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Author: Subject: First Major Lab Accident
Dariusrussell
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sad.gif posted on 24-12-2014 at 07:37
First Major Lab Accident


I thought I should post this as a warning and a reminder. I know Keck Clips aren't good above ~150C, but a moment of stupidity lead me to use them in a benzyl alcohol synthesis.

[ DON'T USE KECK CLIPS ABOVE 150C


The one on the flask ended up melting and dripping onto the hotplate, promptly catching fire. My fume hood honestly saved me and some cleanup, as all I had was a powder type fire extinguisher.

Here are some pictures:










As you can see the inside of my hood is coated in powder. There is a fair bit of charring on my claisen, and the Rxn flask is pretty much done.
The accident was entirely my fault, no one got hurt, and the fire was promptly put out with minimal damage.

Happy (And safe) Holidays,
Darius
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Molecular Manipulations
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[*] posted on 24-12-2014 at 07:49


I hate those messy powder type fire extinguishers, CO2 is way better for a lab.
Consider yourself lucky, my first major fire was worse. Cracking lots of glass, buring reagent bottles (none contained flammables luckly) and doing lots of general damage, worst of all, I wasn't even there at the time, so it just burned itself out.
Be safe and buy a better fire extinguisher!;)
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Mailinmypocket
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[*] posted on 24-12-2014 at 08:04


How big can a burning keck clip fire get? I would have thought pouring sand on the glob of burning plastic would be enough?
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Zyklon-A
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[*] posted on 24-12-2014 at 08:19


I think the benzyl alcohol caught fire, which can burn if preheated.
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Dariusrussell
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[*] posted on 24-12-2014 at 08:21


Well probably not that big, but I had some flammable reagents in the hood, along with not wanting to deal with burning acetic anhydride. The keck clips also started burning up the clips on the reflux app, I also panicked a little.
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Mailinmypocket
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[*] posted on 24-12-2014 at 09:29


Always better to be safe rather than crisped ;)
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Dr.Bob
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[*] posted on 24-12-2014 at 09:41


Good reaction, as long as the fire is out, and no one is hurt, the clean up is not too bad. I once come on a large fire in a hood where 3 people were standing there just panicking and doing nothing but watching. That was the worst case, as there was a lot of solvent in the hood. The fire was out in 3-5 seconds of a fire extinguisher, and all was better, except for the cleanup and paperwork. But it could have been much worse.

Everybody have a safe and Merry Christmas!
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Magpie
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[*] posted on 24-12-2014 at 10:59


I've melted a few of those Delrin keck clips and broken many more. Never had one catch fire, however.

I've been so disappointed in the Delrin clips that I've been slowly changing over to those made of ptfe. They are more expensive but are a much stronger clip and are good for up to 200°C. VWR sells them (see photo below). They come in an Ace Glass package but I couldn't find them on Ace's website, which is somewhat cumbersome.

The Ace site did list a ss clip good for 500°C, however. I've been looking for those for a long time. See photo below.

Thanks for posting this. It may inspire me to install a fixed fire extinguisher system capable of shooting CO2 into my fume hood duct - something I've long thought of doing. I agree with you that a good fume hood draft is a great asset when you've got a smoky fire going.

ptfe clip.jpg - 5kB ss keck clip.jpg - 15kB




The single most important condition for a successful synthesis is good mixing - Nicodem
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CaptainPike
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[*] posted on 24-12-2014 at 12:41


Wow, thank God (or good old numerical probabilistic outcome) you were working in a fume hood. Thank you for reminding me how lucky I am and how I ought to do more to hedge my own insurance against disaster. There's more I could do, I will reconsider.

PS: there's nothing like wire & hooks, to be sure.



[Edited on 24-12-2014 by CaptainPike]
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[*] posted on 24-12-2014 at 13:33


Make sure to get the powder out of your heater/stirrer. It is very corrosive.



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macckone
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[*] posted on 24-12-2014 at 18:52


United glass tech carries metal Keck clips.
Look under glassware accessories.
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Magpie
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[*] posted on 25-12-2014 at 10:23


Quote: Originally posted by macckone  
United glass tech carries metal Keck clips.
Look under glassware accessories.


Yes, and at a much better price than Ace. Thanks.




