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Dariusrussell
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Registered: 27-6-2013
Location: Southie
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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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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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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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I think the benzyl alcohol caught fire, which can burn if preheated.
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Dariusrussell
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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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Always better to be safe rather than crisped
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Dr.Bob
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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
lab constructor
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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.
 
The single most important condition for a successful synthesis is good mixing - Nicodem
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CaptainPike
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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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phlogiston
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Make sure to get the powder out of your heater/stirrer. It is very corrosive.
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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macckone
Dispenser of practical lab wisdom
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United glass tech carries metal Keck clips.
Look under glassware accessories.
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Magpie
lab constructor
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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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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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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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dermolotov
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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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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
lab constructor
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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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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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| 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
lab constructor
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| 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.
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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.
The single most important condition for a successful synthesis is good mixing - Nicodem
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macckone
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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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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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aga
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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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dotemily
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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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szuko03
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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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