddie Current - 17-7-2020 at 15:43

Quote: Originally posted by SWIM

You have, however, given us all a fine insight into your personality.

[Edited on 17-7-2020 by SWIM]

So you're one of those internet heroes that likes to go out of their way to provoke others and then attempt to hide behind the mob? I tend to ignore people who are under the delusion that they speak on behalf of everyone. Jog along knackers.

Quote: Originally posted by Tsjerk

Erlenmeyer flasks can be heated just as well as round bottom flasks, I heated them to 300+ without problems. Just don't heat the tick walled ones designed to pull a vacuum on.

Indeed. It's amazing how some folks seem to have a problem with identifying the difference.

[Edited on 17-7-2020 by Eddie Current]

RogueRose - 17-7-2020 at 18:03

Quote: Originally posted by Heavy Walter

Years ago, I evacuated a large dessicant, not knowing that the cover has to match exactly to the lid (grounded surfaces), I used a cover from other one.
I left the evacuated dessicant in a table, left the room and then the dessicant exploded filling the room with shattered glass.
Then I learned about stresses in glass... and recognized a lucky day!

[Edited on 4-6-2020 by Heavy Walter]

I'm glad you said something about this. I just did the math on a 12" desiccator and there is almost 1700lbs of pressure across the top of the unit at full vacuum! Even at -10psi its almost 1200lbs over the surface.

Fyndium - 17-7-2020 at 23:29

I used to heat erlenmeyer flasks directly on a hotplate at earlier era when I did chemistry. I had zero issues because I had zero cracks. Lucky me. That was also the time I pulled vacuum on flat bottom flasks. I eventually broke them all, with my clumsiness. I now always use heating bath.

Fyndium - 6-11-2020 at 06:53

Are glass frit filters designed to handle ordinary vacuum pump pressure differential? Does size matter, as is 1000mL filter as suitable as 100mL?

paulll - 6-11-2020 at 22:19

"Are glass frit filters designed to handle ordinary vacuum pump pressure differential? Does size matter, as is 1000mL filter as suitable as 100mL?"

I'm not sure what counts as,"ordinary," but I pull 50-100mmHg through mine quite a bit and it doesn't seem to care. Shame it's liable to be destroyed when I finally get around to making an inevitably somewhat clumsy attempt to get the graphite out of it.

Fyndium - 7-11-2020 at 01:18

Ordinary vacuum pumps easily reach from 32mbar to 0.1mbar vacuum of absolute pressure in my books. I have used hand primer pumps, but they are somewhat PITA when dealing with larger amounts and especially when drying stuff on a vacuum, so just using a pump is much more convenient. I use to also increase the vacuum volume for example adding a chromatography reservoir between the filter and receiving flask so I need to apply vacuum only once and let the filter drain on it's own if it is a high resistance filtrate.

Piranha solution or nitric acid seem to be good carbon removers. I just cleaned one frit from carbonous residue with hot HNO3 after filtering nitrites from thermal reduction. I'm not that afraid of clogging my filters, even CaSO4 is soluble in cold water up to 2g/L so pulling lots of water through a filter quickly de-clogs it and pretty much all other stuff can be consumed by some chemical.

I always pre-heat my filters with warm water, then hot water and if necessary, finally with boiling water if I need to filter something hot. I've broken one filter when drying it in oven and I'm afraid that it does it again if I dump hot liquid into one. The frit is not as tough as borosilicate glass for thermal shock.

paulll - 7-11-2020 at 12:00

Makes sense.

Piranha's the plan but it's going to take me a while to get to the big distillation so I'm trying to be patient and not go down the oven route for the reasons you mentioned.

Fyndium - 8-11-2020 at 12:36

For drying filters (and all other glassware if in hurry and no oven), I nowadays rinse them with little acetone and pull air through. It gets them dry in a minute.

A good trick I learned just yesterday when cleaning a filter is to invert a hand primer pump and carefully squeeze air backwards through the filter. It creates a very fine curtain of bubbles and agitates the liquid, and this should be good at dislodging some non-soluble crap and for leaching low solubility stuff into the fluid.

SuperOxide - 28-11-2020 at 11:37

Quote: Originally posted by beerwiz

It happened to me in the early days during my first vacuum distillation. I taped the flat bottom flask as a precaution, then when I pulled the vacuum, it imploded. Apparently, you should not pull a vacuum on flat bottom flasks. The tape kept the implosion at bay and no shrapnel was generated.

Wow... glad I ran across this. I was planning on doing [my first] vacuum distillation, and the receiving flask is a flat bottom boiling flask... lol.

Thanks!

Fyndium - 28-11-2020 at 13:53

I always wonder how NurdRage can hold on his erlenmeyers when doing vacuums. One would expect them to implode on a routine basis.

Fyndium - 17-2-2021 at 10:54

I came up with this video when googling about the subject.

https://www.youtube.com/watch?v=c4VdSuU8TC0&

It seems that glass is phenomenally resistant against implosion even when seriously scratched, if it's compressive structural integrity remains rigid. Even when they actually made a crack in the glass, it held up.

The final outcome is very violent, though, so when it goes off, you'd better be prepared. To that, add 200C flammable, possibly toxic liquid splashing everywhere.

I'm sort of more confident pulling vacuum on my chinese flasks, but still the potential for implosion haunts me.

