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Author: Subject: Had a small fire in the lab this evening... was making ether of all things.
evil_lurker
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[*] posted on 23-9-2006 at 21:38
Had a small fire in the lab this evening... was making ether of all things.


One of my ventilation fans motors shorted out and caught on fire while making some ether this evening.

Luckily I was in the lab at the time and got it unplugged and tossed out the door before it managed to catch anything else on fire, or worse, cause an explosion.

Wanted to tell this to everyone in hopes of reminding them of good lab safety practices.

Never leave a still unattended, especially when distilling an extremely flammable solvent. Always keep a fire extinguisher handy. Store your chemicals some other place than your lab. Know where your circuit breaker is in case you need to kill the power quickly. Have a plan of action formulated before you perform a reaction in case something goes wrong. Last but not least, don't use old cheap fans in your lab.

All's well that ends well, but still it about scared the poop outta me. :P
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guy
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[*] posted on 23-9-2006 at 23:44


Why not do it outside?



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evil_lurker
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[*] posted on 24-9-2006 at 11:46


I prefer to work indoors whenever possible for several reasons.

Convenience is the main one... I don't have to drag all my stuff outside, set it up, then when I get done tear it all down and drag it back inside.

Weather is another reason, at the time it was raining off and on all evening and would have gotten dark several hours before I could have finished up.

Privacy is the other... chemists are somewhat treated with suspicion around these parts, if it was any other reaction I wouldn't give a darn.
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mericad193724
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[*] posted on 27-9-2006 at 15:10


I have been thinking about getting a small fire extinguisher for my lab (AKA garage). There small extinguishers are cheap $15 USD, but the kind I saw at my local hardware store is CO2.

What is the best type of extinguisher to get for a lab, Dry chem?, there are a bunch of different kinds.

My thinking is that lab fires could just as easily start with oxidizers (KMnO4, KNO3, chlorate, etc.) we all have laying around, and I don't think CO2 will help much for those.

Mericad
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[*] posted on 27-9-2006 at 15:23


Problem is, with metal powder fires, you make things worse if you use water, or even dry extinguishers that use chlorinated carbons. Once a fire of metal powder gets going, particularly in presence of oxidisers, you are in trouble regardless.
Same goes for water on solvent fires, they just spread it because of its greater density, by making solvents spread since they float to the top.
Best is truly just to store it outside. For that reason, all oxidisers, acids and non-freezable solvents I have, are outside. I sleep better now :)




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not_important
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[*] posted on 27-9-2006 at 20:08


Chlorocarbon extinguishers are pretty rare, Dow has some newer fluorocarbon ones. Most dry extinguishers in Western countries use carbon dioxide, BC sodium or potassium bicarbonate, ABC - ammonium sulphate and/or ammonium phosphate, or 'purple-k' - potassium bicarbonate treated with silicones and mixed with a bit of clay and silica to make it water-proof and free flowing. Used on class B fires, flammable liquids.


As an side note, the relatively new agent PhostrEx is PBr3 with a propellant. Don't use on metal fires, but perhaps direct into a flask...
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[*] posted on 28-9-2006 at 03:39


Kinda pricey but Halon is best all around and
good for electrical fires. In fact that is what is used in substation transformer rooms.

Also available in small canisters for boaters. Nothing like a fire on a floating fuel tank.

since Halons displace oxygen you would probably suffocate before the fire killed you
if you stayed in the room (lab) without
breathing apparatus.

When commissioning a large Halon (BTM in
UK) system with CO2 in a 250 bottles (full size industrial) the engineers had scuba gear ready to view and video the discharge and old Joe said nahh, "I will stay in the parking lot and watch the show."

Was kinda funny that day when the cameras began to roll and about 3 sec later
water condensation caused a thick fog which ruined the video. But old Joe
almost laughed when they told him to call the ambulance. Seems the chief mechanical engineer for the consultant fell thru the raised floor in the computer room due to a missing tile and the fog. Laden with scuba gear he fell halfway in and broke his leg in the cable tray below. He never did like the
Chief 'cause he tried to crush every change order as a matter of some twisted principle
that he or his company could do no wrong and even tried to make old Joe pay for the
rented scuba sets, 11 of them, IIRC as part of the contract,

Serves him right, he thought to himself, but
wasn't about to pay for the breathing apparatus. See Joe was the construction manager in those days and hated having to go to court constantly because Prima Donna
consultants thought their designs were always perfect
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not_important
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[*] posted on 28-9-2006 at 06:56


Halon 1211 and Halon 1301 are banned by the Montreal Protocol, and rather difficult to obtain in most countries. Their kin the HCFC and HFC are very effective greenhouse gases, the colonise-Mars crowd was nts to use them to warm up Mars; one year of bad storms here may lead to the inclusion of HCFC and HFC in the ban.
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[*] posted on 2-10-2006 at 12:03


A properly designed Halon system doesn't displace oxygen that much - and certainly not to the point of asphyxiation.

