Curious incident while distilling ...

brixtonj · Fri Apr 29, 2005 3:12 am

Hi All !
A funny (?) thing just happend today whilst distilling sassy for the very first time.

I tried to use a water aspirator .. but the vacuum has hopelessly low . So I machined a detachable intake maniford for a Air Compressor I got (for automotive purposes ) Then took the vacuum line ...from there.. and the result is a awesome vacuum (gauge reads 30!) , with incredible power (vacuums up a 2 liter distilling setup in less than 1 second )

Well , I distilled 200 ml of Sassy.. and -as expected- crystal clear drops start to collect in the reciever .. at a recorded temperature of about 110 Cs (which indicates fairly good vacuum) .

and then .. while I am mesmerized..looking at the safrole-drops ... tryying to visualize them as pills .. , Smile

KABOOOOOOM !!!!!!!!

without any warning the whole thing make a big explosion , and literally explotes .
fortunately thre' were not any fire.. but lots of smoke , and glasses everywhere .
Of course most of my dstilling setup- was bust .

What happened ??

The fucking thermometer was SUCKED trhought the thermometer adaptor .. and then .. fall (free fall ) towards the 2000 ml RBF , hitting it in the middle , making it implote .. and then all the liquids vaporized when they contacted the heating mantle thing .

Had I used a vigreoux colum .. that would have stopped the thermometer , but ,as I didnt have one .. I just use a Leibig Condenser as a fractioning column , and that let the termometer hit just in the center of the base of the 2000 round bottom flask.

No funny at all , probbably around 150 Euros of damage , and even my neightbours asked about the noise , smoke , and that licourize odour (imagine safrole , heated at 100 , and spread by the whole room !! . Its gonna smell like that for eons.

Incredibly the receptor flasks survived .. (thanks to be clamped , the clamp and clip stopped the implosion somehow . So I have about 100 ml of safrole (mixed with broken glasses) ..

Well , hope this helps
BrixtonJ[/sup]

ApprenticeCook · DILLIGAF

crap... sorry man that sounds terrible....
Well what happened was your thermometer holder probably had a small leak and didnt hold it tight enough. The vacuum then pulled air through this small hole and eventually the thermo came loose and BOOM!@!#@#$!
Next time just make sure its all secure and the thermo is secure, i use lab thermos which have a rubber bit at the top that stop them sliding all the way through in situations such as these.
Also the vacuum is probly a bit to large capacity, pulling the 30"Hg in less than a seccond in a 2000mL setup would have put some stress on the glass, put a screwgate valve inline between the aspirator and setup so you can slowly open the screwgate and allow the vacuum to slowly evacuate the setup, less stress, no mess (hopefully).

RIP to lost safrole.
-AC

bio · Working Bee

What a drag and the first time. Live and learn just don't give up and be SAFE.

Almost happened to me once but luckily was standing there when it began to move downward. Grabbed it in the nick of time. Boy was my heart thumping.

Never saw one of those rubber thingys but try wrapping teflon tape rolled into string tightly around the thermometer so that it makes a lip which rests on the adaptor(no grease). Did it this way every since that day and gives some peace of mind.

Like AC said, increase vacuum very slowly, if you know what's good for you and before the heat goes on it's a good idea to valve off the system and do a leak check. Might have saved the goods doing that. I doubt a vig column would have stopped the thermometer.

thenewrunne · Chemically Balanced

DrugPhreak · Working Bee

Anyone ever try a hose clamp to increase the vacuum slowly?

thenewrunne · Chemically Balanced

IME - It's not so much the vacuum "starts fast" it's just that at a certain vacuum pressure whatever is the weak spot, will blow/slide etc.

For flasks to blow, I've always had mine blow at high oil bath temperatures (and poor borosilicate flask quality), I don't like distilling with vacuum over 150 celcius or so. This is probably just an artificial limit that I set, I have no knowledge as to at what temperature borosilicate glass starts to lose strength.

Also,of course, ensure that your stir bar is stirring at a STABLE speed/movement. The shockwave from the stirbar hitting the side of the flask is my most likely candidate for why the flask broke.

FlaAlchemist · Sat Apr 30, 2005 7:24 pm

Brixtonj,
Can you give more details on how you converted the air compressor into a vacuum source.
Very Happy

Thanx

brixtonj · Sat Apr 30, 2005 8:07 pm

Hi !!
I took a 3HP (2 KW) workshop air compressors . Its belt-driven , and of around 100 liters of air reservoir.

There's some kind of air filter , and that air filter is held by two screws. In my case , the

I had just machined a flat piece of metal ,with the holes at the same distance as the air filter does , so I can screw it to the compressor *instead* the air filter. There's a third hole (in the middle) where weld a 8 milimeter tube , and from that ... I got the vacuum.

Surprisingly the vacuum is AMAZING. Really , It scares me . I need something to control it .. *as I said it vacuums to 30 in faster than you can see the gauge!*

Imagine a 2000 Watts vacuum pump! .

The noise .. is much reduced (most noise in air compresors are made by the compressed air being pushed into the tank. In this case... as there's nothing to suck (safrole vapours , that is ) . It reduced drastically the sound level .. to an acceptable laboratory-level.

It does NOT heat (as the cylinder and the head are designed to withstand serious heating under normal operation) , and if there';s no air to compress (vacuum) It wont' heat-up neither.

The exhaust air.. is full with oil (as there's vacuum in the cylinder.. it somehow sucks the oil throiught the rings ) , so just keep an eye on the oil level.

The only trouble I had (appart from the funny termometer sucking) is that from time to time .. the compressor stops !! 'cos Its full !! .-there's some pressostate/electric switch to stop the engine after reaching the desired pressure (8 Kg/cm2). So I had to leave the end of the air -line open (with a spray-gun ,and the trigger kept pulling ).

I can post some piccies of the setup if they can help

Have a nice day.

Chaoslord · Wed Jun 22, 2005 7:13 pm

Ah Nice memories this brings back!

Vacuum distilling MDP-2-P in a 500ml 3Neck RBF

This was a very interesting day

First - I used a 29/32 plastic cap - after some time, before the ketone came out, the cap imploded on itself, so i stopped it, removed everything, and replaced it with a RUBBER corck

Second-
Oh joy

As soon as the ketone started to drip, BOOM, whe rubber cork was sucked in to the ketone

The cork then began to swallow like the devil himself was inflating it, but nothing
burst open (no glass broken), only a disgusting smell of burnt rubber, smoke, two
human hearts beating @ 130bps and a nice POP-BOOM-SPASH sound.

A tip - don't use 3 necks in vacuum distillation - I only used it cause i had no other available

P.S. Is it ok to use a silicon rubber with a hole as a thermometer adapter? when I use the rubben one the safrole tens to smell a bit of burnt rubber...