The single most important condition for a successful synthesis is good mixing - Nicodem
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dermolotov
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[*] posted on 26-12-2014 at 22:27


Quote: Originally posted by phlogiston  
Make sure to get the powder out of your heater/stirrer. It is very corrosive.

This^^

It looks like a new hot plate/stirrer, too. Must've cost a lot. I have one of those older corning PC-420s before they were replaced by the PC-520s.
Mine has all sorts of war scars. The most annoying one is that the stirrer doesn't shut off at the 'off position'. I have to position it carefully between 8 and 9 for it to truly be off. Corrosion due to same reason.
Treat that as the most important piece of equipment in your lab! It sure is the most expensive!
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DJF90
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[*] posted on 27-12-2014 at 11:49


You should clamp your apparatus more securely, with clamps, not keck clips. That being said, at least no-one got hurt.
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[*] posted on 27-12-2014 at 13:51


Quote: Originally posted by DJF90  
You should clamp your apparatus more securely, with clamps, not keck clips. That being said, at least no-one got hurt.

x2. Good eye, mate.

Never have a keck clip hold onto a reaction vessel - ALWAYS clamp it with an all metal or cork clamp.
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forgottenpassword
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[*] posted on 28-12-2014 at 03:21


What is the intended application of Keck clips? Other than securing a flask to a rotary evaporator, I have never had occassion to use them. It looks like you're using them on EVERY joint?! Is it really necessary?
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Magpie
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[*] posted on 28-12-2014 at 10:47


You don't have to use keck clips. The object is to have secure joints. If all joints are securely in place and the pieces are held rock solid with clamps then you are good to go.

I like to use them for the following reasons:

1. I can form sub-assemblies and move them around without fear of them falling apart and breaking glassware.

2. With a good firm keck clip you can look at the assembly and be reasonably assured that the joints are secure, ie, they won't be leaking on you as the heating/reaction proceeds.




The single most important condition for a successful synthesis is good mixing - Nicodem
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forgottenpassword
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[*] posted on 28-12-2014 at 11:51


Yes, I can see the sub-assembly application. Putting a Keck clip on the reaction flask itself seems a misuse to me, though.

[Edited on 28-12-2014 by forgottenpassword]
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dermolotov
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[*] posted on 28-12-2014 at 12:25


Quote: Originally posted by forgottenpassword  
Yes, I can see the sub-assembly application. Putting a Keck clip on the reaction flask itself seems a misuse to me, though.

[Edited on 28-12-2014 by forgottenpassword]

Yupp. As seen, it's actually dangerous to do so.

If you need to use them, use those solid steel ones. Otherwise, simple lube with a set little clamp solves the problem.
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Magpie
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[*] posted on 28-12-2014 at 16:38


Quote: Originally posted by Magpie  
If all joints are securely in place and the pieces are held rock solid with clamps then you are good to go.


This statement may have been misconstrued. I meant that if all pieces are held securely in place by equipment clamps, not keck clips, then the assembly is ready to use.

Yes, if the environment of the keck clip is anticipated to be too hot for the clip, then of course, don't use one. A melted clip accomplishes nothing. I also usually leave one joint unclipped to act as a safety relief port in case the system becomes inadvertantly over-pressurized.




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macckone
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[*] posted on 30-12-2014 at 13:27


If something is going to be very hot then don't use the plastic coated equipment
clamps. They may help prevent breakage but those melt coatings and burn much
easier than keck clamps.
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adk
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[*] posted on 10-3-2015 at 02:21


Ouch. Definitely clean that powder from your equipment.

Try these: http://clipox.de

Stainless steel joint clamps. Better than Keck or any other plastic clamps :)

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[*] posted on 17-3-2015 at 15:23


Keck clips make it all Look good, which is surely worthwhile.

In my limited experience they appear to be pretty useless for any other purpose (e.g. holding ground glass joints together under any kind of pressure).




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[*] posted on 22-3-2015 at 20:46


Ouch! I bought a kit through College a while back and they provided the metal type of kek clips... It might be my OCD but I always make sure they fit tight and are always fitted!

Glad your ok though and you had the correct safety in place. "Don't try this at home"
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[*] posted on 4-4-2015 at 09:14


Wow... I am just getting into this whole amateur chemistry thing for the first time. I have 3 years of real organic chemistry at a major state university all that good stuff but for the first time in my life I have the money to invest. Anyway I hope to learn from mistakes like this so I dont make them. Thank you for taking the time to share your story.
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