Fyndium - 28-2-2021 at 09:13

What would be the burst pressure of rbf, for example immersed in sea? How many atm would it take to collapse the flask from static pressure? This also correlates to safety factor for normal vacuum use.

Grizli7 - 1-9-2021 at 12:40

The root cause is "resistance of materials" is an applied science that all students hate. The fact is that a ball as a geometric figure works best for compression, therefore, stresses are evenly distributed in a round flask.
The quality of glass, its thickness, chemical composition are all secondary factors, first of all, the uniform distribution of stresses.
To understand better, do a simple experiment. Take a raw chicken egg, clasp your fingers, set the egg so that one end rests on one palm, and the other on the other, and try to squeeze the egg. Be surprised.

FluoroPunch - 23-10-2021 at 04:36

Quote: Originally posted by S.C. Wack

"Thick walled glassware, such as jars, bottles, cylinders and filter flasks, should never be heated on hot plates."

Care and Safe Handling of Laboratory Glassware

I can attest to this personally from practice. I once used a very nice thick walled 1L vacuum flask for heating since at the time it was my largest flask.

I was reacting HCl and some Fe nails to make FeCl₂ and crystals started to precipitate before the metal all had been digested. The volume was too large for my other flasks so I decided to use the vacuum flask. Big mistake. After maybe 15 or 20 min I believe I heard a crack and noticed a fairly large crack formed on the side close to the bottom. I immediately removed from heating and fortunately had no leak.

So no, I do not believe it is a good idea. Vacuum flasks have thick walls to withstand physical stress, which unfortunately due to greater thickness means greater thermal expansion & thus greater stress. Pulling vacuum on a flask stressed by heat adds even more stress due to the geometry of the flask i.e. conical, vs round bottom flask, which has better distribution of stress. This is the unfortunate catch 22 of glassware: you make it thick, its great for banging around and vacuum, you have it thin and its better for heating but physically weaker.

(I should add that the flask was old, donated to me from a lab I worked at and did have some surface imperfections.)

[Edited on 23-10-2021 by FluoroPunch]

S.C. Wack - 23-10-2021 at 08:19

Quote: Originally posted by Fyndium

It seems that glass is phenomenally resistant against implosion even when seriously scratched

I assume that this glass is all rounded surface, and isn't thick glass with a flat surface being heated or cooled?

This shows specific conditions needed for heating and cooling empty glassware:

SIMAX Glass Thermal Properties

High resistance of products made of SIMAX glass to sudden temperature variations – heat resistance – is given by a low coefficient of mean linear thermal expansion, relatively low modulus of elasticity in tension (E) and relatively high heat conductivity.

In cooling down and heating a glass product, an undesirable internal stress formation occurs. Cracking may occur in quick cooling down, if the undesirable internal stress exceeds the admissible limit. Simax glass products‘ values of resistance (D 0C) to a heat shock, depending on the wall thickness, have been specified in the below table:
Wall thickness (in mm) Resistance to a heat shock (D °C)
1 303
3 175
6 124
10 96

SIMAX Glass Annealing

Annealing represents a thermal process, the purpose of which is preventing the formation of undesirable and unadmissible high thermic stress inside glass, which could decrease the product resistance, and, eventually, removing the already formed stress.

The annealing cycle consists of three stages:

The temperature rise (product heating) at a heating speed from the inlet temperature to the upper limit annealing temperature.

Dwell on temperature (annealing, tempering, stabilization) of a product for a certain time at the upper limit annealing temperature, when temperature variations inside the product must be equalized and the stress decreased to an admissible limit.

Temperature drop (annealing and after-cooling) of a product at an annealing speed from the upper limit annealing temperature to the lower limit annealing temperature (this period is essential, as constant stress may be formed) and from the lower limit annealing temperature to the final temperature or up to ambient temperature (which is important for the product subsequent practical handling).

Specific annealing cycle is mentioned in the below table.
Range of Temperature
Rise Dwell Temperature Drop
Maximum wall thickness 20 - 550 °C 560 °C 560 - 490 °C 490 - 440 °C 440 - 40 °C
3 mm 140 °C/min 5 °C/min 14 °C/min 28 °C/min 140 °C/min
6 mm 30 °C/min 10 °C/min 3 °C/min 6 °C/min 30 °C/min
9 mm 15 °C/min 18 °C/min 1,5 °C/min 3 °C/min 15 °C/min
12 mm 8 °C/min 30 °C/min 0,6 °C/min 1,6 °C/min 8 °C/min

Fyndium - 12-11-2021 at 01:49

Round bottom flasks are the only type I would subject to vacuum. The exception I have been using are erlenmeyers (2L and 5L so far) for vacuum filtrations with small membrane vacuum pumps that generate only fraction of vacuum, in order of 10-30%, but these flasks are and will never be heated or otherwise disturbed. If I need higher power vacuum, I switch the receiver flask to a round one, and use my rotary pump.

I'm extremely scared of heating any glass with direct hotplate or flame nowadays. I just don't do it without a heating bath. Heating baths are also different, a metal shot bath would be close call to ordinary hotplate, but liquids that are oil or water based are good to go. Their downside is limited temperature, 150-200C stable max, but other option is to up the vacuum to make stuff boil at lower temps. When the glass is placed in a bath with thermal gradients far below 100C, thermal stress should remain within spec, unless a very thick walled or non-round glass is used.