In fact a room protected by Halon is considered "life safe" when the proper concentration levels are used.

Halon actually interrups the chemical chain reaction of the fire itself (chain breaking) rather than removing the oxygen source. It is by far one of the best fire supression compounds ever invented.
Some of it's decomposition compounds can be rather nasty in certain curcumstances though.
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[*] posted on 15-10-2006 at 04:20


Interesting, I recently found a 0.9kg yield Halon 1211 (BrClF<sub>2</sub>C) extinguisher in the back of my car. I think I might keep it in my lab down at the 'farm' for extinguishing fires. According to weighing, it hasn't leaked and I assume the mechanism still works. Unless anyone has any stellar suggestions for some Halon? :D



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BeanyBoy
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[*] posted on 26-3-2007 at 07:47
Halon Survivable


We had a Halon Fire Supression System at the first datacenter I worked at, back 1979-1982. Two huge steel spheres full of it.

They had to test it once a year, which used up the existing Halon, after which they'd recharge it. The sales & support people insisted it only displaced oxygen in combustion sources, not in lungs. I joined the rep and stayed in the computer room during the release, after having been given a pair of ear plugs to insert.

The room pressurized so quickly at the halon dump, that every open box of fanfold paper turned into a Jack-In-The-Box, and punch cards & other detritus went everywhere. The ear plugs were a definite necessity.

While standing there, the rep pulled out a book of matches, and struck them one by one, and we cheerfully watched them extinguish due to lack of oxygen.

The big joke was (before you'd seen the demo), that the gas was safe, but then the spheres exploded, the shrapnel would probably kill you...:o

-beany boy
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[*] posted on 26-3-2007 at 09:23


Lurker, thanks for the safety story. It is uncanny how, when something can go wrong involving ether, it will. It is a pity that explosion-proof fans are so expensive. Amateur scientists need to come up with their own... perhaps someone on a bicycle with a drive belt? :D

Beany, so that Halon fire suppression system would blow out your eardrums? Nice.

EDIT: Phosphor-ing, thanks for the tip. Never even thought of that.

[Edited on 26-3-2007 by Pyridinium]
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[*] posted on 26-3-2007 at 10:46


Explosion proof fans are not expensive. Bilge blowers for boats are made to vent the engine compartment of gasoline vapors. They cost somewhere in the neighborhood of $20-30 for a small one, but I haven't priced them in quite a while.
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[*] posted on 26-3-2007 at 12:17


....... It is a pity that explosion-proof fans are so expensive. Amateur scientists need to come up with their own... ....

The high cost of an explosion proof motor can be circumvented
by using a TEFC (Totally Enclosed Fan Cooled) motor in which
the stuffing box gland is a silicone sealed water tight fitting..

Explosion Proof electrical apparatus is intended to "contain"
an explosion and not to just "prevent"one. Prevention is
primarily accomplished by sealing conduits at both ends
vapor tight with a plastic type putty and special fittings.

12VDC bilge pump motors probably won't last long under continuos duty.
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[*] posted on 28-3-2007 at 04:15


From Ind Eng Chem 675 (1926):

To prevent sparks from the motor igniting volatile solvent fumes, the principle of the Davy lamp was applied. The air holes at the brushes were covered with 50 mesh copper gauze, welded on. The motor was then run free and under load in explosive mixtures of benzene, gasoline vapor and natural gas. No explosions occured, although the brushes were sparking badly. Under similar conditions the same unprotected motor invariably detonated the gas mixtures. It should be noted that this modification gives no protection from the improbable event of a spark between the shaft and bearings, but this is a rare occurance.

Brazing can be used to attach the mesh :cool:

[Edited on 28-3-2007 by leu]




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[*] posted on 28-3-2007 at 05:06


Quote:
Originally posted by Pyridinium
Lurker, thanks for the safety story. It is uncanny how, when something can go wrong involving ether, it will. It is a pity that explosion-proof fans are so expensive. Amateur scientists need to come up with their own... perhaps someone on a bicycle with a drive belt? :D

Beany, so that Halon fire suppression system would blow out your eardrums? Nice.
[Edited on 26-3-2007 by Pyridinium]


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